CA2127946A1 - High power, high gain, low noise, two-stage optical amplifiers - Google Patents
High power, high gain, low noise, two-stage optical amplifiersInfo
- Publication number
- CA2127946A1 CA2127946A1 CA002127946A CA2127946A CA2127946A1 CA 2127946 A1 CA2127946 A1 CA 2127946A1 CA 002127946 A CA002127946 A CA 002127946A CA 2127946 A CA2127946 A CA 2127946A CA 2127946 A1 CA2127946 A1 CA 2127946A1
- Authority
- CA
- Canada
- Prior art keywords
- amplifying
- stage
- optical signal
- pump light
- signal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/29—Repeaters
- H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
- H01S3/06—Construction or shape of active medium
- H01S3/063—Waveguide lasers, i.e. whereby the dimensions of the waveguide are of the order of the light wavelength
- H01S3/067—Fibre lasers
- H01S3/06754—Fibre amplifiers
- H01S3/06758—Tandem amplifiers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/29—Repeaters
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S2301/00—Functional characteristics
- H01S2301/02—ASE (amplified spontaneous emission), noise; Reduction thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/005—Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping
- H01S3/0078—Frequency filtering
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/094061—Shared pump, i.e. pump light of a single pump source is used to pump plural gain media in parallel
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
- H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
- H01S3/09408—Pump redundancy
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B2210/00—Indexing scheme relating to optical transmission systems
- H04B2210/003—Devices including multiple stages, e.g., multi-stage optical amplifiers or dispersion compensators
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
- Glass Compositions (AREA)
Abstract
Abstract of the Disclosure High output power, high gain, and low noise are achieved in a two-stage optical amplifier, suitable for use as a repeater for a long haul lightwave communication system, in accordance with the principles of the invention, by employing a first amplifying stage having a signal gain sufficiently small to prevent self-saturation by amplified stimulated emission (ASE) that uses counter-propagating pump light to cause maximum inversion of the first stage amplifying medium. In an illustrative embodiment of the invention, EDFAs are used in each of two amplifying stages. The length of the EDFA in the first stage is short enough to ensure nearly complete inversion of the EDFA from pump light that counter-propagates with the signal. The counter-propagating pump light allows the invention to advantageously avoid the significant noise figure penalty from the input loss associated with co-propagating pump light. And, noise figure is improved becausecomplete inversion is achieved throughout the EDFA, and, at the input where the noise figure is most sensitive to inversion. The short length also eliminates self-saturation of the EDFA from ASE which degrades the noise figure. However, the length, and hence the gain, of the EDFA in the first stage is long enough to provide sufficient gain so that the noise figure of the two-stage amplifier, as a whole, is determined primarily by that of the first stage. A second EDFA in the second stage of the amplifier may then be configured using co-propagating or counter-propagating pump light for additional signal amplification to provide the required output power and gain for long haul lightwave systems. Other aspects of illustrative embodiments of the invention include the use of passive optical elements including filters, isolators, and attenuators. (FIG. 1)
Description
~ :
` h ~ J~
,-~ .
HIGH POWER, HIGH GAIN, LOW NOISE, TWO-STAGE OPTICAL
AMPl,lFIER ~;
Technircal Field This invention relates generally to optical amplifiers for lightwave communications 5 and, more particularly to a two-stage optical amplifier having high output power, high gain, and low noise.
,, Background of the Invention ~ ~ -Optical amplifiers in the form of erbium-doped fiber amplifiers (EDFAs) are expected to replace the current optoelectronic regenerators in many future opti~al long --l 0 haul terrestrial and undersea lightwave communications systems. Optical amplifiers may be used as power amplifiers to boost transmitter power; as preamplifiers to increase receiver sensitivity; and, as repeaters to periodically boost the signal to a level sufficient for it to traverse the entire lightwave system.
Optical amplifiers are designed by considering a number of parameters including gain, output power, compression (i.e. gain saturation), and noise performance. Noise performance is typically measured by the noise figure which is defined as the signal-to-noise ratio at the input of the optical amplifier divided by that at the output. When optical amplifiers are used as repeaters, they should operate with very low noise figure and high output power in order to maximize the distance between adjacent repeaters in thelightwave system. For example, it would be very desirable, in future lightwave communications systems, to increase the distance between adjacent repeaters from the current 40 km to 100 km, or more. High output power is also required where repeaters are used in systems employing multiple multiplexed channels. In addition, repeaters must have sufficient gain to compensate for the loss in the optical fiber span between repeaters.
One prior art optical amplifier arrangement uses multip!e EDFA stages to improvethe gain characteristics of the optical amplifier. In this arrangement, two separate stages of amplification are separated by passive optical components. These passive opticalcomponents are required elements in most repeater arrangements, and may include isolators, filters, pump multiplexers, and the like. Typically in the prior art, passive optical elements are positioned at either the input or output of the optical amplifier. In this particular prior art arrangement, however, the placement of the passive elements between the two stages allows the multistage amplifier to have high gain while avoiding an increase in noise that would occur if the passive element were placed at the input of a single stage ::
. ::
;~3 amplifier, or a loss of output power that would result if the elements were placed at the output of a single stage amplifier. Although the prior art multistage optical amplifier operates satisfactorily in certain applications, it has some limitations for use as a repeater in future long haul lightwave communications systems.
5 Summarv of the Invention High output power, high gain, and low noise are achieved in a two-stage optical amplifier, suitable for use as a repeater for a long haul lightwave communication system, in accordance with the principles of the invention, by employing a first amplifying stage having a signal gain sufficiently small to prevent self-saturation by amplified stimulated 10 emission (ASE) that uses counter-propagating pump light to cause maximum inversion of the first stage amplifying medium.
In an illustrative embodiment of the invention, EDFAs are used in each of two amplifying stages. The length of the EDFA in the first stage is short enough to ensure nearly complete inversion of the EDFA from pump light that counter-propagates with the 15 signal. The counter-propagating pump light allows the invention to advantageously avoid the significant noise figure penalty from the input loss associated with co-propagating pump light. Noise figure is improved because complete inversion is achieved throughout the the first stage EDFA, and in particular, at the input where the noise figure is most sensitive to inversion. The short length also eliminates self-saturation of the EDFA from 20 ASE which degrades the noise figure. However, the length of the EDFA in the first stage is long enough to provide sufficient gain so that the noise figure of the two-stage amplifier, as a whole, is determined primarily by that of the first stage. A second EDFAin the second stage of the amplifier may then be configured using co-propagating or counter-propagating pump light for additional signal amplification to provide the required output 25 power and gain for long haul lightwave systems. Other aspects of illustrative embodiments of the invention include the use of passive optical elements including filters, isolators, and attenuators.
~ :r- ~ s .,~
.
` h ~ J~
,-~ .
HIGH POWER, HIGH GAIN, LOW NOISE, TWO-STAGE OPTICAL
AMPl,lFIER ~;
Technircal Field This invention relates generally to optical amplifiers for lightwave communications 5 and, more particularly to a two-stage optical amplifier having high output power, high gain, and low noise.
,, Background of the Invention ~ ~ -Optical amplifiers in the form of erbium-doped fiber amplifiers (EDFAs) are expected to replace the current optoelectronic regenerators in many future opti~al long --l 0 haul terrestrial and undersea lightwave communications systems. Optical amplifiers may be used as power amplifiers to boost transmitter power; as preamplifiers to increase receiver sensitivity; and, as repeaters to periodically boost the signal to a level sufficient for it to traverse the entire lightwave system.
Optical amplifiers are designed by considering a number of parameters including gain, output power, compression (i.e. gain saturation), and noise performance. Noise performance is typically measured by the noise figure which is defined as the signal-to-noise ratio at the input of the optical amplifier divided by that at the output. When optical amplifiers are used as repeaters, they should operate with very low noise figure and high output power in order to maximize the distance between adjacent repeaters in thelightwave system. For example, it would be very desirable, in future lightwave communications systems, to increase the distance between adjacent repeaters from the current 40 km to 100 km, or more. High output power is also required where repeaters are used in systems employing multiple multiplexed channels. In addition, repeaters must have sufficient gain to compensate for the loss in the optical fiber span between repeaters.
One prior art optical amplifier arrangement uses multip!e EDFA stages to improvethe gain characteristics of the optical amplifier. In this arrangement, two separate stages of amplification are separated by passive optical components. These passive opticalcomponents are required elements in most repeater arrangements, and may include isolators, filters, pump multiplexers, and the like. Typically in the prior art, passive optical elements are positioned at either the input or output of the optical amplifier. In this particular prior art arrangement, however, the placement of the passive elements between the two stages allows the multistage amplifier to have high gain while avoiding an increase in noise that would occur if the passive element were placed at the input of a single stage ::
. ::
;~3 amplifier, or a loss of output power that would result if the elements were placed at the output of a single stage amplifier. Although the prior art multistage optical amplifier operates satisfactorily in certain applications, it has some limitations for use as a repeater in future long haul lightwave communications systems.
5 Summarv of the Invention High output power, high gain, and low noise are achieved in a two-stage optical amplifier, suitable for use as a repeater for a long haul lightwave communication system, in accordance with the principles of the invention, by employing a first amplifying stage having a signal gain sufficiently small to prevent self-saturation by amplified stimulated 10 emission (ASE) that uses counter-propagating pump light to cause maximum inversion of the first stage amplifying medium.
In an illustrative embodiment of the invention, EDFAs are used in each of two amplifying stages. The length of the EDFA in the first stage is short enough to ensure nearly complete inversion of the EDFA from pump light that counter-propagates with the 15 signal. The counter-propagating pump light allows the invention to advantageously avoid the significant noise figure penalty from the input loss associated with co-propagating pump light. Noise figure is improved because complete inversion is achieved throughout the the first stage EDFA, and in particular, at the input where the noise figure is most sensitive to inversion. The short length also eliminates self-saturation of the EDFA from 20 ASE which degrades the noise figure. However, the length of the EDFA in the first stage is long enough to provide sufficient gain so that the noise figure of the two-stage amplifier, as a whole, is determined primarily by that of the first stage. A second EDFAin the second stage of the amplifier may then be configured using co-propagating or counter-propagating pump light for additional signal amplification to provide the required output 25 power and gain for long haul lightwave systems. Other aspects of illustrative embodiments of the invention include the use of passive optical elements including filters, isolators, and attenuators.
~ :r- ~ s .,~
.
2 ~ I iù
Brief Description of the Drawing In the drawing:
FIG. 1 shows a simplified block diagram of an illustrative arrangement of elements forming a two-stage optical amplifier embodying the principles of the invention;S FIG. 2 shows a second arrangement of elements, in accordance with the princip]es of the invention, including the illustrative embodiment of FIG. I in combination with a post second stage attenuation element; -FIG. 3 shows a third arrangement of elements in accordance with the principles of the invention; and FIG. 4 shows a fourth arrangement of elements in accordance with the principles of the invention.
Detailed Description FIG. 1 shows a simplified block diagram of an illustrative arrangement of elements forming a two-stage optical amplifier embodying the principles of the invention. The optical amplifier has two stages comprising erbium-doped fibers l 0 and 20. In first stage 40, wavelength division multiplexer (WDM) 30 permits the introduction of light from a pump source to counter-propagate with respect to a signal which is presented at the input of first stage 40. Optical isolator 15 is positioned between the input of first stage 40 and erbium-doped fiber l0 to suppress reflections and pump light source oscillations. Erbium-doped fibers, WDMs, and optical isolators and the functions employed therein are well known in the art.
Pump light is generated by laser diode 80 at one of any number of wavelengths, for example, 980 nm or l 480 nm. It may be desirable in some applications of the invention to use a separate laser diode 90 to generate pump light used in second stage 50 of the optical amplifier. Alternatively, a single laser diode may be coupled into splitter 70 ~o distribute pump light between first stage 40 and second stage 50 of the optical amplifier. Or, laser diodes 80 and 90 could be coupled into splitter 70 for enhanced reliability as pump light would still be introduced into both stages even if one laser diode failed. Splitter 70 could be, in some applications of the invention, a 3 dB splitter. Laser diodes and splitters and the functions employed therein are well known in the art. It may be desirable, in some applications of the invention, to use a splitting ratio other than 50% in splitter 70.
In accordance with an aspect of the invention, the use of counter-propagating pump light in first stage 40 advantageously results in a very low noise figure for the two-: ' ' ` , . ' ' ' ' ' . : ~ , .', ! "~ ~ . ' ' ; , ' ' ", , , , ' `': ' ' , . .' . ' ' 4 2 ~
,.
stage optical amplifier as a whole, where noise figure is defined as the signal-to-noise ratio at the input of the optical amplifier divided by that at the output. The very low noise figure is realized, in part~ because the use of counter-propagating pump light avoids the loss from the WDM at the input of erbium-doped fiber 10 that would result if co-propagating pump S light was used in first stage 40. A very low noise figure is further realized by selecting the length of erbium-doped fiber 10 to be sufficiently short so that erbium-doped fiber 10 achieves substantially total inversion from strongly pumped counter-propagating pump light, and erbium-doped fiber 10 experiences little self-saturation by amplified stimulated emission (ASE). The short length assures that erbium-doped fiber 10 has substantially total inversion at its input which is of special importance since the noise figure is most sensitive to the degree of inversion at the input. However, the length of erbium-doped fiber 10 is selected to be long enough to provide sufficient gain through first stage 40 so that the noise figure of the two-stage amplifier, as a whole, is determined primarily by that of first stage 40. For purposes of this example, and not as a limitation on the invention, small signal gains under strong pumping of between approximately 10 and 25 dB in the range of wavelengths between 1540 and 1565 nm have been shown to be effective toensure that pump light at the input to erbium-doped fiber 10 will be sufficient to maintain a high degree of inversion. The fact that a ve~ low noise figure is achieved with counter-propagating pump light, in accordance with an aspect of the invention, is unexpected and surprising, given that the teachings of the prior art is that co-propagating pump light is used to achieve the good inversion at the input of the erbium-doped ~Iber necessary for a low noise figure.
First stage 40 and second stage 50 are coupled with coupling fiber 45 so that the amplified signal output from first stage 40 is presented to the input of second stage 50.
Isolator 35 and filter 55 are positioned in fiber 45 to ensure that backward-propagating ASE from second stage 50 does not reach first stage 40 which would result in a decrease in inversion at the input to first stage 40 where the backward-propagating ASE power would be the highest, and the noise figure most sensitive to inversion. Filter 55 is tuned to remove wavelength components outside the signal band propagating in both directions along coupling fiber 45, which advantageously minimizes self-saturation by ASE in second stage 50. However, it may be desirable in some applications, for filter 55 to be specifically tuned to remove the wavelength component of ASE at 1530 nm and neighboring wavelengths. ASE at 1530 nm and neighboring wavelengths contain the greatest spectral density, often by 10 to 15 dB or more over other wavelengths, and would have thegreatest inversion degrading effect because of its strong emission cross section were it not removed by filter 55.
~ ~,.~- . - - - - ... . . .. . ..
:,:.: .. " .; . .. ~ - , .; -.
. $~
. .,.. :~ ..; :~. : : ., :,:~ . ~ . .. . .
~ ':~` `'. ,,. -,. ::`' ' :,~: :
.~ :,~. ,: . . , ~ .,. , ~ ~: . : ~
.--Second stage 50 is comprised of WDM 60 to couple pump light into erbium-doped fiber 20, and isolator 25 which suppresses oscillations and noise figure penalties associated with reflections. WDM 60 is positioned to couple pump light into erbium-doped fiber 20 which co-propagates with the signal to advantageously allow additional signal gain without additional degradation in noise figure. The length of erbium-doped fiber 20 may be configured so that with strong pumping, substantial gain and output power may be realized. Two-stage amplifiers, built in accordance with the principles of the invention, have demonstrated gain greater than 25 dB, output power greater than 10 dBm, and noise figure below 3.4 dB with 6 dB gain compression and 980 nm pump light from 45 mW
lasers.
FIG. 2 shows a second arrangement of elements, in accordance with the principlesof the invention, including the illustrative embodiment of FIG. I in combination with a post second stage attenuation (i.e. Ioss) element. The addition of loss element 295 advantageously allows the two-stage amplifier to be employed in applications requiring low to moderate output powers such as soliton long haul submarine transmission systems.
The addition of loss element 295 allows excess signal power resulting from the high pump power needed for low noise figure to be attenuated in order to avoid penalties associated with nonlinear optical processes in the transmission fiber. However, the gain of the two-stage amplifier must be increased by the amount of the post second stage loss. In the prior art, such gain increase would typically introduce noise due to self-satura~ion. ln accordance with an aspect of the invention, however, maximum benefit may be realized by post second stage !oss since self-saturation in first stage 40 is avoided and minimized in second stage 50. At the same time, input losses which directly increase the noise figure are avoided by the counter-propagating pump arrangement in first stage 40.
FIG. 3 shows a third illustrative arrangement of elements in accordance with theprinciples of the invention. This arrangement is similar to that shown in FIG. 2, with the exception that the isolator at the input of first stage 40 (FIG. 2) is eliminated. This advantageously lowers input losses even further for an additional benefit to noise figure. In this illustrative arrangement, erbium-doped fiber 10 must be even shorter than those employed in the other illustrative arrangements discussed above, to avoid noise figure penalties and multipath interference associated with any reflections arising upstream of the two-stage ampli~ler. For example, in long haul systems where the upstream transmission f~lber will give rise to Rayleigh scattering induced reflections at a level of about -30 dB, the gain of first stage 40 must be set sufficiendy low that multipath interference will not be at a high enough level to degrade performance.
: . . ~ . .; , . . : ., - ~ . "
~, !, ~.. ;,. . , ' ~ ~ ~
6 21 ~ 7 3 ~1 G
FlG. 4 shows a fourth arrangement of elements in accordance with the principles of the invention. This arrangement is similar to that shown in FIG. 2 except that a single pump signal from laser diode 405 enters at WDM 465 which counter-propagates through second stage 50. The residual pump power of second stage S0 is then coupled through S WDMs 60 and 30 and WDM coupling fiber 490 to first stage 40. Thus, the use of multiple pump light sources and splitters is avoided. Such an arrangement wouid be suitable for use in applications where high power is not required so that the pump light, even after passing through second stage S0, will still have enough power to ensure a high degree of inversion at the input of first stage 40.
The above-described invention provides a method and apparatus for achieving a high power, high gain, low noise two-stage optical amplifier. It will be understood that the particular methods described are only illustrative of the principles of the present invention, and that various modifications could be made by those skilled in the art without departing from the spirit and scope of the present invention, which is limited only by the claims that IS follow.
,~,~ i~,`' ~; ~ . '! ' ,'',` '~
Brief Description of the Drawing In the drawing:
FIG. 1 shows a simplified block diagram of an illustrative arrangement of elements forming a two-stage optical amplifier embodying the principles of the invention;S FIG. 2 shows a second arrangement of elements, in accordance with the princip]es of the invention, including the illustrative embodiment of FIG. I in combination with a post second stage attenuation element; -FIG. 3 shows a third arrangement of elements in accordance with the principles of the invention; and FIG. 4 shows a fourth arrangement of elements in accordance with the principles of the invention.
Detailed Description FIG. 1 shows a simplified block diagram of an illustrative arrangement of elements forming a two-stage optical amplifier embodying the principles of the invention. The optical amplifier has two stages comprising erbium-doped fibers l 0 and 20. In first stage 40, wavelength division multiplexer (WDM) 30 permits the introduction of light from a pump source to counter-propagate with respect to a signal which is presented at the input of first stage 40. Optical isolator 15 is positioned between the input of first stage 40 and erbium-doped fiber l0 to suppress reflections and pump light source oscillations. Erbium-doped fibers, WDMs, and optical isolators and the functions employed therein are well known in the art.
Pump light is generated by laser diode 80 at one of any number of wavelengths, for example, 980 nm or l 480 nm. It may be desirable in some applications of the invention to use a separate laser diode 90 to generate pump light used in second stage 50 of the optical amplifier. Alternatively, a single laser diode may be coupled into splitter 70 ~o distribute pump light between first stage 40 and second stage 50 of the optical amplifier. Or, laser diodes 80 and 90 could be coupled into splitter 70 for enhanced reliability as pump light would still be introduced into both stages even if one laser diode failed. Splitter 70 could be, in some applications of the invention, a 3 dB splitter. Laser diodes and splitters and the functions employed therein are well known in the art. It may be desirable, in some applications of the invention, to use a splitting ratio other than 50% in splitter 70.
In accordance with an aspect of the invention, the use of counter-propagating pump light in first stage 40 advantageously results in a very low noise figure for the two-: ' ' ` , . ' ' ' ' ' . : ~ , .', ! "~ ~ . ' ' ; , ' ' ", , , , ' `': ' ' , . .' . ' ' 4 2 ~
,.
stage optical amplifier as a whole, where noise figure is defined as the signal-to-noise ratio at the input of the optical amplifier divided by that at the output. The very low noise figure is realized, in part~ because the use of counter-propagating pump light avoids the loss from the WDM at the input of erbium-doped fiber 10 that would result if co-propagating pump S light was used in first stage 40. A very low noise figure is further realized by selecting the length of erbium-doped fiber 10 to be sufficiently short so that erbium-doped fiber 10 achieves substantially total inversion from strongly pumped counter-propagating pump light, and erbium-doped fiber 10 experiences little self-saturation by amplified stimulated emission (ASE). The short length assures that erbium-doped fiber 10 has substantially total inversion at its input which is of special importance since the noise figure is most sensitive to the degree of inversion at the input. However, the length of erbium-doped fiber 10 is selected to be long enough to provide sufficient gain through first stage 40 so that the noise figure of the two-stage amplifier, as a whole, is determined primarily by that of first stage 40. For purposes of this example, and not as a limitation on the invention, small signal gains under strong pumping of between approximately 10 and 25 dB in the range of wavelengths between 1540 and 1565 nm have been shown to be effective toensure that pump light at the input to erbium-doped fiber 10 will be sufficient to maintain a high degree of inversion. The fact that a ve~ low noise figure is achieved with counter-propagating pump light, in accordance with an aspect of the invention, is unexpected and surprising, given that the teachings of the prior art is that co-propagating pump light is used to achieve the good inversion at the input of the erbium-doped ~Iber necessary for a low noise figure.
First stage 40 and second stage 50 are coupled with coupling fiber 45 so that the amplified signal output from first stage 40 is presented to the input of second stage 50.
Isolator 35 and filter 55 are positioned in fiber 45 to ensure that backward-propagating ASE from second stage 50 does not reach first stage 40 which would result in a decrease in inversion at the input to first stage 40 where the backward-propagating ASE power would be the highest, and the noise figure most sensitive to inversion. Filter 55 is tuned to remove wavelength components outside the signal band propagating in both directions along coupling fiber 45, which advantageously minimizes self-saturation by ASE in second stage 50. However, it may be desirable in some applications, for filter 55 to be specifically tuned to remove the wavelength component of ASE at 1530 nm and neighboring wavelengths. ASE at 1530 nm and neighboring wavelengths contain the greatest spectral density, often by 10 to 15 dB or more over other wavelengths, and would have thegreatest inversion degrading effect because of its strong emission cross section were it not removed by filter 55.
~ ~,.~- . - - - - ... . . .. . ..
:,:.: .. " .; . .. ~ - , .; -.
. $~
. .,.. :~ ..; :~. : : ., :,:~ . ~ . .. . .
~ ':~` `'. ,,. -,. ::`' ' :,~: :
.~ :,~. ,: . . , ~ .,. , ~ ~: . : ~
.--Second stage 50 is comprised of WDM 60 to couple pump light into erbium-doped fiber 20, and isolator 25 which suppresses oscillations and noise figure penalties associated with reflections. WDM 60 is positioned to couple pump light into erbium-doped fiber 20 which co-propagates with the signal to advantageously allow additional signal gain without additional degradation in noise figure. The length of erbium-doped fiber 20 may be configured so that with strong pumping, substantial gain and output power may be realized. Two-stage amplifiers, built in accordance with the principles of the invention, have demonstrated gain greater than 25 dB, output power greater than 10 dBm, and noise figure below 3.4 dB with 6 dB gain compression and 980 nm pump light from 45 mW
lasers.
FIG. 2 shows a second arrangement of elements, in accordance with the principlesof the invention, including the illustrative embodiment of FIG. I in combination with a post second stage attenuation (i.e. Ioss) element. The addition of loss element 295 advantageously allows the two-stage amplifier to be employed in applications requiring low to moderate output powers such as soliton long haul submarine transmission systems.
The addition of loss element 295 allows excess signal power resulting from the high pump power needed for low noise figure to be attenuated in order to avoid penalties associated with nonlinear optical processes in the transmission fiber. However, the gain of the two-stage amplifier must be increased by the amount of the post second stage loss. In the prior art, such gain increase would typically introduce noise due to self-satura~ion. ln accordance with an aspect of the invention, however, maximum benefit may be realized by post second stage !oss since self-saturation in first stage 40 is avoided and minimized in second stage 50. At the same time, input losses which directly increase the noise figure are avoided by the counter-propagating pump arrangement in first stage 40.
FIG. 3 shows a third illustrative arrangement of elements in accordance with theprinciples of the invention. This arrangement is similar to that shown in FIG. 2, with the exception that the isolator at the input of first stage 40 (FIG. 2) is eliminated. This advantageously lowers input losses even further for an additional benefit to noise figure. In this illustrative arrangement, erbium-doped fiber 10 must be even shorter than those employed in the other illustrative arrangements discussed above, to avoid noise figure penalties and multipath interference associated with any reflections arising upstream of the two-stage ampli~ler. For example, in long haul systems where the upstream transmission f~lber will give rise to Rayleigh scattering induced reflections at a level of about -30 dB, the gain of first stage 40 must be set sufficiendy low that multipath interference will not be at a high enough level to degrade performance.
: . . ~ . .; , . . : ., - ~ . "
~, !, ~.. ;,. . , ' ~ ~ ~
6 21 ~ 7 3 ~1 G
FlG. 4 shows a fourth arrangement of elements in accordance with the principles of the invention. This arrangement is similar to that shown in FIG. 2 except that a single pump signal from laser diode 405 enters at WDM 465 which counter-propagates through second stage 50. The residual pump power of second stage S0 is then coupled through S WDMs 60 and 30 and WDM coupling fiber 490 to first stage 40. Thus, the use of multiple pump light sources and splitters is avoided. Such an arrangement wouid be suitable for use in applications where high power is not required so that the pump light, even after passing through second stage S0, will still have enough power to ensure a high degree of inversion at the input of first stage 40.
The above-described invention provides a method and apparatus for achieving a high power, high gain, low noise two-stage optical amplifier. It will be understood that the particular methods described are only illustrative of the principles of the present invention, and that various modifications could be made by those skilled in the art without departing from the spirit and scope of the present invention, which is limited only by the claims that IS follow.
,~,~ i~,`' ~; ~ . '! ' ,'',` '~
Claims (24)
1. Apparatus for amplifying an optical signal comprising:
first amplifying means having an input and an output for amplifying said optical signal, said first amplifying means having a first predetermined signal gain so that there is no substantial self-saturation by amplified spontaneous emission;
pumping means coupled to said first amplifying means for pumping said first amplifying means with counter-propagating pump light to cause said first amplifying means to achieve substantially total population inversion;
second amplifying means having an input and an output and having a second predetermined signal gain for further amplifying said optical signal to apredetermined output signal power; and coupling means for coupling said output of said first amplifying means to said input of said second amplifying means.
first amplifying means having an input and an output for amplifying said optical signal, said first amplifying means having a first predetermined signal gain so that there is no substantial self-saturation by amplified spontaneous emission;
pumping means coupled to said first amplifying means for pumping said first amplifying means with counter-propagating pump light to cause said first amplifying means to achieve substantially total population inversion;
second amplifying means having an input and an output and having a second predetermined signal gain for further amplifying said optical signal to apredetermined output signal power; and coupling means for coupling said output of said first amplifying means to said input of said second amplifying means.
2. The apparatus of claim 1 wherein said first amplifying means comprises an erbium-doped fiber amplifier.
3. The apparatus of claim 1 wherein said second amplifying means comprises an erbium-doped fiber amplifier.
4. The apparatus of claim 2 wherein said predetermined signal gain is substantially equal to a value between 10 and 25 decibels in a range of wavelengths between 1540 and 1565 nanometers.
5. The apparatus of claim 1 further including second pumping means coupled for pumping said second amplifying means with counter-propagating pump light.
6. The apparatus of claim 1 wherein said second amplifying means are coupled to second pumping means for pumping said second amplifying means with co-propagating pump light.
7. The apparatus of claim 4 wherein said coupling means includes isolator means for isolating amplified spontaneous emission in said second amplifying means from said first amplifying means.
8. The apparatus of claim 7 wherein said coupling means includes filtering means for filtering said amplified optical signal to remove wavelength components outside the signal band from said amplified optical signal.
9. The apparatus of claim 7 wherein said coupling means includes filtering means for filtering said amplified optical signal to remove wavelength components substantially equal to 1530 nanometers from said amplified optical signal.
10. The apparatus of claim 9 wherein said second amplifying means includes means for attenuating said further amplified optical signal by a predetermined amount.
11. The apparatus of claim 8 wherein said second amplifying means includes isolator means for isolating said output of said second amplifying means from reflections.
12. The apparatus of claim 11 wherein said first amplifying means includes isolator means for isolating said input of said first amplifying means from reflections.
13. A method for use in amplifying an optical signal comprising the steps of:
amplifying said optical signal in a first amplifying stage having an input and an output at a first predetermined signal gain so that there is no substantial self-saturation by amplified spontaneous emission;
pumping said first amplifying stage with counter-propagating light so that said first stage achieves substantially total population inversion.
further amplifying said optical signal in a second amplifying stage having an input and an output at a second predetermined signal gain to a predetermined output signal level; and coupling said output of said first optical amplifying stage to said input of said second optical amplifying stage.
amplifying said optical signal in a first amplifying stage having an input and an output at a first predetermined signal gain so that there is no substantial self-saturation by amplified spontaneous emission;
pumping said first amplifying stage with counter-propagating light so that said first stage achieves substantially total population inversion.
further amplifying said optical signal in a second amplifying stage having an input and an output at a second predetermined signal gain to a predetermined output signal level; and coupling said output of said first optical amplifying stage to said input of said second optical amplifying stage.
14. The method of claim 13 wherein said first amplifying stage is comprised of an erbium-doped fiber amplifier.
15. The method of claim 13 wherein said second amplifying stage is comprised of an erbium-doped fiber amplifier.
16. The method of claim 15 wherein said step of amplifying includes amplifying at a signal gain substantially equal to a value between 10 and 25 decibels in a range of wavelengths between 1540 and 1565 nanometers.
17. The method of claim 13 wherein said step of further amplifying includes pumping said second amplifying stage with counter-propagating pump light.
18. The method of claim 13 wherein said step of further amplifying includes pumping said second amplifying stage with co-propagating pump light.
19. The method of claim 18 wherein said step of coupling includes isolating said amplified spontaneous emission in said second amplifying stage from said first amplifying stage.
20. The method of claim 19 wherein said step of coupling includes filtering said amplified optical signal to remove wavelength components outside the signal band from said amplified signal.
21. The method of claim 19 wherein said step of coupling includes filtering said amplified optical signal to remove wavelength components substantially equal to 1530 nanometers from said amplified optical signal.
22. The method of claim 21 wherein said step of further amplifying includes attenuating said further amplified optical signal by a predetermined amount.
23. The apparatus of claim 20 wherein said step of further amplifying includes isolating said output of said second amplifying stage from reflections.
24. The method of claim 23 wherein said step of amplifying includes isolating said input of said first amplifying stage from reflections.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/129,825 US5430572A (en) | 1993-09-30 | 1993-09-30 | High power, high gain, low noise, two-stage optical amplifier |
US129,825 | 1993-09-30 |
Publications (1)
Publication Number | Publication Date |
---|---|
CA2127946A1 true CA2127946A1 (en) | 1995-03-31 |
Family
ID=22441771
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002127946A Abandoned CA2127946A1 (en) | 1993-09-30 | 1994-07-12 | High power, high gain, low noise, two-stage optical amplifiers |
Country Status (6)
Country | Link |
---|---|
US (1) | US5430572A (en) |
EP (1) | EP0647000A1 (en) |
JP (1) | JPH07176817A (en) |
KR (1) | KR950010416A (en) |
AU (1) | AU679098B2 (en) |
CA (1) | CA2127946A1 (en) |
Families Citing this family (102)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5721635A (en) * | 1993-11-24 | 1998-02-24 | Sumitomo Electric Industries, Ltd. | Optical fiber amplifier and optical amplifier repeater |
DE69416396T2 (en) * | 1994-04-11 | 1999-06-10 | Hewlett Packard Gmbh | Noise level measurement method in the presence of a signal |
JP3195160B2 (en) | 1994-05-06 | 2001-08-06 | 株式会社日立製作所 | Optical amplifier |
JPH08248455A (en) * | 1995-03-09 | 1996-09-27 | Fujitsu Ltd | Optical amplifier for wavelength multiplexing |
JP3618008B2 (en) * | 1995-03-17 | 2005-02-09 | 富士通株式会社 | Optical amplifier |
DE69637562D1 (en) * | 1995-03-20 | 2008-07-24 | Fujitsu Ltd | Method and device for optical signal processing |
US6195480B1 (en) | 1997-08-06 | 2001-02-27 | Hitachi, Ltd. | Optical transmission device and optical transmission system employing the same |
US6321002B1 (en) | 1995-05-01 | 2001-11-20 | Hitachi, Ltd. | Optical amplifier, optical transmission equipment, optical transmission system, and method thereof |
US6229936B1 (en) * | 1995-05-01 | 2001-05-08 | Hitachi, Ltd. | Optical amplifier, optical transmission equipment, optical transmission system, and method thereof |
JP2846291B2 (en) * | 1995-08-24 | 1999-01-13 | 松下電器産業株式会社 | Intermediate isolator type optical fiber amplifier and optical fiber transmission system |
FR2739981B1 (en) * | 1995-10-13 | 1998-01-02 | Photonetics | OPTICAL SIGNAL AMPLIFIER AND CORRESPONDING AMPLIFICATION METHOD |
JP3422398B2 (en) * | 1995-12-07 | 2003-06-30 | 富士通株式会社 | Center-of-gravity wavelength monitoring method and apparatus, optical amplifier, and optical communication system |
JP2928149B2 (en) * | 1995-12-14 | 1999-08-03 | 日本電気株式会社 | Optical fiber amplifier |
US5710659A (en) * | 1995-12-19 | 1998-01-20 | Lucent Technologies Inc. | Low tilt, high gain fiber amplifier |
KR100194421B1 (en) * | 1996-01-29 | 1999-06-15 | 윤종용 | Fiber optic amplifier |
KR970064034A (en) * | 1996-02-10 | 1997-09-12 | 김광호 | Optical transmission systems and lasers for multi-wavelength automatic power and gain control |
US5673280A (en) * | 1996-02-12 | 1997-09-30 | Lucent Technologies Inc. | Article comprising low noise optical fiber raman amplifier |
US5815308A (en) * | 1996-05-20 | 1998-09-29 | Northern Telecom Limited | Bidirectional optical amplifier |
US6369938B1 (en) | 1996-05-28 | 2002-04-09 | Fujitsu Limited | Multi-wavelength light amplifier |
JP3402069B2 (en) * | 1996-06-12 | 2003-04-28 | Kddi株式会社 | Optical amplification transmission system |
CA2205705A1 (en) * | 1996-06-26 | 1997-12-26 | Franklin W. Kerfoot, Iii | Arrangement for reducing insertion loss impairment of optical amplifiers |
JPH1012954A (en) * | 1996-06-26 | 1998-01-16 | Fujitsu Ltd | Optical amplifier |
US6016213A (en) * | 1996-07-08 | 2000-01-18 | Ditech Corporation | Method and apparatus for optical amplifier gain and noise figure measurement |
US5761234A (en) | 1996-07-09 | 1998-06-02 | Sdl, Inc. | High power, reliable optical fiber pumping system with high redundancy for use in lightwave communication systems |
KR980013060A (en) * | 1996-07-15 | 1998-04-30 | 김광호 | An optical fiber amplifying device for amplifying transmission light by bi-directionally exciting pump power |
US6084704A (en) * | 1996-11-06 | 2000-07-04 | Corning Incorporated | Crosstalk suppression in a multipath optical amplifier |
JPH10209540A (en) * | 1997-01-23 | 1998-08-07 | Nec Corp | Optical fiber amplifier |
EP1914849B1 (en) * | 1997-02-18 | 2011-06-29 | Nippon Telegraph & Telephone Corporation | Optical amplifier and a transmission system using the same |
EP0968579B1 (en) * | 1997-03-17 | 2003-06-04 | JDS Uniphase Corporation | Multiple stage optical fiber amplifier |
WO1998052305A1 (en) * | 1997-05-16 | 1998-11-19 | Scientific-Atlanta, Inc. | Redundant optical power supply for remote pumping of fiber optic gain modules |
KR100326039B1 (en) * | 1997-06-30 | 2002-09-05 | 삼성전자 주식회사 | Fiber amplifier having absorber |
NZ330998A (en) * | 1997-08-23 | 2000-01-28 | Pirelli Cavi E Sistemi Spa | Optical fibre amplifier with twin couplers for multimode pump laser, multimode scrambler between couplers |
GB9801184D0 (en) * | 1998-01-20 | 1998-03-18 | Alsthom Cge Alcatel | An optical repeater |
CA2320872A1 (en) | 1998-02-20 | 1999-08-26 | Paul N. Freeman | Upgradable, gain flattened fiber amplifiers for wdm applications |
US6603596B2 (en) * | 1998-03-19 | 2003-08-05 | Fujitsu Limited | Gain and signal level adjustments of cascaded optical amplifiers |
JPH11275021A (en) * | 1998-03-20 | 1999-10-08 | Fujitsu Ltd | Optical amplifier |
GB2337357A (en) * | 1998-05-13 | 1999-11-17 | Alsthom Cge Alcatel | Optical amplifier |
JP3102410B2 (en) | 1998-05-18 | 2000-10-23 | 日本電気株式会社 | Light switch |
IT1313112B1 (en) * | 1998-08-25 | 2002-06-17 | Samsung Electronics Co Ltd | LONG BAND OPTICAL FIBER AMPLIFIER WITH REINFORCED POWER CONVERSION EFFICIENCY |
CA2244160A1 (en) | 1998-08-26 | 2000-02-26 | Hamid Hatami-Hanza | High gain, high power, low noise optical waveguide amplifiers |
US6545799B1 (en) | 1998-09-02 | 2003-04-08 | Corning Incorporated | Method and apparatus for optical system link control |
US6362916B2 (en) | 1998-09-25 | 2002-03-26 | Fiver Laboratories | All fiber gain flattening optical filter |
US6141142A (en) * | 1999-02-19 | 2000-10-31 | Lucent Technologies Inc. | Article comprising an L-Band optical fiber amplifier |
US6297903B1 (en) * | 1999-11-16 | 2001-10-02 | Sdl, Inc. | Multiple stage optical fiber amplifier and signal generator |
JP2001223641A (en) * | 2000-02-14 | 2001-08-17 | Sumitomo Electric Ind Ltd | Optical transmission system and optical transmission method |
JP2001230477A (en) * | 2000-02-16 | 2001-08-24 | Nec Corp | Light amplifier |
DE60138935D1 (en) * | 2000-02-23 | 2009-07-23 | Fujitsu Ltd | Optical amplifier |
US6381063B1 (en) * | 2000-03-16 | 2002-04-30 | Corning Incorporated | Long band optical amplifier |
KR20010097980A (en) * | 2000-04-27 | 2001-11-08 | 이진섭 | Constant output channel power gain flattened optical amplifier |
US6310716B1 (en) * | 2000-08-18 | 2001-10-30 | Corning Incorporated | Amplifier system with a discrete Raman fiber amplifier module |
US6657774B1 (en) * | 2000-08-18 | 2003-12-02 | Corning Incorporated | Amplifier system with distributed and discrete Raman fiber amplifiers |
JP4565794B2 (en) * | 2000-09-07 | 2010-10-20 | 富士通株式会社 | Optical amplification device and optical communication system |
KR100399578B1 (en) | 2000-11-29 | 2003-09-26 | 한국전자통신연구원 | Long Wavelength Band Erbium-doped fiber amplifier |
US20020163684A1 (en) * | 2000-12-13 | 2002-11-07 | Ar Card | Optical noise reduction apparatus and method |
US6687049B1 (en) * | 2001-07-03 | 2004-02-03 | Onetta, Inc. | Optical amplifiers with stable output power under low input power conditions |
US6728028B1 (en) * | 2001-07-30 | 2004-04-27 | Cisco Technology, Inc. | Low noise figure optical amplifier for DWDM systems with per sub-band power control |
KR100349007B1 (en) | 2001-09-07 | 2002-08-17 | Lg Cable Ltd | Low noise optical amplifying device and optical communication system using the same |
DE10144948B4 (en) * | 2001-09-12 | 2007-10-31 | Siemens Ag | Method for controlling a pump device with optical amplification of a transmitted wavelength division multiplexed (-WDM) signal |
US20030142388A1 (en) * | 2002-01-31 | 2003-07-31 | Sergey Frolov | Waveguide optical amplifier |
US6865018B2 (en) * | 2002-03-04 | 2005-03-08 | Inplane Photonics, Inc. | Multistage optical amplifier having a fiber-based amplifier stage and a planar waveguide-based amplifier stage |
KR100442624B1 (en) * | 2002-03-21 | 2004-08-02 | 삼성전자주식회사 | Gain flattening filter and gain flattened optical fiber amplifier using it |
JP4310971B2 (en) * | 2002-06-18 | 2009-08-12 | 日本電気株式会社 | Optical fiber amplifier |
GB2398922A (en) * | 2003-02-26 | 2004-09-01 | Bookham Technology Plc | Optical amplifiers |
US20040207912A1 (en) * | 2003-04-17 | 2004-10-21 | Nagel Jonathan A. | Method and apparatus for distributing pump energy to an optical amplifier array in an asymmetric manner |
US7361171B2 (en) | 2003-05-20 | 2008-04-22 | Raydiance, Inc. | Man-portable optical ablation system |
US20050038487A1 (en) * | 2003-08-11 | 2005-02-17 | Richard Stoltz | Controlling pulse energy of an optical amplifier by controlling pump diode current |
US9022037B2 (en) | 2003-08-11 | 2015-05-05 | Raydiance, Inc. | Laser ablation method and apparatus having a feedback loop and control unit |
US7367969B2 (en) * | 2003-08-11 | 2008-05-06 | Raydiance, Inc. | Ablative material removal with a preset removal rate or volume or depth |
US8173929B1 (en) | 2003-08-11 | 2012-05-08 | Raydiance, Inc. | Methods and systems for trimming circuits |
US8921733B2 (en) | 2003-08-11 | 2014-12-30 | Raydiance, Inc. | Methods and systems for trimming circuits |
US7115514B2 (en) * | 2003-10-02 | 2006-10-03 | Raydiance, Inc. | Semiconductor manufacturing using optical ablation |
US7143769B2 (en) * | 2003-08-11 | 2006-12-05 | Richard Stoltz | Controlling pulse energy of an optical amplifier by controlling pump diode current |
EP1531563B1 (en) * | 2003-11-14 | 2009-04-08 | Alcatel Lucent | Multiple order raman amplifier |
US7413847B2 (en) * | 2004-02-09 | 2008-08-19 | Raydiance, Inc. | Semiconductor-type processing for solid-state lasers |
US7349452B2 (en) * | 2004-12-13 | 2008-03-25 | Raydiance, Inc. | Bragg fibers in systems for the generation of high peak power light |
US7173756B2 (en) * | 2005-02-17 | 2007-02-06 | Jds Uniphase Corporation | Optical amplification system for variable span length WDM optical communication systems |
DE102005031897B4 (en) * | 2005-07-07 | 2007-10-25 | Siemens Ag | Multi-stage fiber amplifier |
EP1905139B1 (en) * | 2005-07-07 | 2009-06-24 | Nokia Siemens Networks Gmbh & Co. Kg | Multistage fibre amplifier and method for adapting a pump power of a multistage fibre amplifier |
US8135050B1 (en) | 2005-07-19 | 2012-03-13 | Raydiance, Inc. | Automated polarization correction |
US7245419B2 (en) | 2005-09-22 | 2007-07-17 | Raydiance, Inc. | Wavelength-stabilized pump diodes for pumping gain media in an ultrashort pulsed laser system |
US7308171B2 (en) | 2005-11-16 | 2007-12-11 | Raydiance, Inc. | Method and apparatus for optical isolation in high power fiber-optic systems |
ATE514242T1 (en) | 2005-11-21 | 2011-07-15 | Alcatel Lucent | OPTICAL TRANSMISSION SYSTEM AND OPTICAL FILTER STRUCTURE FOR UNDERWATER APPLICATION |
US7436866B2 (en) | 2005-11-30 | 2008-10-14 | Raydiance, Inc. | Combination optical isolator and pulse compressor |
US8232687B2 (en) | 2006-04-26 | 2012-07-31 | Raydiance, Inc. | Intelligent laser interlock system |
US8189971B1 (en) | 2006-01-23 | 2012-05-29 | Raydiance, Inc. | Dispersion compensation in a chirped pulse amplification system |
US9130344B2 (en) | 2006-01-23 | 2015-09-08 | Raydiance, Inc. | Automated laser tuning |
US7444049B1 (en) | 2006-01-23 | 2008-10-28 | Raydiance, Inc. | Pulse stretcher and compressor including a multi-pass Bragg grating |
US7822347B1 (en) | 2006-03-28 | 2010-10-26 | Raydiance, Inc. | Active tuning of temporal dispersion in an ultrashort pulse laser system |
US7940453B2 (en) * | 2006-08-07 | 2011-05-10 | Pyrophotonics Lasers Inc. | Fiber amplifiers and fiber lasers with reduced out-of-band gain |
JP5103963B2 (en) * | 2007-03-15 | 2012-12-19 | 日本電気株式会社 | Multistage optical amplifier and control method thereof |
US7903326B2 (en) | 2007-11-30 | 2011-03-08 | Radiance, Inc. | Static phase mask for high-order spectral phase control in a hybrid chirped pulse amplifier system |
US7911684B1 (en) * | 2008-03-07 | 2011-03-22 | Oplink Communications, Inc. | Variable gain erbium doped fiber amplifier |
US8125704B2 (en) | 2008-08-18 | 2012-02-28 | Raydiance, Inc. | Systems and methods for controlling a pulsed laser by combining laser signals |
KR20140018183A (en) | 2010-09-16 | 2014-02-12 | 레이디안스, 아이엔씨. | Laser based processing of layered materials |
US8554037B2 (en) | 2010-09-30 | 2013-10-08 | Raydiance, Inc. | Hybrid waveguide device in powerful laser systems |
WO2013145142A1 (en) * | 2012-03-27 | 2013-10-03 | 富士通株式会社 | Dispersion compensator |
US20150085352A1 (en) * | 2013-09-20 | 2015-03-26 | Alcatel-Lucent Usa Inc. | Optical amplifier for space-division multiplexing |
CA2978728C (en) | 2015-03-05 | 2023-08-01 | Nufern | Method and apparatus for providing amplified radiation |
US9899792B1 (en) * | 2016-08-19 | 2018-02-20 | Alcatel-Lucent Usa Inc. | Efficient pumping of an array of optical amplifiers |
US11323105B2 (en) | 2018-06-15 | 2022-05-03 | Fermi Research Alliance, Llc | Method and system for arbitrary optical pulse generation |
CN111697418B (en) * | 2019-03-13 | 2021-05-11 | 武汉奥新科技有限公司 | Single pump gain range switchable optical amplifier for optical fiber transmission |
CN113315598B (en) * | 2021-06-18 | 2023-12-15 | 福州高意通讯有限公司 | EDFA amplifier module with multi-optical fiber collimator |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA2019253C (en) * | 1989-06-23 | 1994-01-11 | Shinya Inagaki | Optical fiber amplifier |
US5115338A (en) * | 1990-05-30 | 1992-05-19 | At&T Bell Laboratories | Multi-stage optical amplifier |
EP0459685A3 (en) * | 1990-05-30 | 1993-12-01 | American Telephone & Telegraph | Multi-stage optical amplifier |
US5233463A (en) * | 1990-07-16 | 1993-08-03 | Pirelli Cavi S.P.A. | Active fiber optical amplifier for a fiber optics telecommunication line |
IT1246599B (en) * | 1991-04-15 | 1994-11-24 | Pirelli Cavi S P A Dir Proprie | ACTIVE FIBER OPTICAL AMPLIFIER FOR A FIBER OPTIC TELECOMMUNICATION LINE |
JP2734209B2 (en) * | 1991-01-28 | 1998-03-30 | 日本電気株式会社 | Optical fiber amplifier |
US5187610A (en) * | 1991-12-19 | 1993-02-16 | At&T Bell Laboratories | Low noise, optical amplifier having post-amplification loss element |
US5239607A (en) * | 1992-06-23 | 1993-08-24 | Bell Communications Research, Inc. | Optical fiber amplifier with flattened gain |
US5253104A (en) * | 1992-09-15 | 1993-10-12 | At&T Bell Laboratories | Balanced optical amplifier |
-
1993
- 1993-09-30 US US08/129,825 patent/US5430572A/en not_active Expired - Lifetime
-
1994
- 1994-07-12 CA CA002127946A patent/CA2127946A1/en not_active Abandoned
- 1994-08-30 KR KR1019940021500A patent/KR950010416A/en not_active Application Discontinuation
- 1994-09-21 EP EP94306934A patent/EP0647000A1/en not_active Withdrawn
- 1994-09-26 AU AU74224/94A patent/AU679098B2/en not_active Ceased
- 1994-09-28 JP JP6257360A patent/JPH07176817A/en active Pending
Also Published As
Publication number | Publication date |
---|---|
KR950010416A (en) | 1995-04-28 |
JPH07176817A (en) | 1995-07-14 |
EP0647000A1 (en) | 1995-04-05 |
AU679098B2 (en) | 1997-06-19 |
US5430572A (en) | 1995-07-04 |
AU7422494A (en) | 1995-04-13 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5430572A (en) | High power, high gain, low noise, two-stage optical amplifier | |
US6462862B2 (en) | Optical fiber amplifier and dispersion compensating fiber module for optical fiber amplifier | |
US5253104A (en) | Balanced optical amplifier | |
US6172803B1 (en) | Optical amplifier and transmission system using the same | |
US5392153A (en) | Optical amplifier | |
US20010012147A1 (en) | Optical fibre amplifier having a gain flattening filter | |
WO2002017518A1 (en) | Amplifier system with distributed and discrete raman fiber amplifiers | |
EP0782225B1 (en) | Low tilt, high gain fiber amplifier | |
US7346280B1 (en) | Bi-directional long haul/ultra long haul optical communication link | |
US5295217A (en) | Amplifier having an amplifying optical fiber | |
US6570701B1 (en) | Long-band light source for testing optical elements using feedback loop | |
US6532104B1 (en) | C-band and L-band optical amplifier for submarine transmission systems | |
CA2351268C (en) | Raman amplifier with gain enhancement from optical filtering | |
US6862132B1 (en) | Suppression of double rayleigh backscattering and pump reuse in a raman amplifier | |
US6606190B2 (en) | Inhomogeneity tunable erbium-doped fiber amplifier with long wavelength gain band and method of blocking propagation of backward amplified spontaneous light emission in the same | |
Smart et al. | Gain peaking in a chain of 980 nm-pumped erbium-doped fiber amplifiers | |
JP2002217477A (en) | Optical amplifier | |
US11764536B2 (en) | Optical amplifier for multiple bands | |
KR0183913B1 (en) | Erbium doped fiber amplifier having flat gain and low noise-figure | |
KR0183911B1 (en) | Optical fiber amplifier having flat gain and low noise-figure | |
KR0162758B1 (en) | Optical fiber amplifier | |
JPH0728106A (en) | Optical fiber amplifier and photo-signal transmitting system | |
Blondel et al. | Gain filtering in cascaded amplifier systems | |
Smart et al. | Effect of pumping configuration on noise figure and efficiency for 0.98-um-pumped saturated erbium-doped fiber amplifiers | |
KR980013063A (en) | Optical fiber amplifiers with low noise figure and flat gain |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
EEER | Examination request | ||
FZDE | Discontinued |