WO2008019612A1

WO2008019612A1 - A common light source, wavelength division multiplexing passive optical network system and method for the system to share the light source

Info

Publication number: WO2008019612A1
Application number: PCT/CN2007/070416
Authority: WO
Inventors: Huafeng Lin; Tao Jiang; Jun Zhao; Guo Wei
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-08-15
Filing date: 2007-08-06
Publication date: 2008-02-21
Also published as: CN101127571A

Abstract

A common light source, wavelength division multiplexing passive optical network system and method for the system to share the light source are provided, the said common light source includes: a wide spectrum light source for generating wide spectrum light; a splitter for dividing the wide spectrum light of the said wide spectrum light source into multiple identical wide spectrum light, and providing the wide spectrum light to multiple wavelength division multiplexing passive optical network systems. In this invention, the wide spectrum light generated by the wide spectrum light source is filtered by the wide spectrum light band pass filter, then is input to the splitter after being amplified by the amplifier, multiple identical wide spectrum light sources generated by the splitter are output to respective wavelength division multiplexing passive optical network, so the application cost of the wavelength division multiplexing passive optical network is reduced.

Description

Public light source, wavelength division multiplexing passive optical network system and method for sharing the same. The present application claims to be filed on August 15, 2006, the Chinese Patent Office, the application number is 200610062125.2, and the invention name is "a WDM-PON system sharing. The method of sharing the common light source and the light source, the priority of the Chinese patent application, the entire contents of which is incorporated herein by reference. Technical field

The present invention relates to a wavelength division multiplexing sourceless optical network (WDM-PON), which relates to a common light source, a wavelength division multiplexing passive optical network system and a method for sharing the same.

Background technique

Currently, as users' demand for large data volumes increases, such as high definition digital television

(HDTV, High-definition digital television), Video on Demand (VOD), etc., the bandwidth demand of users' broadband access will reach 100Mbps or higher, using existing xDSL (digital subscriber line), HFC (Hybrid Fiber) -Coax, Hybrid Fiber Coax), LAN (Local Area Network) access methods will not meet the requirements.

On the other hand, with the maturity of optical fiber communication technology, the cost of optical fiber and optical devices has dropped drastically. Due to its huge bandwidth capacity, optical fiber has been favored by more and more telecom operators, and the demand for laying access networks with optical fibers is increasing. Rapid growth.

In the fiber access network, especially the Passive Optical Network (PON) is a hot spot. The passive optical network is a user access network that satisfies both the bandwidth requirements of new services and is economical and convenient to operate and maintain. The network structure of the PON is as shown in Figure 1. It includes an optical line terminal (OLT, Optical Line Terminal) 11 in the central office, an optical distribution network (ODN) 12, and many optical network units (ONU). , Optical Network Unit)13. Depending on the implementation, PON can be divided into ATM (Asynchronous Transfer Mode)-based ATM-PON, Ethernet-based EPON (Ethernet PON), and Gigabit Passive Optical Network (GPON). WDM-PON using wavelength division multiplexing and OCDDA-PON using Code Division Multiple Access (CDMA).

WDM-PON systems have attracted much attention due to their huge bandwidth capacity, information security like point-to-point communication, and simple network structure, but WDM-PON networks for laser sources, modulators, arrayed waveguide gratings (AWG, Array Waveguide) Grating), etc. are very demanding, and the cost has been Staying high has become a bottleneck that hinders its promotion and application.

In order to reduce the light source cost of the WDM-PON system, and to achieve the colorlessness of the ONU, that is, independent of the specific wavelength, a mainstream solution is to use a wide-spectrum light source and a lock-wave light source, as shown in FIG. 20 has two broad-spectrum light sources, a broad-spectrum light source 1 and a broad-spectrum light source 2, which satisfy the FSR (Free Spectrum Range) relationship of the multiplexer/demultiplexer. After the spectral light source passes through the spectral line dividing function of the multiplexing/demultiplexing devices 22 and 24, the seed light source is respectively provided for each of the lock wave light sources; wherein the wide spectrum light source 1 is each of the OLT (Optical Line Terminal) 201 The downlink lock-wave source 21 provides a seed source, and the broad-spectrum source 2 provides a seed source for the upstream lock-wave source 23 of each ONU (Optical Network Unit) 203. The lock-wave source may be an RSO A (Reflective Semiconductor Optical Amplifier) or a Reflective FP-LD (Faby Perot Laser).

In practical applications, since the power of the wide-spectrum light source is relatively small, the optical amplifier is required to amplify the optical power of the broad-spectrum light source to meet the minimum incident optical power requirement of the lock-wave light source, thereby causing an increase in cost. In addition, the two broad-spectrum light sources and optical amplifiers are limited to the same WDM-PON network share, so the sharing is not high.

In order to realize a low-cost WDM-PON system, a technical solution of a tunable light emitting module is also used in the prior art. The system is shown in FIG. 3. The data control center 301 on the ONU 31 identifies the receiver 304. Whether the downlink data is a wavelength control message or a downlink user data. If a wavelength control message from the OLT 32 is received, the transmission wavelength of the tunable optical transmission module 303 is adjusted to a wavelength specified by the wavelength control message through the wavelength control center 302. , thereby achieving colorlessness of the ONU.

The dimming transmitter module in the above solution requires a subsidiary device such as a temperature control and a wavelength calibration device, so the cost reduction is not obvious.

In order to further improve the sharing degree of the light source and thereby reduce the cost of the light source, the prior art also has a light source solution of a multi-wavelength laser combining wavelength division multiplexing and time division multiplexing (TDM), as shown in FIG. 4 . Shown. In this solution, the WDM-TDM multi-wavelength laser 41 continuously generates laser light of different wavelengths in a time-division manner, and then passes through the optical amplifier 42 and the branching unit 43, and supplies a laser source to the external modulator 44 of each WDM-PON. The external modulator 44 must modulate the data of different users at different times depending on the wavelength variation of the WDM-TDM multi-wavelength laser. This solution requires a strict synchronization mechanism and a complex multiplexing scheduling mechanism, and since the different wavelengths share a multi-wavelength laser in a TDM manner, the switching time of the multi-wavelength laser is very high, resulting in a multi-wavelength laser being expensive. In addition, as the number of users, that is, the number of wavelengths and user bandwidth increases, multi-wavelength lasers will eventually fail to meet the requirements.

Summary of the invention

Embodiments of the present invention provide a common light source that provides light source sharing for multiple WDM-PON systems to reduce the cost of the WDM-PON system.

Embodiments of the present invention also provide a wavelength division multiplexing passive optical network system and a method for sharing the same, to reduce system cost.

A public light source provided by an embodiment of the present invention includes:

a broad spectrum source for generating broad spectrum light;

a branching device, configured to divide the broad-spectrum light from the broad-spectrum light source into a plurality of identical broad-spectrum lights, and output the divided plurality of identical broad-spectrum lights to a plurality of wavelength-division multiplexed passive lights Network Systems.

A method for sharing a light source in a WDM-PON system according to an embodiment of the present invention includes: a wide-speaking light source generating wide-speech light, and outputting the broad-spectrum light to a brancher;

After receiving the wide-spectrum light, the brancher divides it into multiple copies of the same wide-spectrum light and outputs it to a plurality of wavelength division multiplexing passive optical network systems;

The plurality of wavelength division multiplexed passive optical network systems perform transmission of data using the received wide spectrum light.

A wavelength division multiplexing passive optical network system system provided by an embodiment of the present invention includes: a plurality of optical line terminals, each optical line terminal being connected to a plurality of optical network units through a fiber distribution network, where the system further includes :

An uplink common light source for generating broad spectrum light, and outputting the broad spectrum light into a plurality of identical broad spectrum lights to the plurality of optical line terminals, and forwarding, by the optical line terminal, the plurality of optical fiber distributions a network for the plurality of fiber distribution networks to spectrally split the laser light required to transmit uplink data of the optical network unit connected to the fiber distribution network;

a downlink common light source for generating broad-spectrum light, and outputting the broad-spectrum light into a plurality of identical broad-spectrum lights to the plurality of optical line terminals for segmentation of the plurality of optical line terminals for transmission The laser light required for the downlink data of the optical line terminal. In the embodiment of the invention, the wide-spectrum light generated by the broad-spectrum light source is used as a common light source, and the splitter is divided into a plurality of identical broad-spectrum light sources and output to each WDM-PON system, so that each WDM-PON system can share the light source, thereby reducing WDM. - PON application cost.

DRAWINGS

Figure 1 is a structural diagram of an existing PON system;

2 is a system diagram of a WDM-PON in which a wide-spectrum light source is used in the prior art;

3 is a system diagram of a WDM-PON using a tunable light source in the prior art;

4 is a diagram of a WDM-PON system of a multi-wavelength laser using wavelength division multiplexing and time division multiplexing in the prior art;

FIG. 5 is a structural diagram of a common light source according to an embodiment of the present invention; FIG. 7 is a diagram of a WDM-PON system for a common light source for use in an embodiment of the present invention.

detailed description

Embodiments of the present invention provide a common light source for a plurality of WDM-PON systems, so that multiple WDM-PON systems share a light source. Specifically, the broad spectrum light is generated by the broad spectrum light source, filtered by the optical band pass filter, and then amplified by the amplifier and input to the branching device. The splitter is divided into a plurality of identical wide spectrum light sources and output to each WDM-PON system.

The details are described below in conjunction with the drawings and specific embodiments.

A common light source of an embodiment of the invention is shown in FIG. 5:

The common light source 50 includes: a broad spectrum light source 501 for generating broad spectrum light, and a splitter 502 for dividing the broad spectrum light from the broad spectrum light source 501 into a plurality of identical broad spectrum lights. .

In order to make the plurality of copies of the same wide-spectrum light output by the common light source 50 have better characteristics, the optical band pass filter 503 and the optical amplifier 504 may be disposed in the common light source 50. The optical bandpass filter 503 is used to filter the broad spectrum light generated by the broad spectrum light source 501; the optical amplifier 504 is used to optically amplify the broad spectrum light generated by the broad spectrum light source 501.

In this embodiment, the wide-spectrum light generated by the broad-spectrum light source 501 passes through the optical band-pass filter 503, is amplified by the optical amplifier 504, and then splits into N identical identical broad-spectrum light sources through the splitter 502, and outputs the output to each. WDM-PON is used. In public light sources, to prevent wide-spectrum light source failure For communication, a backup light source 505 can also be designed. When the broad spectrum light source fails, the backup light source starts to work, and is coupled to the optical band pass filter through the coupler 506 to complete the function of the broad spectrum light source.

The branch of the common light source is not limited to one level, and the method of multi-level branching can be used to further increase the sharing degree of the public light source. As shown in Fig. 6, a common light source using two-stage branches is used.

The difference from the embodiment shown in FIG. 5 is that, in this embodiment, the wide-spectrum light generated by the broad-spectrum light source 501 in the common light source 60 passes through the optical band-pass filter 503, and is amplified by the first-stage optical amplifier 61. Then, the first-stage splitter 62 is divided into a plurality of identical wide-spectrum light sources, wherein the first wide-spectrum light is directly sent to one WDM-PON, and the second wide-spectrum light passes through the second-stage optical amplifier 63. The amplification is then divided into a plurality of identical wide-spectrum light sources through the second-stage splitter 64, and the output is sent to a plurality of WDM-PONs for use.

In this embodiment, a common light source using two-stage branches is shown, and in this manner, a common source of multi-stage branches can also be used. It can be seen that the common light source provided by the embodiment of the present invention can provide light source sharing for multiple WDM-PON systems at a low cost, thereby reducing the cost of the WDM-PON system.

The wide-spectrum light source in the above common light source may be a light emitting diode (LED), a super-luminescent LED (SLED), or an amplified spontaneous emission (ASE).

In the common light source, an optical amplifier may be an erbium doped fiber amplifier (EDFA, erbium-doped fiber amplifier ) ¾ semiconductor amplifier (SOA, semiconductor optical amplifier), or Raman amplifiers.

In the above common light source, the spectral division of the wide-spectrum light source input into each WDM-PON can be realized by an AWG (Array Waveguide Grating), and after the AWG spectral line division, the broad-spectrum light source is divided into wavelengths respectively. For narrowband lasers of λΐ, ..., λη, the wavelength spacing is determined by the channel spacing of the AWG.

In the above common light source, after the amplified wide-spectrum light source is divided into wide-spectrum light sources with small power by the branching device, in order to ensure a sufficiently long transmission distance and a sufficiently large injection power, the spectrum is entered into each WDM-PON system. Before the splitting, you can perform another light amplification.

By using the above common light source, a simple, low-cost WDM-PON system can be constructed, such as In this system, there are two common light sources, a down common light source 71 and an upcoming common light source 72. The downlink common light source 71 is configured to provide a downlink wide-spectrum light source for the OLT 70 of each WDM-PON system, and the wide-spectrum light output by the downlink common light source 71 is amplified by the optical amplifier 701 in the OLT 70, and then by a spectral splitter (which may be an AWG) 702 The amplified broad-spectrum light is segmented to obtain laser light having wavelengths of λΐ, λ2, ... λη, and then modulated by the modulator array 703 to the laser of wavelengths λΐ, λ2, ... λη The intermediate transmission is sent to each ONU, and the downlink light carrying the user data is transmitted to the receiver of each ONU through the ODN, thereby completing the transmission of the downlink data.

The uplink common light source 72 provides an uplink light source for the ONU located on the user side of the WDM-PON system, and the wide spectrum light output by the uplink common light source 72 is amplified by the optical amplifier 704 in the OLT 70, and then transmitted to the 705 and the circulator 706 through the coupler 705 and the circulator 706. The AWG73 of the remote node, after the line division of the AWG73, will provide each ONU 74 with a laser for transmitting uplink data. In the structure of FIG. 7, since the feeder fiber is a single fiber and there is only one AWG on the far node, the wide spectrum source 710 in the down common light source 71 and the wide spectrum source 720 in the upside common source satisfy the AWG. The periodic nature of the free spectral range FSR (Free Spectrum Range). Therefore, after the line division of the AWG, each ONU 74 will receive lasers having wavelengths of λΙ+FSR, ..., λη+FSR, respectively, and after loopback modulation by the ONU 74, will be sent back through the ODN network. The uplink receiving module 707 of the OLT 70 completes the uplink data transmission. Among them, the ONU loopback modulation can be implemented by using an injection-locked Fabry-Perot laser FP-LD laser (injection locked FP-LD) or RSOA as a direct modulation laser.

The following is a description of the workflow of the WDM-PON system composed of the common light source of the present invention: When transmitting downlink data, the wide-spectrum light generated by the wide-spectrum light source 710 in the downlink common light source 71 is filtered by the optical band-pass filter 711 and input to The optical amplifier 712 performs amplification, and the amplified broad-spectrum light is input to the branching device 713, and the branching device 713 divides the input wide-spectrum light into a plurality of identical broad-spectrum lights, and each of the broad-spectrum lights is input to a WDM-PON. In the OLT 70, each OLT 70 amplifies the received wide-spectrum light through the optical amplifier 701, and then inputs it to the spectral divider 702 for segmentation, and divides the broad-spectrum light into laser beams having wavelengths of λ1, λ2, ... λη, and then Through the modulator array 703, the downlink unicast data of each user is separately modulated into the narrowband lasers with the wavelengths λ1 λ λ η respectively, and the downlink light carrying the user data is transmitted to the receiver 741 of each ONU 74 through the ODN, as shown in FIG. 7 . As shown, the laser with a wavelength of λΐ is transmitted to the ONU1, and the laser with a wavelength of λ2 is transmitted to the ONU2, and the wavelength is λη. The optical transmission to the ONUn, the receiver 741 in each ONU 74 completes the photoelectric conversion and demodulation function of the optical signal carrying the downlink data of the ONU user, and recovers the downlink data of the user, thereby completing the downlink data transmission.

When the uplink data is transmitted, the wide-spectrum light generated by the wide-spectrum light source 720 in the upstream common light source 72 is filtered by the optical band-pass filter 721, input to the optical amplifier 722 for amplification, and the amplified broad-spectrum light is input to the branching device 723. The brancher 723 divides the input wide-spectrum light into a plurality of identical wide-spectrum lights, and each of the broad-spectrum lights is input to an OLT 70 of a WDM-PON, and each OLT 70 amplifies the received wide-spectrum light through an optical amplifier 704. Then, it is transmitted to the remote AWG 73 through the coupler 705 and the circulator 706 for segmentation to generate lasers having wavelengths of (λΐ + FSR) and (2+FSR) (λη+FSR), respectively. After the ONU 74 receives the light of the wavelength (λη+FSR), the loopback modulation unit 742 performs injection locking or reflection amplification on the received laser to generate laser light, and simultaneously modulates the uplink data to the injection locking or reflection amplification. In the laser, the upstream light carrying the uplink data of the user is sent back to the remote AWG 73, and the AWG 73 receives the optical signals carrying the uplink data of each user from each ONU 74, respectively, and is +FSR)~(n+FSR) optical signals, and then The optical signals having wavelengths of +FSR)~(n+FSR) are combined into one upstream mixed light, and transmitted to the circulator 706 of the OLT 70, and then transmitted to the upstream data processing module 707 in the OLT for subsequent processing.

After receiving the uplink mixed light from the ODN, the uplink data processing module 707 of the OLT 70 passes through the multiplexing demultiplexer AWG, and separates the optical signals having the wavelengths (λΙ+FSR) (λη+FSR), respectively, and sends them to different signals. The photoelectric conversion and demodulation device recovers the uplink data of each user.

It can be seen that, in the embodiment of the present invention, the wide-spectrum light generated by the broad-spectrum light source is used as a common light source, and the splitter is divided into a plurality of identical broad-spectrum light sources and output to each WDM-PON system, so that each WDM-PON system can share the light source, thereby The application cost of the WDM-PON is reduced. In addition, the common light source of the WDM-PON system of the embodiment of the present invention is continuous, and does not require a synchronization and scheduling mechanism, which is beneficial to the implementation and application of the system.

The above is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or within the technical scope disclosed by the present invention. Alternatives are intended to be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the claims.

Claims

Rights request

A common light source, wherein the light source comprises:

a broad spectrum source for generating broad spectrum light;

2. The common light source according to claim 1, wherein the light source further comprises: an optical amplifier for optically amplifying the broad spectrum light generated by the broad spectrum light source.

3. The common light source according to claim 1, wherein the light source further comprises: an optical band pass filter for filtering the broad spectrum light generated by the wide spectrum light source.

The public light source according to any one of claims 1 to 3, wherein the light source further comprises:

A backup source is used to generate broad spectrum light in place of the broad spectrum source when the broad spectrum source fails.

A method for sharing a light source by a wavelength division multiplexing passive optical network system, wherein the method comprises:

The wide-sense light source produces wide-speech light and outputs the broad-spectrum light to the splitter;

After receiving the wide-spectrum light, the branching device divides the wide-spectrum light into a plurality of identical broad-spectrum lights and outputs the same to a plurality of wavelength division multiplexing passive optical network systems;

6. The method according to claim 5, wherein the method further comprises: performing optical power amplification on the broad spectrum light before outputting the broad spectrum light to the branching device.

The method according to claim 5, wherein the step of the plurality of wavelength division multiplexed passive optical network systems to complete the transmission of the data by using the received wide spectrum light comprises:

The optical line terminal of the wavelength division multiplexing passive optical network system performs spectral division on the received wide-spectrum light to obtain laser beams of different wavelengths, and modulates the downlink data into the laser beams of different wavelengths and transmits the signals to the wave. The optical network unit of the multiplexed passive optical network system completes the transmission of the downlink data; or the optical line terminal of the wavelength division multiplexed passive optical network system forwards the received wide spectrum light to the optical fiber distribution network, and allocates the optical fiber The network spectrally splits the broad spectrum light from the optical line terminal, and transmits the split laser beams of different wavelengths to different optical network units, the laser of the optical network unit Performing injection locking or reflection amplification on the received laser to generate laser light, and modulating the uplink data into the laser generated by the injection locking or reflection amplification, and transmitting the laser carrying the data back to the wavelength division multiplexing passive The optical line terminal of the optical network system completes the transmission of the uplink data.

The method according to claim 7, wherein the step of the plurality of wavelength division multiplexed passive optical network systems to complete the transmission of the data by using the received wide spectrum light further comprises:

The wide spectrum light is optically amplified before the optical line terminal divides the received wide spectrum light.

The broad spectrum light is optically amplified before the fiber distribution network segments the received broad spectrum light.

A wavelength division multiplexing passive optical network system, comprising: a plurality of optical line terminals, each optical line terminal being connected to a plurality of optical network units through a fiber distribution network, wherein the system further comprises: An uplink common light source for generating broad spectrum light, and outputting the broad spectrum light into a plurality of identical broad spectrum lights to the plurality of optical line terminals, and forwarding, by the optical line terminal, the plurality of optical fiber distributions a network for the plurality of fiber distribution networks to spectrally split the laser light required to transmit uplink data of the optical network unit connected to the fiber distribution network;

a downlink common light source for generating broad-spectrum light, and outputting the broad-spectrum light into a plurality of identical broad-spectrum lights to the plurality of optical line terminals for segmentation of the plurality of optical line terminals for transmission The laser light required for the downlink data of the optical line terminal.

The system according to claim 10, wherein the downlink common light source and the uplink common light source each comprise:

a broad spectrum source for generating broad spectrum light;

A splitter for splitting the broad spectrum light from the broad spectrum source into a plurality of identical broad spectrum lights.

The common light source according to claim 10, wherein the downlink common light source and the uplink common light source further comprise:

An optical bandpass filter for filtering the broad spectrum light produced by the broad spectrum source.

13. The system of claim 10, wherein the upstream common light source and the lower common light source satisfy periodic characteristics of a free spectral range of the arrayed waveguide grating.