CN1416008A

CN1416008A - Optical fiber type variable optical attenuator

Info

Publication number: CN1416008A
Application number: CN02147794A
Authority: CN
Inventors: 黄秋元; 陈伟; 周鹏; 祁存荣
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT; Wuhan University of Science and Technology WHUST
Priority date: 2002-12-06
Filing date: 2002-12-06
Publication date: 2003-05-07
Anticipated expiration: 2022-12-06
Also published as: CN1176399C

Abstract

This invention relates to fiber light variable attenuator includes a shell with two fiber butt interfaces (2) a fiber (3) connecting the two fiber butt interfaces in the shell; a surrounding device enabling fiber (3) to form a ring with a control rod set at outside of the shell. The fiber generates fiber bending lost, which results in the variation form conductive mode to radiation mode of the light in the fiber. This invented fiber attenuator alters fiber surrounding circles or fiber carved radius to control the fiber curvature by the surrounding device using this theory to reach the aim of continuous attenuation of the output light with attenuation variation sphere of 0dB-70dB.

Description

The optical-fiber type variable optical attenuator

Technical field

The device that the present invention relates to use in the optical communication, particularly optical attenuator.

Background technology

Optical attenuator is a kind of very important fiberoptic passive device that occurs along with the development of optical communication industry, can be used for the aspect such as assessment, research and adjustment, correction of optical communication line, system, present market consumption is only second to the joints of optical fibre, fiber coupler.

According to the principle of work of optical attenuator, present optical attenuator can be divided into: displacement type optical attenuator, plated film type optical attenuator, attenuator type light decay spare device, liquid crystal type optical attenuator and opto-electronic conversion type optical attenuator etc.Wherein displacement type optical attenuator, liquid crystal type optical attenuator and opto-electronic conversion type optical attenuator are variable attenuation, but the complex structure of these optical attenuators, mechanical part precision prescribed height, cost height; Though plated film type light decay alkali device and attenuator type light decay spare device are simple in structure, just with fixed decay, function singleness.

Summary of the invention

Technical matters to be solved by this invention is: a kind of optical-fiber type variable optical attenuator simple in structure is provided.

The present invention solves the problems of the technologies described above the technical scheme that is adopted: it comprises shell, and shell is provided with two fiber alignment interfaces, and two fiber alignment interface end in the shell connect by optical fiber; Be provided with in the shell can make optical fiber form around around device, be arranged on housing exterior around the control lever of device.

Can produce bending loss of optical fiber during fibre-optical bending, this loss be light in optical fiber, guided modes is transformed to radiation mode and the loss that produces.Optical-fiber type optical attenuator of the present invention is to utilize this principle, by can make optical fiber form around around device, change fiber optic loop around the number of turns or the bending radius of optical fiber, control the flexibility of optical fiber, reach the purpose that light energy output is decayed enough continuously, and it is variable to decay, and attenuation range can reach 0dB-70dB.

Optical-fiber type optical attenuator of the present invention is simple in structure, and cost is low.

Description of drawings

Fig. 1 is the structural representation of the embodiment of the invention

Fig. 2 is the schematic appearance of the embodiment of the invention

Specific embodiments

The embodiment of the invention as shown in Figure 1, it comprises shell 1, and shell 1 is provided with two fiber alignment interfaces 2, and two fiber alignment interface 2 ends in the shell 1 connect by optical fiber 3.Be provided with in the shell 1 can make optical fiber 3 form around around device, control lever around device is arranged on shell 1 outside, wherein, be rotatable axle 4 around device, a bit being connected on the optical fiber 3 with axle 4, part optical fiber 3 is looped around on the axle 4, as crooked attenuating fiber section, can regulate by turning axle 4 around radius; Control lever is adjustable rotating disk 5, and axle 4 is connected with the center of circle of rotating disk 5.The forward and backward fiber lengths of optical fiber 3 circle segments is greater than 1 meter.Be provided with radius in the shell 1 greater than 16 millimeters fiber reel 7, the forward and backward optical fiber 3 of optical fiber circle segment is looped around on the fiber reel 7.

Shell 1 is provided with index dial 6, pointer in the index dial 6 with around device by link gear 8 interlock, two row scales are arranged on the index dial 6, be respectively the decay scale of 1310nm and 1550nm: regulate the critical conditions of rotating disk 5 to decay, axle 4 can cause light to decay in optical fiber 3, reads pad value from index dial 7.Index dial up and down two ends is provided with two solid obstacles point, makes the pointer in the index dial 6 can only be adjustable in this scope, avoids optical fiber 3 radius-of-curvature too small.

According to the D.Marcuse theory, when bending radius was R, bending loss was:

A_{b} = \frac{\sqrt{π} u^{2} \exp [- \frac{2}{3} (w^{3} / β^{2}) R]}{2 W^{\frac{3}{2}} V^{2} \sqrt{R} K_{m - 1} (Wa) K_{m + 1} (Wa)}

In the formula, u, W are respectively radially normalization phase constant of optical fiber and radially normalization attenuation constant; β is an axial propagation constant: α is a fiber core radius; V is a normalized frequency; Km is m rank modified Bessel functions.From formula as can be known, along with the increase of wavelength, the V value reduces, and bending loss increases.Therefore in the use of 1310nm and these two wavelength of 1550nm of optical communication, in the embodiment of the invention fibre-optical bending degree is converted into index dial 6 and is shown two row pad values.

Bending loss of optical fiber experimental data table

1550mm 1310mm

Bending radius splicing loss loss increases the splicing loss loss and increases

R/mm ∞/dB value ∞/dB ∞/dB value ∞/dB

16 1.02 0.01 1.00 0.00

15 1.14 0.13 1.00 0.00

14 1.18 0.17 1.00 0.00

13 1.30 0.29 1.00 0.00

12 1.37 0.36 1.00 0.00

10 1.47 0.46 1.02 0.02

9 4.22 3.21 1.11 0.11

8 5.63 4.62 1.30 0.30

7 7.57 6.56 1.50 0.50

6 9.75 8.74 2.00 1.00

5 can not survey very big by 4.57 3.57

After becoming fiber reel radius R to be respectively the garden circle of 16mm, 15mm, 14mm, 13mm, 12mm, 11mm, 10mm, 9mm, 8mm, 7mm, 6mm, 5mm at every turn, measure at 1310nm and two kinds of wavelength of 1550nm respectively again that it is as shown in the table, different R record splicing loss value difference, this is because different and different with degree of crook near the backscattering of joint, embodiment of the invention employing greater than 1 meter, can be eliminated this variation at the forward and backward fiber lengths of optical fiber 3 circle segments.

For increasing damping capacity, can decay around multi-turn, when the rack diameter was 8mm, 4 circles can be easy to reach the attenuation range of 0-70dB around around rack the time.

Can realize and being connected of distinct interface that fiber alignment interface 2 is SC (plug-in) flange or FC (spiral) flange by being equipped with different switching wire jumpers.

Claims

1, optical-fiber type Variable Optical Attenuator is characterized in that: it comprises shell (1), and shell (1) is provided with two fiber alignment interfaces (2), connects by optical fiber (3) between two fiber alignment interfaces (2) end in the shell (1); Be provided with in the shell (1) can make optical fiber (3) form around around device, be arranged on shell (1) outside around the control lever of device.

2, optical-fiber type Variable Optical Attenuator as claimed in claim 1 is characterized in that: be rotatable axle (4) around device, a bit being connected with axle (4) on the optical fiber (3).

3, optical-fiber type Variable Optical Attenuator as claimed in claim 2 is characterized in that: control lever is adjustable rotating disk (5), and axle (4) is connected with the center of circle of rotating disk (5).

4, optical-fiber type Variable Optical Attenuator as claimed in claim 1 is characterized in that: the forward and backward fiber lengths of optical fiber (3) circle segment is greater than 1 meter.

5, as claim 1 or 2 or 3 or 4 described optical-fiber type Variable Optical Attenuators, it is characterized in that: fiber alignment interface (2) is spiral flange or plug-in flange.

6, as claim 1 or 2 or 3 or 4 described optical-fiber type Variable Optical Attenuators, it is characterized in that: shell (1) is provided with index dial (6), the pointer in the index dial (6) with around device interlock.

7, optical-fiber type Variable Optical Attenuator as claimed in claim 6 is characterized in that: index dial (6) is marked with the above scale value of two row.

8, optical-fiber type Variable Optical Attenuator as claimed in claim 4 is characterized in that: be provided with fiber reel (7) in the shell (1), the forward and backward optical fiber (3) of optical fiber circle segment is looped around on the fiber reel (7).

9, optical-fiber type Variable Optical Attenuator as claimed in claim 8 is characterized in that: the radius of fiber reel (7) is greater than 16 millimeters.