WO2011147245A1

WO2011147245A1 - Optical interleaving filtering device and method for realizing function of polarization wave-combining

Info

Publication number: WO2011147245A1
Application number: PCT/CN2011/073360
Authority: WO
Inventors: 李朝晖; 吕超; 曾理; 程凌浩; 杨彦甫; 刘磊
Original assignee: 华为技术有限公司
Priority date: 2010-05-27
Filing date: 2011-04-27
Publication date: 2011-12-01
Also published as: CN102262303B; CN102262303A

Abstract

An optical interleaving filtering device and method for realizing the function of polarization wave-combining are provided. The optical interleaving filtering device includes: a polarization wave-combiner (21,31,32), an optical circulator (22,33,34) and a section of polarization maintaining optical fiber (23,35,36) engraved with Bragg gratings (24,241,351,352,361,362). The polarization wave-combiner (21,31,32) is provided with an input end (26) of X polarization direction and an input end (27) of Y polarization direction, and the output end (211,B1,C1) of the polarization wave-combiner (21,31,32) is connected with any end of the polarization maintaining optical fiber (23,35,36) via the optical circulator (22,33,34) whose output end (A3,B3,C3) is used as the output end of the device. The optical interleaving filtering device has a simple structure and can save cost, and the performance of the wave divided multiplexing system is improved.

Description

Optical interlacing filtering device and method for realizing polarization multiplexing function The present application claims to be submitted to the Chinese Patent Office on May 27, 2010, and the application number is 201010187514. 4 , the invention name is "optical interleaving filtering device and method for realizing polarization multiplexing function" The priority of the Chinese Patent Application, the entire contents of which is incorporated herein by reference. Technical field

The present invention relates to the field of communications, and in particular, to an optical interleaving filtering apparatus and method for implementing a polarization combining function. Background technique

In recent years, the demand for transmission service capacity of the backbone optical transmission network has increased sharply, and the patterns that use the polarization characteristics of light to carry information or improve performance are endless, especially in the transmission of submarine cables, the adjacent channels are polarization-orthogonal communication. The system can improve the performance of the long-distance fiber transmission system more effectively, but the modulation pattern that needs special polarization processing for these adjacent channels cannot be realized by ordinary optical multiplexing and demultiplexing devices, so it is necessary to realize a performance price. An optical interlacing comb filter capable of realizing polarization multiplexing while at the same time.

The optical interlacing comb filter element capable of realizing the polarization multiplexing function is mainly operated by MZI (Mach-Zehnder interferometer) in a cascade manner and Mi cheson (McGerson interferometer) interference. achieve. The device costs are high and the performance is not excellent.

Figure 1 shows the device implemented based on the MZI cascading mode. The signal light passes through the MZI cascade device, which cascades through three optical paths (optical paths 1, 2, 3), each of which contains more MZI (such as Cl, C2 and C3 in the optical path 1 in Fig. 1), through the series connection of MZI, the periodic transmission spectrum of the passband wavelength interleaving is obtained at the odd and even ends of the output, thereby realizing the optical interlacing comb filtering. By adjusting the number of MZIs and the period interval, a comb filter spectrum with different periods and different transmission spectrum shapes can be obtained. However, due to the inability to achieve polarization retention, polarization for adjacent channels Orthogonal signals cannot be polarized.

Figure 2 shows the block diagram of the optical interleaving filter based on Mi chelson interference. The input light is input into the interferometer from the input and output end 6 of the left end face, passes through 50% of the transflective film 5, and a part of the light penetrates into the air gap cavity of the high reflective film layer 7 on the right side of the right side. The inside of the 3 is deflected, and the reflected light passes through 50% of the transflective film 5 to reach one of the output ends 4. Another portion of the light reflected by the transflective film to the upper end is reflected by the air gap chamber 2 of the high reflection film 1, and then the original path is returned to the other output terminal 6. Since the cavity lengths of the two air gap chambers 2 and 3 are different by 1/4 wavelength, the entire optical path differs by 1/2 wavelength, so the transmittance spectra of the two air gap chambers 2 and 3 are opposite. By adjusting the cavity length of the two air gap chambers 2, 3, the period of the comb spectrum can be adjusted to realize optical interlaced comb filters of different periods. This filter uses free space, although the polarization is well maintained, but the cost is too high, and the insertion loss is larger than other methods.

From the above description of the existing optical interlaced comb filter device, the existing optical interlaced comb filter device has at least the following problems:

The function of polarization preservation cannot be well realized, and the signals with orthogonal polarization of adjacent channels cannot be polarized and combined; or the structure is complicated, the volume is large, the cost is too high, and the insertion loss is relatively large. Summary of the invention

Embodiments of the present invention provide an optical interlace filtering device that implements a polarization combining function, which can simultaneously implement polarization multiplexing and optical interleaving filtering functions with fewer devices, thereby reducing device cost.

An embodiment of the present invention provides an optical interlace filtering device that implements a polarization multiplexing function, including: a polarization combiner, an optical circulator, and a polarization maintaining fiber; wherein the polarization maintaining fiber is provided with a Bragg grating;

The polarization combiner is provided with an X polarization direction input end, a Y polarization direction input end and an output end, and an output end of the polarization combiner is connected to the optical circulator for using an X or Y polarization state of Outputting the output to the optical circulator;

The polarization-maintaining fiber is connected at one end to the optical circulator for receiving the combined optical signal output by the polarization combiner through the optical circulator, and passing the Bragg grating pair on the polarization maintaining fiber The received optical signal is reflected and filtered to complete optical interlaced filtering, and the filtered optical signal is output through the output port of the optical circulator;

The output port of the optical circulator serves as an output of the interleaved filtering device.

An embodiment of the present invention further provides an optical interlace filtering method for implementing a polarization multiplexing function, including: inputting an optical signal having an X or Y polarization state from an X polarization direction input end or a Y polarization direction input end of a polarization combiner Combining to the polarization combiner;

The optical signal output after the multiplexed wave is input to the polarization maintaining fiber provided with the Bragg grating through the optical circulator, and the input optical signal is reflected and filtered by the Bragg grating on the polarization maintaining fiber to complete optical interleaving filtering of the optical signal. ;

The filtered optical signal is output through an output port of the optical circulator.

An embodiment of the present invention further provides an optical interlace filtering device that implements a polarization multiplexing function, including:

Two polarization splitters, two polarization combiners, two optical circulators, two polarization maintaining fibers, and a polarization maintaining fiber coupler; wherein each of the polarization maintaining fibers is provided with a Bragg grating;

Each polarization splitter has an input end and two output ends;

The two output ends of the first polarization splitter are respectively connected to the X polarization direction input end of the first polarization combiner and the Y polarization direction input end of the second polarization combiner, and are used for the light of the odd wave channel. The signal is divided into an X-polarized light signal and a Y-polarized light signal, and output to the first and second polarization combiners, respectively;

The two output ends of the second polarization combiner are respectively connected to the γ polarization direction input end of the first polarization combiner and the X polarization direction input end of the second polarization combiner, for dividing the optical signal of the even wave channel into An X-polarized light signal and a Y-polarized light signal are respectively output to the first and second polarization combiners;

Each polarization combiner is provided with an X polarization direction input terminal, a Y polarization direction input terminal and an output The output ends of the two polarization combiners are respectively connected to two optical circulators; each polarization combiner is used for an X-polarized light signal and a Y-polarization input from the X-polarization direction input end and the Y-polarization direction input end; The state optical signals are combined and output to the connected optical circulator;

The two polarization maintaining optical fibers are respectively connected to the two optical circulators; each polarization maintaining optical fiber is configured to receive a combined optical signal outputted by a polarization combiner through the connected optical circulator, and the polarization maintaining The Bragg grating on the optical fiber reflects and filters the received optical signal to complete optical interlaced filtering, and the filtered optical signal is output to the polarization maintaining fiber coupler through an output port of the connected optical circulator;

The output ports of the two optical circulators are respectively connected to the polarization maintaining fiber coupler as an output end of the optical interleaver filtering device.

The embodiment of the present invention further provides an optical interlace filtering method for implementing a polarization multiplexing function, comprising: dividing an optical signal of a odd wave channel into an X polarization state light signal and a Y polarization state light signal by using a first polarization splitter; The optical signal of the wave channel is divided into an X-polarized light signal and a Y-polarized light signal by a second polarization splitter;

Inputting the X-polarized light signal of the odd-wave channel obtained by the separation and the Y-polarized optical signal of the even-wave channel to the first polarization combiner for combining and outputting to the first optical circulator;

The optical signal output after the multiplexed wave is input to the first polarization-maintaining fiber provided with the Bragg grating through the first optical circulator, and the input optical signal is reflected and filtered by the Bragg grating on the first polarization-maintaining fiber, and the pair is completed. Optical interleaved filtering of optical signals;

Inputting the X-polarized light signal of the odd-wave channel obtained by the separation and the Y-polarized optical signal of the even-wave channel to the second polarization combiner for combining and outputting to the second optical circulator;

The optical signal output after multiplexing is input to the second polarization maintaining fiber provided with the Bragg grating via the second optical circulator, and the input optical signal is reflected and filtered by the Bragg grating on the second polarization maintaining fiber to complete the pair Optical interleaved filtering of optical signals;

The optical signals outputted by the first and second polarization-maintaining fibers are respectively outputted to an polarization-maintaining fiber coupler via the output ports of the first and second optical circulators for coupling output.

It can be seen from the technical solutions provided by the foregoing embodiments of the present invention that the embodiments of the present invention are The super-polarization combiner is matched with the polarization-maintaining fiber provided with the Bragg grating through the optical circulator, and the optical signal after the polarization of the polarization combiner is reflected and filtered by the Bragg grating provided on the polarization-maintaining fiber to complete the optical signal. Optical interleaved filtering. The device realizes polarization orthogonal multiplexing and optical interleaving filtering with fewer devices, and has the characteristics of simple structure, few devices and saving device cost. Used in optical networks to improve the performance of WDM systems. DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. It is obvious that the drawings in the following description are only Some embodiments of the invention may be obtained by those of ordinary skill in the art in view of the drawings without departing from the scope of the invention.

1 is a schematic diagram of a cascading MZI-based optical interlace filter provided by the prior art; FIG. 2 is a schematic diagram of an optical interleaver filter based on a Mi cheson interference method provided by the prior art;

3 is a schematic diagram of an optical interlace filtering device for implementing a polarization multiplexing function according to Embodiment 1 of the present invention;

4 is a schematic diagram of an optical interlace filtering device for implementing a polarization multiplexing function according to Embodiment 2 of the present invention;

FIG. 5 is a schematic diagram of interlaced filtering used in a polarization orthogonal multiplexing system according to Embodiment 2 of the present invention. detailed description

For the sake of understanding, the technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of them. Example. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts are Within the scope of the protection of the invention.

Embodiment 1

The embodiment provides an optical interlace filtering device for implementing a polarization multiplexing function, which can be used in a polarization multiplexing system. As shown in FIG. 3, the device includes:

The polarization combiner 21, the optical circulator 22 and the polarization maintaining fiber 23, wherein the polarization maintaining fiber 23 is provided with a Bragg grating (FBG, F i ber Bragg Grat ing), specifically, a fast and slow axis of the polarization maintaining fiber 23 The Bragg gratings 24 and 241 are written on the upper side, and the Bragg gratings 24 and 241 can respectively reflect the X-polarized light signal and the Y-polarized light signal; in practice, the fast-and-slow-axis Bragg grating of the polarization-maintaining fiber 23 is required. The frequency difference of the center frequency of the reflected spectrum matches the frequency difference of adjacent odd and even channels in the applied communication system;

The polarization combiner 21 is provided with an X polarization direction input end 26, a Y polarization direction input end 27 and an output end 211, and the X polarization direction input end 26 of the polarization combiner 21 corresponds to the odd wave optical signal 28, and the polarization combiner 21 The Y polarization direction input terminal 27 corresponds to the even wave optical signal 29. The odd and even wave optical signals 28 and 29 are orthogonal to the polarization state, and the polarization directions thereof are represented by X and Y, respectively, and the X and Y polarization state optical signals can be polarized and combined by the polarization combiner 21.

The output end 211 of the polarization combiner 21 is connected to either end of the polarization maintaining fiber 23 via the optical circulator 22;

The optical circulator 22 is provided with three ports A1, A2 and A3, which operate in such a manner that the optical signal can only be input from the first port A1, output from the second port A2, or the optical signal can only be input from the second port A2. , output from the third port A3, and vice versa;

An output end of the polarization combiner 21 is connected to the first port A1 of the optical circulator 22, and a second port A2 of the optical circulator 22 is connected to either end of the polarization maintaining fiber 23. The optical circulator 22 is Three port A 3 serves as the output of the optical interlace filtering device.

The optical circulator 22 in the above apparatus may employ an optical circulator having a polarization maintaining function.

In the above device, the Bragg grating written on the fast and slow axes of the polarization maintaining fiber can be realized by patterning the same mask pattern on the fast and slow axes of the polarization maintaining fiber, because of the refractive index of the fast and slow axis of the polarization maintaining fiber. There is a difference, therefore, by controlling the refractive index difference Δ η of the fast and slow axes of the polarization maintaining fiber In order to control the transmission transmittance spectrum of the two axial directions of the polarization maintaining fiber, the function of optical interlacing comb filtering can be realized.

There are different transmission transmittance spectra for adjusting the two axial directions of the polarization-maintaining fiber, which can be achieved in the following ways:

The frequency difference of the Bragg grating reflection spectrum written on the fast and slow axes of the polarization maintaining fiber 23 can be selected from the phase in the applied communication system by selecting the refractive index difference Δ η between the fast and slow axes of the polarization maintaining fiber 23. The frequency differences of the adjacent odd and even wave channels match. For polarization-maintaining fibers, the difference in refractive index Δ η between the fast and slow axes can be determined by the materials and structures used for polarization-maintaining fibers.

It is also possible to use a polarization maintaining fiber which can finely adjust the refractive index difference Δ η between the fast and slow axes by the applied stress. In application, the refractive index difference Δ η between the fast and slow axes of the polarization-maintaining fiber is finely adjusted by the applied stress, so that the polarization-maintaining fiber matches the frequency difference of the adjacent odd and even-wave channels in the applied communication system. By adjusting the stress to finely adjust the refractive index difference Δ η between the fast and slow axes of the polarization-maintaining fiber, it can adapt to the dynamic requirements of the communication system.

The polarization combiner in the above device combines two optical signals with orthogonal polarizations, and then performs reflection and filtering through the optical circulator and the polarization maintaining fiber, thereby realizing the polarization maintaining effect on the optical signals of the odd and even channels. , the device enables both polarization preservation and optical interlacing filtering.

The optical interleave filtering device in this embodiment is a device which realizes an integrated optical interlace filter and a polarization combiner function by using a polarization combiner and a polarization maintaining fiber written with a Bragg grating, and can be used with fewer devices. At the same time, the functions of the polarization maintaining multiplexed wave and the optical interlacing comb filter are realized, and the device cost is effectively saved under the premise of ensuring performance. Due to the maturity of the Bragg grating technology and the low cost of the polarization combiner, the cost of the device can be controlled to less than $1,000, which is much lower than the current optical interleaving filter.

Embodiment 2

The embodiment provides an optical interlacing filtering method for implementing a polarization multiplexing function, which can be used in a polarization multiplexing system. The method can filter the input optical signal by using the apparatus given in the first embodiment, and the specific method includes The following steps:

As shown in FIG. 3, when the optical signal 28 having the X polarization state or the optical signal 29 having the Υ polarization state is polarized After 21, after multiplexing in the polarization multiplexer 21 (arrow A in Fig. 3 indicates the polarization direction of the optical signal of the odd-wave channel, and arrow B indicates the polarization direction of the optical signal of the even-wave channel), the output terminal 211 outputs The optical circulator 22 is input to the polarization maintaining fiber 23 via the first port A1 and the second port A2 of the optical circulator 22, and is respectively written on the Bragg gratings 24 and 241 on the fast and slow axes of the polarization maintaining fiber 23. After being reflected and filtered, the X-polarized light signal or the Y-polarized light signal is output through the third port A3 of the optical circulator 22 (the output optical signal is shown as 210 in FIG. 3, and the arrow C indicates the output optical signal. The polarization direction) achieves interleaved filtering of optical signals of different polarization directions.

In the method of the embodiment, the polarization maintaining and interleaving filtering of the optical signals of different polarization directions can be realized with fewer devices, and the cost of the optical multiplexing signal interleaving filtering by the polarization multiplexing system is reduced.

Embodiment 3

This embodiment provides another structure of the optical interlacing filtering device for realizing the polarization combining function, which can be used in a common single polarization communication system or a polarization orthogonal multiplexing system. As shown in FIG. 4, the device includes: two polarization points. Waves 310, 320, two polarization combiners 31, 32, two optical circulators 33, 34, two polarization maintaining fibers 35, 36 and a polarization maintaining fiber coupler 39; wherein, each of the polarization maintaining fibers Both are provided with Bragg gratings, in particular, Bragg gratings are written on the fast and slow axes of each polarization-maintaining fiber, and Bragg gratings written on the fast and slow axes of the polarization-maintaining fibers are respectively paired with X-polarized light signals and Y Polarized light signal reflection; in practice, the frequency difference of the center frequency of the reflection spectrum of the fast and slow on-axis Bragg grating of each polarization-maintaining fiber is matched with the frequency difference of adjacent odd and even channels in the applied communication system. ;

In the above device, each polarization splitter is provided with an input terminal 37 and two output terminals; wherein the two output ends of the first polarization splitter 310 and the X polarization of the first polarization combiner 31, respectively The directional input end is connected to the Y polarization direction input end of the second polarization multiplexer 32, and is configured to divide the optical signal 40 of the odd wave channel into an X polarization state light signal and a Y polarization state light signal, and output the first to the first Two polarization combiners 31, 32;

The two output ends of the second polarization combiner 320 are respectively connected to the Y polarization direction input end of the first polarization combiner 31 and the X polarization direction input end of the second polarization combiner 32 for using the even wave channel The optical signal 41 is divided into an X-polarized light signal and a Y-polarized light signal, and output to the first and second polarization combiners 31, 32, respectively;

Each of the polarization combiners is provided with an X polarization direction input end, a Υ polarization direction input end and an output end; the output ends of the two polarization combiners 31, 32 are respectively connected to the two optical circulators 33, 34; The polarization multiplexer is configured to combine the X polarization state light signal and the Υ polarization state light signal input from the X polarization direction input end and the Υ polarization direction input end, and output the same to the connected optical circulator;

The two polarization maintaining optical fibers 35, 36 are respectively connected to the two optical circulators 33, 34; each polarization maintaining optical fiber is used for receiving a combined multiplexer output of a polarization combiner output via the connected optical circulator a signal, the received optical signal is reflected and filtered by the Bragg grating on the polarization maintaining fiber to complete optical interlacing filtering, and the filtered optical signal is output to the polarization maintaining through an output port of the connected optical circulator Fiber coupler 39;

The output ports of the two optical circulators 33, 34 are respectively connected to the polarization maintaining fiber coupler 39 as an output terminal of the optical interleaving filtering device.

The optical interleave filtering device of the embodiment can realize optical interlace filtering for a common single polarization communication system or a polarization orthogonal multiplexing system with fewer devices, and effectively reduce the single polarization communication system or the polarization orthogonal multiplexing system. The cost of optical interlacing filtering.

Embodiment 4

The embodiment provides an optical interlacing filtering method for realizing the polarization combining function, and mainly uses the optical interleaving filtering device for implementing the polarization combining function given in the third embodiment, in the ordinary single polarization communication system or the polarization orthogonal multiplexing system. The interleaving filtering of the optical signal includes:

The optical signal of the odd wave channel is divided into an X polarization state light signal and a Υ polarization state light signal by a first polarization splitter; the optical signal of the even wave channel is divided into an X polarization state light signal and a Υ polarization by the second polarization splitter State light signal

Inputting the separated X-polarized light signal of the odd-wave channel and the Υ-polarized optical signal of the even-wave channel to the first polarization combiner for combining and outputting to the first optical circulator;

The optical signal output after the multiplexed wave is input to the first polarization maintaining fiber provided with the Bragg grating via the first optical circulator, and the input optical signal is reflected by the Bragg grating on the first polarization maintaining fiber. And filtering to complete optical interleaving filtering of the optical signal;

A method for filtering in a single polarization communication system using the apparatus in the third embodiment will be described below with reference to FIG. 4:

As shown in FIG. 4, the odd and even wave channels 40, 41 (the arrow A in FIG. 4 indicates the polarization direction of the optical signal of the odd wave channel, and the arrow B indicates the polarization direction of the optical signal of the even channel) is a single polarized light signal. The odd wave channel only contains the optical signal in the X polarization direction, and the even wave channel only contains the optical signal in the Y polarization direction.

The two polarization splitters 310 and 320 are used to separate the optical signals of the odd-wave and even-wave channels 40, 41 orthogonal to the polarization state into an X-polarized light signal and a Y-polarized-state optical signal, that is, the polarization splitter 310 will The optical signal of the odd wave channel 40 is divided into an X polarization state light signal and a Y polarization state light signal, and the polarization beam splitter 320 divides the optical signal of the even wave channel 41 into an X polarization state light signal and a Y polarization state light signal;

The X-polarized light signal of the odd-wave channel 40 separated by the polarization beam splitter 310 and the Y-polarized light signal of the even-wave channel 41 separated by the polarization beam splitter 320 are respectively input to the polarization combiner 31 for combining. The optical signal after the wave is output to the polarization maintaining fiber 35 via the first port B1 and the second port B2 of the optical circulator 33, such that the optical signal in the X polarization direction of the odd wave channel 40 and the Y polarization direction of the even channel 41 The upper optical signals are respectively reflected and filtered by the Bragg gratings 351, 352 written on the fast and slow axes of the polarization maintaining fiber 35, and the X-polarized optical signals of the odd-wave channel 40 and the Y-polarized optical signals of the even-wave channel 41 And outputted through the third port B3 of the optical circulator 33 (the output optical signal is as shown by 42 in FIG. 4);

In the same principle, the Y-polarized light signal of the odd-wave channel 40 separated by the polarization beam splitter 310 and the X-polarized light signal of the even-wave channel 41 separated by the polarization beam splitter 320 enter the polarization combiner 32. After merging, the first port C1 and the second port C2 of the optical circulator 34 enter the polarization maintaining fiber 36, and the Y-polarized optical signal of the odd-wave channel and the X-polarized optical signal of the even-wave channel are written respectively. After the Bragg gratings 361, 362 on the fast and slow axes of the bias fiber 36 are reflected and filtered, the Y-polarized light signal of the odd-wave channel 40 and the X-polarized light signal of the even-wave channel 41 pass through the third of the optical circulator 34. Port C3 output;

The third ports B3, C3 of the two optical circulators 33, 34 are respectively connected to the two input terminals of the polarization maintaining fiber coupler 39, and the filtered optical signal is output through the output end of the polarization maintaining fiber coupler 39.

In the above apparatus, by adjusting the refractive index difference Δη of the fast and slow axes of the polarization-maintaining fibers 35, 36 on which the Bragg gratings 351 and 361 are written, the reflection spectrum of the Bragg grating on the fast and slow axes of the two polarization-maintaining fibers can be adjusted. The frequency interval can be used to achieve interlaced filtering of the odd and even channel optical signals. The optically interleaved filtered signal is shown as 44 in FIG. 4 (arrow C in FIG. 4 indicates the polarization direction of the filtered optical signal) .

A method for filtering in a polarization orthogonal multiplexing system using the apparatus given in the third embodiment will be described below with reference to FIG.

As shown in FIG. 5, the odd and even wave channels 50, 51 (the arrow Α in FIG. 5 indicates the polarization direction of the optical signal of the odd wave channel, and the arrow B indicates the polarization direction of the optical signal of the even wave channel) are polarization orthogonal lights. The signal, wherein the odd wave channel includes an optical signal in the X, Y polarization direction, and the even wave channel also includes an optical signal in the X, Y polarization direction.

The two polarization splitters 310 and 320 are used to separate the optical signals of the odd-wave and even-wave channels 50, 51 orthogonal to the polarization state into an X-polarized light signal and a Y-polarized-state optical signal, that is, the polarization splitter 310 will The optical signal of the odd wave channel 40 is divided into an X polarization state light signal and a Y polarization state light signal, and the polarization beam splitter 320 divides the optical signal of the even wave channel 41 into an X polarization state light signal and a Y polarization state light signal;

The X-polarized light signal of the odd-wave channel 40 separated by the polarization beam splitter 310 and the Y-polarized light signal of the even-wave channel 41 separated by the polarization beam splitter 320 are respectively input to the polarization combiner 31 for combining. The optical signal after the wave is output to the polarization maintaining fiber 35 via the first port B1 and the second port B2 of the optical circulator 33, such that the X-polarized optical signal of the odd-wave channel 50 and the Y-polarized optical signal of the even-wave channel 51 After being reflected and filtered by the Bragg gratings 351 and 352 respectively written on the fast and slow axes of the polarization maintaining fiber 35, the odd The X-polarized light signal of the wave channel 50 and the Y-polarized light signal of the even-wave channel 51 are again output through the third port Β3 of the optical circulator 33 (the output optical signal is as shown by 52 in FIG. 5);

In the same principle, the Υ-polarized light signal of the odd-wave channel 50 separated by the polarization beam splitter 310 and the X-polarized light signal of the even-wave channel 51 separated by the polarization beam splitter 320 enter the polarization combiner 32. After the wave, the first port C1 and the second port C2 of the optical circulator 34 enter the polarization maintaining fiber 36, and the Y polarization optical signal of the odd wave channel 50 and the X polarization optical signal of the even channel 51 are written respectively. After the Bragg gratings 361, 362 on the fast and slow axes of the polarization-maintaining fiber 36 are reflected and filtered, the Y-polarized light signal of the odd-wave channel 50 and the X-polarized light signal of the even-wave channel 51 pass through the optical circulator 34. Three port C3 output;

The third ports B3, C3 of the two optical circulators 33, 34 are respectively connected to the two input ends of the polarization maintaining fiber coupler, and the output of the polarization-maintaining fiber coupler 39 outputs the filtered optical signal (output The optical signal is shown as 53 in Figure 5).

In the above apparatus, by adjusting the refractive index difference Δη of the fast and slow axes of the polarization-maintaining fibers 35, 36 on which the Bragg gratings 351 and 361 are written, the reflection spectrum of the Bragg grating on the fast and slow axes of the two polarization-maintaining fibers can be adjusted. The frequency interval, so that the interlaced filtering of the odd and even channel optical signals can be realized, and the optically interleaved filtered signal is as shown by 54 in FIG. 5 (the arrow C in FIG. 5 indicates the polarization direction of the filtered output optical signal). .

In summary, in the embodiment of the present invention, the polarization multiplexer is matched with the polarization maintaining fiber written with the Bragg grating through the optical looper, and the refractive index difference between the fast and slow axes is adjusted by selecting the Bragg grating on the polarization maintaining fiber. η, at the same time realizes the functions of the polarization maintaining multiplexed wave and the optical interlacing comb filter. Due to the maturity of the Bragg grating technology, the polarization combiner is also very cheap, making the device low cost and can be controlled to less than $1,000, which is much lower than the current optical interleaving filter. The device has a simple structure and can simultaneously realize the functions of a polarization orthogonal multiplexed wave and an optical interlace filter. The nonlinear accommodation capacity of the TOM (Wave eng th Di vi s i on Mu l t p l ex ing , wavelength division multiplexing) system can be improved.

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 is within the technical scope of the present disclosure. Variations or substitutions that are readily conceivable are intended to be covered by the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

Rights request

An optical interlacing filter device for implementing a polarization multiplexing function, comprising: a polarization combiner, an optical circulator, and a polarization maintaining fiber; wherein the polarization maintaining fiber is provided with a Bragg grating;

The polarization combiner is provided with an X polarization direction input end, a Y polarization direction input end and an output end, and an output end of the polarization combiner is connected to the optical circulator for using an X or Y polarization state Outputting the output to the optical circulator;

2. The optical interlace filtering device for implementing a polarization multiplexing function according to claim 1, wherein the polarization maintaining fiber is provided with a Bragg grating comprising:

A Bragg grating is written on both the fast and slow axes of the polarization maintaining fiber, and the Bragg grating written on the fast and slow axes of the polarization maintaining fiber respectively reflects the optical signals of the X polarization state and the Y polarization state.

3. The optical interlace filtering device for implementing a polarization multiplexing function according to claim 2, wherein said writing a Bragg grating on both the fast and slow axes of said polarization maintaining fiber comprises:

The frequency difference of the center frequency of the reflection spectrum of the Bragg grating on the fast and slow axes of the polarization-maintaining fiber matches the frequency difference of the adjacent odd and even channel in the applied communication system.

4. The optical interlace filtering device for realizing polarization multiplexing function according to claim 1, wherein the polarization maintaining fiber is a polarization maintaining fiber capable of finely adjusting a refractive index difference ln between a fast axis and a slow axis by applying an external stress. optical fiber.

The optical interleaving filtering device for realizing a polarization combining function according to claim 1, wherein the optical circulator is an optical circulator having a polarization maintaining function.

6. An optical interlace filtering method for implementing a polarization combining function, comprising: Transmitting an optical signal having an X or Y polarization state from an X polarization direction input end or a Y polarization direction input end of the polarization combiner to the polarization combiner for multiplexing;

7. The optical interlace filtering method for implementing a polarization multiplexing function according to claim 6, wherein the reflecting and filtering the input optical signal by the Bragg grating fast on the polarization maintaining fiber comprises:

The input X-ray or Υ-polarized optical signal is reflected and filtered by a Bragg grating written on the fast axis and the slow axis of the polarization maintaining fiber to complete optical interleaving filtering of the X or Υ polarization optical signal.

8. An optical interlace filtering device for implementing polarization multiplexing function, comprising: two polarization splitters, two polarization combiners, two optical circulators, two polarization maintaining fibers, and a polarization maintaining a fiber coupler; wherein each of the polarization maintaining fibers is provided with a Bragg grating;

Each polarization splitter has an input end and two output ends;

Wherein the two output ends of the first polarization splitter are respectively connected to the X polarization direction input end of the first polarization combiner and the Υ polarization direction input end of the second polarization combiner for the light of the odd wave channel The signal is divided into an X-polarized light signal and a Υ-polarized light signal, and output to the first and second polarization combiners, respectively;

The two output ends of the second polarization combiner are respectively connected with the Υ polarization direction input end of the first polarization multiplexer and the X polarization direction input end of the second polarization multiplexer, and are used for dividing the optical signal of the even wave channel into An X-polarized light signal and a Υ-polarized light signal are respectively output to the first and second polarization combiners;

Each polarization multiplexer is provided with an X polarization direction input end, a Υ polarization direction input end and an output end; the output ends of the two polarization combiners are respectively connected to two optical circulators; each polarization multiplexer is used for The X-polarized light signal and the Υ-polarized light signal input from the X-polarization direction input end and the Υ-polarization direction input end are combined and output to the connected optical circulator; The two polarization maintaining optical fibers are respectively connected to the two optical circulators; each polarization maintaining optical fiber is configured to receive a combined optical signal outputted by a polarization combiner through the connected optical circulator, and the polarization maintaining The Bragg grating on the optical fiber reflects and filters the received optical signal to complete optical interlaced filtering, and the filtered optical signal is output to the polarization maintaining fiber coupler through an output port of the connected optical circulator;

9. The optical interlace filtering device for implementing polarization multiplexing function according to claim 8, wherein each of the polarization maintaining fibers is provided with a Bragg grating comprising:

A Bragg grating is written on both the fast and slow axes of each polarization maintaining fiber, and the Bragg grating written on the fast and slow axes of the polarization maintaining fiber is respectively reflected by the X polarization state light signal and the Y polarization state light signal.

10. The optical interlace filtering device for realizing polarization combining function according to claim 9, wherein said writing a Bragg grating on both the fast and slow axes of each polarization maintaining fiber comprises:

The frequency difference of the center frequency of the reflection spectrum of the Bragg grating on the fast and slow axes of each polarization maintaining fiber matches the frequency difference of adjacent odd and even channels in the applied communication system.

11. The optical interlace filtering device for realizing polarization multiplexing function according to claim 8, wherein the polarization maintaining fiber is a polarization maintaining fiber capable of finely adjusting a refractive index difference ln between a fast axis and a slow axis by applying an external stress. optical fiber.

The optical interleave filtering device for realizing a polarization combining function according to claim 8, wherein the optical circulator is an optical circulator having a polarization maintaining function.

An optical interlace filtering method for implementing a polarization multiplexing function, comprising: dividing an optical signal of a odd wave channel into an X polarization state light signal and a Y polarization state light signal by using a first polarization splitter; The optical signal of the even wave channel is divided into an X polarization state light signal and a Y polarization state light signal by a second polarization splitter;

The optical signal output after merging is input to the first protection provided with the Bragg grating via the first optical circulator a bias fiber, wherein the input optical signal is reflected and filtered by a Bragg grating on the first polarization maintaining fiber to complete optical interleaving filtering of the optical signal;

14. The optical interlace filtering method for implementing a polarization multiplexing function according to claim 13, wherein the optical signal of the odd wave channel and the optical signal of the even channel are both single polarized optical signals; or The optical signal of the odd wave channel and the optical signal of the even wave channel are both polarization state orthogonal optical signals.