CN210297707U

CN210297707U - Two-dimensional incoherent OCDMA system

Info

Publication number: CN210297707U
Application number: CN201921292166.XU
Authority: CN
Inventors: 王晓玲; 张国东
Original assignee: Suzhou University
Current assignee: Suzhou University
Priority date: 2019-08-09
Filing date: 2019-08-09
Publication date: 2020-04-10
Anticipated expiration: 2029-08-09

Abstract

The utility model discloses a two-dimentional incoherent OCDMA system, include: the device comprises at least one two-dimensional encoder, a coupler, at least one two-dimensional decoder, at least one optical hard limiter, at least one photoelectric detector and at least one threshold device, wherein the two-dimensional encoder is connected with the coupler, the coupler is connected with the two-dimensional decoder, and the two-dimensional decoder is sequentially connected with the optical hard limiter, the photoelectric detector and the filter one by one. The two-dimensional encoder includes: the optical fiber Bragg grating encoder is connected with the optical fiber delay line encoder. The two-dimensional decoder includes: the optical fiber delay line decoder is connected with the optical fiber Bragg grating decoder. By connecting the optical hard limiter between the two-dimensional decoder and the photoelectric detector, the multi-user interference can be effectively reduced, and the performance of the system is improved.

Description

Two-dimensional incoherent OCDMA system

Technical Field

The utility model relates to an optical fiber communication field especially relates to a two-dimentional incoherent OCDMA system.

Background

With the increasing demand for quality of life, the internet has become closely related to human life. Because of the convenience, high efficiency and universality of the Internet, people can get in touch with the Internet in various aspects of entertainment, work and study in life, even business, medical treatment, transportation and the like. With this rapid growth in society, traditional inefficient communication networks have been unable to meet the demand. In this case, the whole society will be in a state of great difficulty without a new and efficient network support. To solve this dilemma, it is therefore necessary to establish a more efficient network. The former communication network mostly uses copper wire transmission and reaches the electronic bottleneck, so another transmission medium with better performance is used for realizing the construction work of the high-speed communication network. The emergence of optical fibers solves the problem, and the future use of optical fibers to completely replace copper wire transmission is a necessary trend.

Optical Code Division Multiple Access (OCDMA) has the advantages of high security, high bandwidth utilization rate, random Access and the like, not only solves the problem of insufficient bandwidth, but also improves the security and safety of transmitted information. However, its multi-user interference is large.

In view of the foregoing, it is desirable to provide a two-dimensional non-coherent OCDMA system that reduces multi-user interference.

SUMMERY OF THE UTILITY MODEL

For solving the above problem, the utility model provides a two-dimentional incoherent OCDMA system, include: the device comprises at least one two-dimensional encoder, a coupler, at least one two-dimensional decoder, at least one optical hard limiter, at least one photoelectric detector and at least one threshold device, wherein the two-dimensional encoder is connected with the coupler, the coupler is connected with the two-dimensional decoder, and the two-dimensional decoder is sequentially connected with the optical hard limiter, the photoelectric detector and the filter one by one.

Preferably, the two-dimensional encoder includes: the optical fiber Bragg grating encoder is connected with the optical fiber delay line encoder.

Preferably, the two-dimensional decoder includes: the optical fiber delay line decoder is connected with the optical fiber Bragg grating decoder.

Preferably, the threshold device comprises a low pass filter.

Preferably, the coupler comprises a star coupler.

Preferably, the device further comprises at least one light modulator, and the light modulator is connected with the two-dimensional encoder.

Preferably, the system further comprises at least one laser, and the laser is connected with the optical modulator.

Preferably, the system further comprises at least one receiver, wherein the receiver is connected with the filter.

The utility model has the advantages that: by connecting the optical hard limiter between the two-dimensional decoder and the photoelectric detector, multi-user interference can be effectively reduced.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to denote like parts throughout the drawings. In the drawings:

fig. 1 is a schematic diagram of a two-dimensional incoherent OCDMA system provided by the present invention;

fig. 2 is a schematic diagram of a transmitting end of a two-dimensional incoherent OCDMA system in an emulation system;

fig. 3 is a schematic diagram of a receiving end of a two-dimensional incoherent OCDMA system in an emulation system according to the present invention;

fig. 4 is a user signal diagram of a two-dimensional incoherent OCDMA system provided by the present invention;

fig. 5 is a signal diagram of a transmitting end of a two-dimensional incoherent OCDMA system provided by the present invention;

fig. 6 is a signal diagram of a receiving end of a two-dimensional incoherent OCDMA system provided by the present invention;

fig. 7 is an eye diagram of a two-dimensional incoherent OCDMA system provided by the present invention.

Detailed Description

Exemplary embodiments of the present invention will be further described with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in fig. 1, the utility model discloses a two-dimensional incoherent OCDMA system, include: the device comprises at least one two-dimensional encoder, a coupler, at least one two-dimensional decoder, at least one optical hard limiter, at least one photoelectric detector and at least one threshold device, wherein the two-dimensional encoder is connected with the coupler, the coupler is connected with the two-dimensional decoder, and the two-dimensional decoder is sequentially connected with the optical hard limiter, the photoelectric detector and the filter one by one.

The two-dimensional encoder includes: the Fiber Bragg Grating encoder is connected with the Fiber delay line encoder.

In the two-dimensional encoder, signals pass through a fiber Bragg grating encoder and then pass through a fiber delay line encoder.

The two-dimensional decoder includes: the optical fiber delay line decoder is connected with the optical fiber Bragg grating decoder.

In the two-dimensional decoder, the signal passes through an optical fiber delay line decoder and then an optical fiber Bragg grating decoder.

The threshold device comprises a filter, which may preferably be a low pass filter.

The coupler comprises a star coupler.

Preferably, the embodiment of the present application further comprises at least one light modulator, which is connected to the two-dimensional encoder.

Preferably, embodiments of the present application further comprise at least one laser, said laser being connected to said light modulator.

Preferably, the embodiment of the present application further comprises at least one receiver, said receiver being connected to said filter.

Fig. 2 is a schematic diagram of a transmitting end in a simulation system. The transmitting end consists of a user sequence generator, a non-return-to-zero pulse generator, a white light source, a Mach-Zehnder modulator, an optical beam splitter, an FBG grating, an optical fiber delay line and an optical coupler.

Fig. 3 is a schematic diagram of the receiving end in the simulation system. The receiving end is composed of an optical beam splitter, an optical fiber delay line, an FBG grating, an optical hard limiter, an optical coupler, a PIN photoelectric detector and a low-pass filter. The user code word of the single-user system adopts an OOC code, the code length is 11, and the code weight is 3. The system transmission rate is set to 2.5Gbit/s, the user chip pulse width is 0.25ns, and the total time delay is 2.75 ns. The light source adopts a white light emitter with the wavelength of 1550nm and the signal intensity of-85 dB.

The FBG grating has a spectrum range of 1548nm to 1552nm, a reflection spectrum width of 0.2nm, and a wave plate number which is equally divided according to 11 with a tolerance of 0.4nm, namely (lambda 1, lambda 2, … …, lambda 11) is (1548nm, 1548.4nm, 1549.2nm, … …, 1551.6nm, 1552 nm).

At the transmitting end, as shown in fig. 4, for the signals of the user 1 and the user 2, after passing through the two-dimensional encoders controlled by respective address codes, frequency domain encoded signals and time domain encoded signals of the user 1 and the user 2 as shown in (a), (b), (c) and (d) of fig. 5 are generated, and then after passing through the 2 × 1 optical coupler, mixed encoded signals as shown in (e) and (f) of fig. 5 are formed. The mixed coded signal passes through the decoders of user 1 and user 2 at the receiving end, and forms a decoded signal as shown in fig. 6(a), (b), (c) and (d), and it can be seen that there is a small interference signal in the decoded signal of user 2. And then outputs two groups of signals shown in fig. 6(e) and (f) after passing through the optical hard limiter, the photoelectric detector and the low-pass filter, and the output signals of the two users are consistent with the input signals. The two diagrams shown in fig. 7(a) and (b) are eye diagrams of the user 1 and the user 2, respectively, the opening angle of the two eye diagrams is relatively large, and the shape of the eye diagrams is relatively perfect.

As shown in table 1, is a multi-user two-dimensional time domain/frequency domain eye diagram analyzer observed value. The error rate of both users is far less than 10^-9. Without the addition of the optical hard limiter, the bit error rate for user 1 is about 10^-50And Q is 14.4931; the bit error rate of user 2 is about 10^-24The Q value is 9.49517. Compared with the situation that no optical hard limiter is added, the system performance is improved by times.

TABLE 1

The advantage of this embodiment is that by accessing the optical hard limiter between the two-dimensional decoder and the photodetector, the multi-user interference can be effectively reduced, and the performance of the system can be improved.

The above description in this specification is merely illustrative of the present invention. Those skilled in the art can make various modifications or additions to the described embodiments or substitute them in a similar manner without departing from the scope of the present invention as defined in the following claims.

Claims

1. A two-dimensional non-coherent OCDMA system, comprising: the device comprises at least one two-dimensional encoder, a coupler, at least one two-dimensional decoder, at least one optical hard limiter, at least one photoelectric detector and at least one threshold device, wherein the two-dimensional encoder is connected with the coupler, the coupler is connected with the two-dimensional decoder, and the two-dimensional decoder is sequentially connected with the optical hard limiter, the photoelectric detector and the filter one by one.

2. The system of claim 1, wherein the two-dimensional encoder comprises: the optical fiber Bragg grating encoder is connected with the optical fiber delay line encoder.

3. The system of claim 1, wherein the two-dimensional decoder comprises: the optical fiber delay line decoder is connected with the optical fiber Bragg grating decoder.

4. The system of claim 1, wherein the threshold device comprises a low pass filter.

5. The system of claim 1, wherein the coupler comprises a star coupler.

6. The system of claim 1, further comprising at least one light modulator, the light modulator coupled to the two-dimensional encoder.

7. The system of claim 6, further comprising at least one laser coupled to the optical modulator.

8. The system of claim 1, further comprising at least one receiver, said receiver being coupled to said filter.