CN116318415A

CN116318415A - Dense optical fiber coding method based on optical switch and weak reflectivity grating string

Info

Publication number: CN116318415A
Application number: CN202211095867.0A
Authority: CN
Inventors: 潘祯; 刘康; 彭琳钰; 刘育瑞; 汤玮; 石际; 任贞; 贺寅智
Original assignee: Guizhou Power Grid Co Ltd
Current assignee: Guizhou Power Grid Co Ltd
Priority date: 2022-09-08
Filing date: 2022-09-08
Publication date: 2023-06-23

Abstract

The invention discloses a dense optical fiber coding method based on an optical switch and a weak reflectivity grating string, which comprises the following steps: step 1, a light source module emits a C-band pulse signal, wherein the signal comprises light pulses with different central wavelengths and overlapping time domains; step 2, coding each node by utilizing a weak reflectivity grating string to obtain pulse combination types with different wavelengths, wherein coded signals of different coding nodes on the same link are different in time domain interval; step 3, the coded signals are injected into the arrayed waveguide grating through the optical circulator and are decomposed into more than one pulse signal with single wavelength; step 4, carrying out photoelectric conversion on the coded pulse signals by adopting a detector array and an acquisition card, and outputting the acquired signals to an FPGA and an upper computer for processing and displaying; the method solves the problem that the prior art cannot be suitable for realizing real-time coding of a large-scale high-reliability all-optical network; the limited real-time coding scale can not meet the use requirement of a large-scale network.

Description

Dense optical fiber coding method based on optical switch and weak reflectivity grating string

Technical Field

The invention belongs to the technical field of optical fiber coding, and particularly relates to a dense optical fiber coding method based on an optical switch and a weak reflectivity grating string.

Background

Optical fiber coding is the basic and core technology for realizing all-optical network digitization. The optical fiber link safety is the basis for ensuring the optical access network safety, and researches show that about one third of the optical network faults are caused by the optical fiber cable faults, so that each optical fiber link in the optical access network is digitally encoded, and the network state is monitored by utilizing the encoding, so that the more accurate, reliable, intelligent and efficient all-optical network digital management is the premise that the optical access network can operate efficiently and stably. The optical fiber coding efficiency directly influences the effect of realizing the full optical network digitization, the dense optical fiber coding method based on the optical switch and the weak reflectivity grating string can finish coding more links by using fewer wavelength resources, saves spectrum resources, and can greatly improve the scale of the full optical network digitization technology monitorable network when the optical fiber channel is tense and the number of users is gradually increased.

Most of the currently used optical fiber coding techniques only use fiber gratings to perform one-dimensional or two-dimensional wavelength coding on monitoring light pulses. The one-dimensional code wavelength code can only distribute a single wavelength as a unique label for one link, has the advantages of simple structure and convenient realization, the encoder only comprises one fiber grating arranged at the user end, and the defect is obvious that the used spectrum resource linearly grows along with the number of the code links, and can only meet the code requirement of a small-scale optical network. The two-dimensional wavelength coding uses an optical encoder consisting of a fiber grating and a one-to-two optical splitter, the encoder is arranged at a local side in an access network, the complexity of a user side is reduced by adopting centralized coding, the coding efficiency is greatly improved compared with one-dimensional coding, but the coding efficiency is limited by spectrum resources in practical use and still only can realize the coding of hundreds of links.

The method for increasing the number of codes is mainly multiplexing in time domain, dividing a plurality of users into a group, adopting a polling mode, only coding the optical fiber links of a certain group of users in a period of time, and effectively coding each optical fiber link by setting a proper polling period. The effective coding quantity increase can be realized by simply using an optical switching and control circuit in combination with the time division multiplexing wavelength coding method, but when the monitoring link is longer, the polling window allocated to each group of users also needs to be correspondingly increased, and in addition, the increase of the quantity of users also needs to poll more groups to meet the demands, so that the polling period is inevitably prolonged, the time for the users to be not identified and managed is increased, and the response efficiency of fault monitoring is reduced.

The aimed coding technique is not suitable for realizing the real-time coding of the large-scale and high-reliability all-optical network

Disclosure of Invention

The invention aims to solve the technical problems that: the dense optical fiber coding method based on the optical switch and the weak reflectivity grating string is provided to solve the problem that the prior art cannot be suitable for realizing real-time coding of a large-scale high-reliability all-optical network; the technical scheme of the invention is as follows:

the invention has the beneficial effects that:

the invention takes the multi-wavelength detection light pulse synchronously output by the multi-wavelength pulse light source as the carrier of coding information, and codes the pulse wavelength by the light switch and the weak reflectivity fiber bragg grating, thus realizing the coding of a large number of users under the condition of using limited wavelength resources. The light source module emits C-band pulse signals, the signals comprise a plurality of optical pulses with different central wavelengths and overlapping in time domain, then the optical pulses enter different optical links through a branching device, a series of fiber gratings with weak reflectivity are placed on each link through one optical node, the pulse wavelengths are selectively reflected to form a unique pulse wavelength combination of the optical node, other unreflected pulse light and the pulse light remained after reflection continue to encode the next optical node, and for a certain link, the optical pulses entering each optical node are separated in wavelength domain wavelength combination type and each wavelength in time domain to jointly form unique code information.

The method solves the problem that the prior art cannot be suitable for realizing real-time coding of a large-scale high-reliability all-optical network; the limited real-time coding scale can not meet the use requirement of a large-scale network.

Drawings

FIG. 1 is a general block diagram of coded light pulses from generation into a fiber link and a receiving module;

FIG. 2 is a spectrum of an optical pulse output by a multi-wavelength laser;

FIG. 3 is a block diagram of a weak reflectivity fiber grating string encoder;

FIG. 4 is a graph of the spectrum of light pulses passing through a train of weak reflectivity gratings;

fig. 5 is a graph of the intensity of the light pulses of the encoded signal output by the weak reflectivity grating serial encoder.

Detailed Description

In order to improve the optical nodes which can be coded simultaneously on one optical fiber link, the invention provides the following coding method: the method comprises the following steps:

(1) C-band pulse signals are emitted by a multi-wavelength pulse light source in the light source module, wherein the signals comprise more than 6 optical pulses with different central wavelengths and overlapping in time domain;

(2) And coding each node by using the weak reflectivity grating string to obtain reflected pulse signals of different wavelength pulse combination types, wherein the coded signals of different coding nodes on the same link are different in time domain interval.

(3) The reflected pulse signals are injected into the arrayed waveguide grating through the optical circulator and are decomposed into a plurality of pulse signals with single wavelength.

(4) The coded pulse signals are subjected to photoelectric conversion by adopting a detector array and a 6-port acquisition card, and the acquired signals are output to an FPGA and an upper computer for processing and display.

The multi-wavelength pulse light source in the scheme can be controlled by an external signal, and more than 6 laser arrays can generate the same width, power and period in the time domain; the optical pulses with different central wavelengths and the same 3dB bandwidth in the wavelength domain, the interval between the central wavelengths of adjacent optical pulses is larger than the bandwidth of the adjacent optical pulses so as to ensure that the pulses are not aliased in the wavelength domain, and the pulses leave the laser at the same time and are combined into one pulse in the time domain through a coupler built in the light source module.

The weak-reflectivity grating strings in the scheme are formed by connecting a plurality of weak-reflectivity grating strings in series, and each grating string at least comprises one weak-reflectivity grating in order to ensure that each coding node comprises an optical pulse signal with at least one wavelength; to ensure that the optical pulse signal is sufficiently powered through all of the encoded nodes, the reflectivity of the weak reflectivity grating is sufficiently low (1% and below), reflecting a portion and transmitting a portion of the optical pulse signal.

According to the multi-port acquisition card and the detector array in the scheme, the light source signals containing multiple wavelengths in the time domain can be separated in the wavelength domain through the array waveguide grating, so that the signals received by each port only contain one wavelength and are uploaded to the PC end through the FPGA.

In the above scheme, in order to make each coded signal contain at least one wavelength pulse signal, a total of 2 can be generated by using optical pulses containing n wavelengths on one optical link ⁿ -1 codes, each code may uniquely correspond to a code node in a fiber optic link.

Fig. 1 is a general block diagram of coded light pulses from generation into a fiber link and a receiving module. The light source module emits C-band pulse signals, the signals comprise more than 6 optical pulses with different central wavelengths and overlapping in time domain, then the optical pulse signals are selectively reflected back at each coding node formed by the weak reflection gratings, the reflected pulse signals enter the receiving module through the optical circulator, and the reflected pulse signals are uploaded to the upper computer through the FPGA to be subjected to signal processing to obtain unique codes of each coding node.

FIG. 2 is a spectrum of an optical pulse output by a multi-wavelength laser. An optical pulse is formed by combining a plurality of pulses with different center wavelengths, and the distances between adjacent center wavelengths are the same.

Fig. 3 is a diagram of a structure of a weak reflectivity fiber grating serial encoder. The grating strings are formed by connecting a plurality of weak-reflectivity grating strings in series, and each grating string at least comprises one weak-reflectivity grating in order to ensure that each coding node comprises at least one optical pulse signal with wavelength; in order to ensure that the power of the optical pulse signal passing through all the encoding nodes is sufficient, the reflectivity of the weak reflectivity grating is low enough to reflect a part of the optical pulse signal and transmit a part of the optical pulse signal; in order to make each coded signal contain pulses of at least one wavelength, a total of 2 can be generated on an optical link using optical pulses containing n wavelengths ⁿ -1 codes, each code may uniquely correspond to a code node in a fiber optic link.

FIG. 4 is a graph of the spectrum of the encoded signal light pulses output by the weak reflectivity grating serial encoder. In which several selected wavelengths (lambda ₁ ，λ ₂ ，λ ₃ ，λ ₄ ) Three encoded signals within the range, each encoded wavelength being (lambda) ₁ ，λ ₂ )、(λ ₁ ，λ ₃ ，λ ₄ )、(λ ₁ ，λ ₂ ，λ ₃ ) Each encoded signal is separated in the time domain and contains a different wavelength.

Fig. 5 is a graph of the intensity of the light pulses of the encoded signal output by the weak reflectivity grating serial encoder. For a light pulse of a particular wavelength, the transmitted light pulse signal power decays a portion after each pass through a grating train containing that wavelength. Taking reflectance of 5% as an example, for wavelength lambda ₁ The reflected and transmitted signal intensities of the optical pulse signals of (a) are shown.

The embodiment of the invention discloses a specific implementation flow of a dense optical fiber coding method based on an optical switch and a fiber grating with weak reflectivity, and the number of optical wavelengths used in the method can be adjusted according to actual conditions.

Claims

1. An intensive optical fiber coding method based on an optical switch and a weak reflectivity grating string is characterized in that: the method comprises the following steps:

step 1, a light source module emits a C-band pulse signal, wherein the signal comprises light pulses with different central wavelengths and overlapping time domains;

step 2, coding each node by utilizing a weak reflectivity grating string to obtain pulse combination types with different wavelengths, wherein coded signals of different coding nodes on the same link are different in time domain interval;

step 3, the coded signals are injected into the arrayed waveguide grating through the optical circulator and are decomposed into more than one pulse signal with single wavelength;

and 4, carrying out photoelectric conversion on the coded pulse signals by adopting a detector array and an acquisition card, and outputting the acquired signals to an FPGA and an upper computer for processing and displaying.

2. The method for dense optical fiber coding based on optical switches and weak reflectivity grating strings of claim 1, wherein: the light source module is a multi-wavelength pulse light source and is controlled by external signals, and at the same time, the total laser array generates more than one light pulse with the same width, power and period in the time domain, different central wavelengths in the wavelength domain and the same 3dB bandwidth.

3. The method for dense optical fiber coding based on optical switches and weak reflectivity grating strings of claim 2, wherein: the interval between the central wavelengths of adjacent light pulses is larger than the bandwidth, and each pulse simultaneously leaves the laser and is combined into one pulse in the time domain through a coupler built into the light source module.

4. The method for dense optical fiber coding based on optical switches and weak reflectivity grating strings of claim 1, wherein: the weak reflectivity grating string is formed by serially connecting a plurality of weak reflectivity grating strings.

5. The method for dense optical fiber coding based on optical switches and weak reflectivity grating strings of claim 4, wherein: each weak reflectivity grating string comprises at least one weak reflectivity grating; the reflectivity of the weak reflectivity grating is not higher than 1%.

6. The method for dense optical fiber coding based on optical switches and weak reflectivity grating strings of claim 1, wherein: the acquisition card is a multi-port acquisition card, the multi-port acquisition card and the detector array divide light source signals containing multiple wavelengths in the time domain in the wavelength domain through the array waveguide grating, so that the signals received by each port only contain one wavelength and are uploaded to the PC end through the FPGA high-speed acquisition card.

7. The method for dense optical fiber coding based on optical switches and weak reflectivity grating strings of claim 1, wherein: each encoded signal contains pulses of at least one wavelength, and a total of 2 are generated on an optical link using optical pulses containing n wavelengths ⁿ -1 codes, each code uniquely corresponding to one code node in one fiber optic link.

8. The method for dense optical fiber coding based on optical switches and weak reflectivity grating strings of claim 1, wherein: an optical pulse is composed of more than one pulse with different central wavelengths, and the intervals between adjacent central wavelengths are same, so that the main frequency components of each wavelength are not overlapped.