A three-in-one wavelength division multiplexing optical time domain reflectometer system and control method thereof

Abstract

The present invention provides a three-in-one wavelength division multiplexing optical time domain reflectometer system and a control method thereof, comprising a laser emission module, an optical switching module, an optical coupling module, a three-in-one optical port optically connected in sequence, an optical detection receiving module, an amplification module, a data acquisition and analysis module connected in sequence to the optical switching module, and a control module electrically connected to the laser emission module and the data acquisition and analysis module; the laser emission module comprises a DWDM laser emission module, a CWDM laser emission module and a PON laser emission module arranged in parallel. The present invention combines a filtering method with a light source and an optical path design, and the system can provide 115 wavelengths, including 18 wavelengths of CWDM, 96 wavelengths of DWDM, and 1 wavelength of PON. These three light sources can be output through one optical fiber, avoiding the replacement of corresponding optical ports when testing different light sources, saving operation convenience, saving test time, and improving test efficiency and consistency; nanosecond switching between different channels can be achieved by using a multi-channel signal scheduling processing module.

Description

Technical Field

[0001] The present invention relates to the technical field of basic electrical components, and in particular to a three-in-one wavelength division multiplexing optical time domain reflectometer system and a control method thereof. Background Art

[0002] Wavelength division multiplexing technology is one of the transmission technologies widely used in optical network communications at home and abroad. It is of great significance to the capacity expansion, speed increase and long-distance transmission of optical communications.

[0003] Among the optical networks with various transmission standards, coarse wavelength division multiplexing (CWDM, generally used in metropolitan area networks), dense wavelength division multiplexing (DWDM, generally used in backbone networks) and passive optical network (PON, generally used for short-distance transmission) transmission technologies are currently widely used.

[0004] Wavelength division multiplexing (WDM) technology can combine and transmit different wavelengths simultaneously in the same optical fiber, thereby realizing the multiplexing transmission of multiple optical signals in one optical fiber, and ultimately expanding the transmission capacity in the same optical fiber by dozens or hundreds of times, easily realizing high-speed, broadband, ultra-large capacity, and stable information transmission functions in the optical domain.

[0005] In the future, with the advancement of current 5G technology and the development of broadband high-speed communication technology, the optical fiber communication network in the fields of international cross-sea business, radio and television, electricity, petrochemical and other special networks will continue to expand and accelerate the adoption of high-speed and large-capacity CWDM and DWDM wavelength division multiplexing technology optical fiber networks to support the growing bandwidth and rate requirements. CWDM and DWDM wavelength division multiplexing technologies have the advantages of high transmission rate, long transmission distance, good security, separate signal transmission, and easy upgrade, and are considered to be one of the most attractive solutions in optical access networks. Therefore, the number of channels using WDM systems continues to develop towards more channels, which requires the corresponding test equipment to have more measurement wavelengths to meet the needs of network development.

[0006] At present, in long-distance point-to-point optical fiber links, optical time domain reflectometers (OTDR) are commonly used as optical fiber fault detection tools, but ordinary optical time domain reflectometers can only test a few common wavelengths, such as 850nm, 1310nm, 1550nm, 1625nm, and 1650nm. The wavelength division multiplexing optical time domain reflectometers for CWDM and DWDM can only test the corresponding wavelengths of a single light source CWDM, DWDM or PON. When testing different light sources, it is necessary to replace the device or replace the test port, which cannot meet the needs of testing three light sources on one optical port, and is not convenient and fast enough for front-line maintenance personnel.

[0007] Therefore, there is a need for a long-distance point-to-point optical fiber link that takes into account the needs of multiple light sources. Summary of the invention

[0008] The present invention aims to solve the problem of long-distance point-to-point optical fiber links required by multiple light sources, and provides a three-in-one wavelength division multiplexing optical time domain reflectometer system and a control method thereof. Through the light source and optical path design combined with the filtering method, the system can provide 115 wavelengths, including 18 wavelengths of CWDM, 96 wavelengths of DWDM, and 1 wavelength of PON. These three light sources can be output through one optical fiber, avoiding the need to replace the corresponding optical port when testing different light sources, which is convenient to operate, saves test time, and improves test efficiency and consistency; nanosecond switching between different channels can be achieved by using a multi-channel signal scheduling processing module.

[0009] The present invention provides a three-in-one wavelength division multiplexing optical time domain reflectometer system, comprising a laser emission module, an optical switching module, an optical coupling module, and a three-in-one optical port optically connected in sequence, an optical detection receiving module, an amplification module, and a data acquisition and analysis module connected in sequence to the optical switching module, and a control module electrically connected to the laser emission module and the data acquisition and analysis module;

[0010] The laser emission module includes a DWDM laser emission module, a CWDM laser emission module and a PON laser emission module which are arranged in parallel, the DWDM laser emission module, the CWDM laser emission module and the PON laser emission module are all optically connected to the optical switching module, and the DWDM laser emission module, the CWDM laser emission module and the PON laser emission module are all electrically connected to the control module;

[0011] The control module drives the DWDM laser emission module, the CWDM laser emission module and the PON laser emission module to emit pulse light. The control module analyzes and judges the test data output by the data acquisition and analysis module and adjusts the emission wavelengths of the DWDM laser emission module, the CWDM laser emission module and the PON laser emission module. The optical switching module switches the channels in the process of transmitting and receiving the pulse signals of the DWDM laser emission module, the CWDM laser emission module and the PON laser emission module under the control of the control module. The optical coupling module couples the pulse signals output by the DWDM laser light source, the CWDM laser light source and the PON laser light source to the optical fiber under test through the three-in-one optical port and transmits the reflected signals and scattered signals in the optical fiber under test back to the optical detection receiving module through the three-in-one optical port and the optical switching module. The optical detection receiving module detects and collects the signals in the optical fiber under test and outputs them after photoelectric conversion. The amplification module receives the signals output by the optical detection receiving module and outputs them after conditioning and amplification. The data acquisition and analysis module receives the signals output by the amplification module and outputs them to the control module after analysis.

[0012] The three-in-one wavelength division multiplexing optical time domain reflectometer system described in the present invention, as a preferred embodiment, the optical switching module includes a first circulator optically connected to the output end of the DWDM laser transmitting module, a second circulator optically connected to the output end of the PON laser transmitting module, a first optical switch optically connected to the output end of the photoelectric detection receiving module, and a second optical switch optically connected to the optical coupling module;

[0013] The optical coupling module includes an optical coupler, a first wavelength division multiplexer and a second wavelength division multiplexer;

[0014] The first wavelength division multiplexer is optically connected to the first circulator, the second circulator and the first optical switch, the second wavelength division multiplexer is optically connected to the first circulator, the second circulator and the second optical switch, the input end of the coupler is optically connected to the first optical switch and the output end of the CWDM laser transmitter module, the input end of the second optical switch is optically connected to the optical coupler and the second wavelength division multiplexer, and the output end of the second optical switch is connected to the three-in-one optical port.

[0015] The three-in-one wavelength division multiplexing optical time domain reflectometer system described in the present invention is, as a preferred embodiment, a DWDM laser transmitting module outputs a 96-channel optical signal with a wavelength tuning range of 1528.77nm to 1566.72nm, a channel spacing of 0.4nm, and a wavelength accuracy of 0.02nm, a CWDM laser transmitting module outputs an 18-channel optical signal with a wavelength range of 1270nm to 1610nm and a channel spacing of 20nm, and the wavelength of the optical signal output by the PON laser transmitting module is 1650nm.

[0016] The three-in-one wavelength division multiplexing optical time domain reflectometer system described in the present invention, as a preferred embodiment, the DWDM laser emission module is a modulated grating Y-branch variable wavelength laser using an integrated semiconductor optical amplifier;

[0017] The CWDM laser transmitting module is a DBF laser;

[0018] The first optical switch and the second optical switch are integrated waveguide optical switches,

[0019] The data acquisition and analysis module filters the measuring points, and the data acquisition and analysis module includes a channel selection module, a data receiving module, a data processing module, a data buffer module and a result output module.

[0020] The present invention provides a control method for a three-in-one wavelength division multiplexing optical time domain reflectometer system, comprising the following steps:

[0021] S1, the control module drives the laser emission module to emit pulse light through wavelength division multiplexing and outputs it to the optical fiber under test through the optical switching module, the optical coupling module, and the three-in-one optical port. The laser emission module includes a DWDM laser emission module, a CWDM laser emission module, and a PON laser emission module arranged in parallel;

[0022] S2. Echo detection: The control module analyzes and judges the test data through the light detection receiving module, the amplification module and the data acquisition and analysis module.

[0023] The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system described in the present invention, as a preferred embodiment, step S1 includes the following steps:

[0024] S11, the control module drives the DWDM laser emission module, the CWDM laser emission module and the PON laser emission module to emit pulse light through wavelength division multiplexing and outputs it to the optical fiber under test through the three-in-one optical port, the DWDM laser emission module output enters step S12, the CWDM laser emission module output enters step S13, and the PON laser emission module output enters step S14;

[0025] S12, the control module drives the DWDM laser emission module to emit pulsed laser output to the optical switching module, which is sequentially output to the three-in-one optical port after passing through the first circulator, the second wavelength division multiplexer, and the second optical switch, and then enters step S2;

[0026] S13, the control module drives the CWDM laser emission module to emit pulsed laser output, which is output to the three-in-one optical port after passing through the optical coupler and the second optical switch in sequence, and then enters step S2;

[0027] S14, the control module drives the PON laser light source to emit pulsed laser output to the optical switching module, which is output to the three-in-one optical port after passing through the second circulator, the second wavelength division multiplexer, and the second optical switch in sequence, and then enters step S2.

[0028] The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system described in the present invention, as a preferred embodiment, step S2 includes the following steps:

[0029] S21, the control module detects and collects the pulse signal reflection and scattering signals of the DWDM laser light source, CWDM laser light source and PON laser light source in the measured link through the optical detection receiving module, and the detection signal collection of the DWDM laser light source enters step S22, the detection signal collection of the CWDM laser light source enters step S23, and the detection signal collection of the PON laser light source enters step S24;

[0030] S22, after the detection signal of the DWDM laser light source is input through the three-in-one optical port, it passes through the second optical switch, the second wavelength division multiplexer, the first circulator, the first wavelength division multiplexer, and the first optical switch in sequence, and then inputs into the optical detection receiving module, and enters step S25;

[0031] S23, after the detection signal of the CWDM laser light source is input through the three-in-one optical port, it passes through the second optical switch, the coupler, and the first optical switch in sequence and then inputs into the optical detection receiving module, and then goes to step S25;

[0032] S24, after the detection signal of the PON laser transmitting module is input through the three-in-one optical port, it passes through the second optical switch, the second wavelength division multiplexer, the second circulator, the first wavelength division multiplexer, and the first optical switch in sequence, and then inputs into the optical detection receiving module, and enters step S25;

[0033] S25, the optical detection receiving module performs photoelectric conversion on the detection signals of the DWDM laser light source, the CWDM laser light source, and the PON laser light source, and then outputs the converted signals to the amplification module, and the amplification module performs differential processing, logarithmic processing, and virtual ground processing on the detection signals, and then outputs the converted signals to the data acquisition and analysis module;

[0034] S26, the data acquisition and analysis module receives the detection signal and performs filtering and analysis processing and then outputs it to the control module. The control module compares the wavelength of the detection signal with the initially set wavelength and then fine-tunes the current so that the wavelength of the emitted laser meets the accuracy requirements.

[0035] The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system described in the present invention is, as a preferred embodiment, in step S22, the DWDM laser light source is set to have left and right grating micro-control, phase micro-control, SOA micro-control, temperature control and gain current micro-control, and the DWDM laser light source controls the output wavelength through the left and right reflectors and the phase current, and controls the output power through the gain and the semiconductor optical amplifier current;

[0036] In step S23, the CWDM laser light source controls the DBF laser to operate through the driving circuit;

[0037] In step S24, the PON laser light source sends instructions through the master control module to control the operation of the driving module;

[0038] In step S26, the data acquisition and analysis module uses a multi-channel control multiplexing structure; the channel selection module of the data acquisition and analysis module selects a signal receiving channel, and the corresponding data receiving module receives the signal data and outputs it to the data processing module for data analysis and processing. The processing process data is temporarily stored in the data cache module. After the data processing is completed, the result is output through the result output module. The channel selection module coordinates the operation of the data receiving module, the data processing module, the data cache module and the result output module.

[0039] A control method for a three-in-one wavelength division multiplexing optical time domain reflectometer system described in the present invention is, as a preferred embodiment, in step S22, the laser emission process of the DWDM laser light source is: two reflectors on one side of the laser resonant cavity have at least one reflection peak, when the laser is working, the current is injected to tune the reflector, the two reflected lights are superimposed together through a 1*2 combiner or splitter, the reflectivity of the front end is improved and a comb-shaped reflection spectrum is generated, the Bragg grating groups at both ends of the laser generate different comb-shaped reflection spectra, and when the light is reflected back and forth between the two ends of the laser, the two different reflection spectra are superimposed to obtain the required wavelength range.

[0040] The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system described in the present invention is, as a preferred embodiment, in step S26, the data acquisition and analysis module uses a filtering algorithm of five-point cubic smoothing and least squares fitting:

[0041]

[0042] Among them, y x is the pixel value of the measurement point x, is the filtered value of the measurement point x.

[0043] A three-in-one wavelength division multiplexing optical time domain reflectometer system of the present invention comprises:

[0044] Control module: The control module is responsible for driving the DWDM laser transmitting module, CWDM laser transmitting module, and PON laser transmitting module to transmit pulse light, and is responsible for analyzing and judging the test data;

[0045] Laser emission module, the laser emission module includes DWDM laser emission module, CWDM laser emission module, PON laser emission module;

[0046] Optical switching module: The optical switching module realizes channel switching during the pulse signal transmission and reception process of the DWDM laser transmitting module, CWDM laser transmitting module, and PON laser transmitting module. The control module issues instructions to control the nanosecond switching of channels for different test requirements.

[0047] Optical coupling module: The optical coupling module couples the pulse signals of the DWDM laser light source, CWDM laser light source, and PON laser light source into the link under test, and transmits the reflected and scattered signals in the link under test back to the photoelectric detection receiving module.

[0048] Optical detection receiving module, which detects and collects the pulse signal reflection and scattered signals of the DWDM laser light source, CWDM laser light source, and PON laser light source in the tested link to realize the photoelectric conversion function

[0049] An amplifier module, which conditions and amplifies the signal output by the photoelectric detection receiving module;

[0050] A data acquisition and analysis module, wherein the data acquisition and analysis module performs analysis and processing on the received signals;

[0051] Three-in-one optical port: The three-in-one optical port injects the optical pulse emitted by the coupler module into the optical fiber under test;

[0052] The DWDM laser transmitter module outputs a 96-channel optical signal with a wavelength tuning range of 1528.77nm to 1566.72nm, a channel spacing of 0.4nm, and a wavelength accuracy of 0.02nm;

[0053] The CWDM laser transmitter module outputs a stable wavelength range of 1270nm to 1610nm and 18 channels of optical signals;

[0054] The PON laser transmitter module outputs an optical signal with a wavelength of 1650nm;

[0055] The control module realizes all driving control of the DWDM laser emission module through control instructions, mainly including TEC control, reference tool etalon micro-control, phase micro-control, grating micro-control, SOA micro-control and left and right reflector micro-control; realizes channel control of CWDM laser emission module and pulse control of PON laser emission module, etc.

[0056] The DWDM laser transmitting module mainly uses DBR tuning technology, and controls the operation of the driving unit by issuing instructions through the control module, and performs TEC control, reference tool standard tool micro-control, phase micro-control, grating micro-control, SOA micro-control, left and right reflector micro-control, control algorithm, etc., so as to ensure the stability of the output wavelength and the consistency of power. The DWDM laser transmitting module can ultimately ensure the output wavelength tuning range of 1528.77nm~1566.72nm, output 96 wavelength channels, the channel spacing can reach 0.4nm, and the wavelength accuracy can reach 0.02nm;

[0057] The CWDM laser transmission module adopts semiconductor laser control technology to achieve a stable output wavelength range of 1270nm to 1610nm, output 18 wavelength channels, and the channel interval is 20nm;

[0058] The present invention has the following advantages:

[0059] (1) This device integrates three light sources and uses the following optical path connection method to control the optical switch to output the pulse signals of the DWDM light source, CWDM light source, and 1650nm PON light source from one optical interface. Among them, DWDM contains 96 wavelengths, CWDM light source contains 18 wavelengths, and 1650PON light source has one wavelength, totaling 115 wavelengths. This device only needs to control the optical switch to switch channels during the transmission and reception process through the master control module, so that one device and one optical interface can cover the OTDR test of three light sources with a total of 115 optical wavelengths. This highly integrated test device is suitable for long-distance, large-capacity, multi-standard integrated high-speed optical network construction, acceptance, maintenance and other fields. A single device is easy to carry, which not only saves equipment costs, but also simplifies the test operation steps, which can effectively improve the construction and operation and maintenance efficiency of the integrated optical network;

[0060] (2) The device of the present invention has made innovations and optimizations in the processing of multiple modules, so that the original entire serial measurement method has been transformed into a parallel array operation, which has improved the measurement efficiency and reduced the overall measurement time. The multiplexing structure also uses a time-division multiplexing method for data processing. When the data processing time of the processing module is short, the frequency of the multiplexing structure operation clock can be increased to increase the number of multiplexing channels and the data processing speed, so that the data of each channel can be processed and analyzed quickly in a timely manner.

[0061] (3) The DWDM laser emitting unit of the present invention is a tunable C-band laser emitting unit, which mainly uses DBR tuning technology. In terms of hardware, the master control module issues instructions to control the operation of the driving unit, and performs left and right grating micro-control, phase micro-control, SOA micro-control, temperature control, gain current micro-control, etc. on it, so as to ensure the stability of the output wavelength and the consistency of power. In view of the high sensitivity of DBR lasers to temperature, temperature changes will change the refractive index of the laser and thus change the output wavelength, so a TEC refrigeration device is used to adjust the laser temperature to ensure that the laser temperature is within the set range.

[0062] (4) The existing OTDR test device needs to transmit through different optical interfaces when testing different light sources. The three tests of CWDM OTDR, DWDM OTDR and PON OTDR require three instruments or three optical interfaces of a combination instrument. When testing different wavelength light sources in the same link, it is necessary to switch the optical connection interface. The device structure is complex and the operation is inconvenient. The present invention can quickly realize the control of the channel through the design of the light source output optical path, the combination of the optical switching unit with the photoelectric detection unit and the high-speed data acquisition and analysis unit, and can quickly switch to the corresponding light source test channel by controlling the optical switch through the master control module, thereby ensuring that the transmission signal is timely switched to the channel and the return signal can be captured and processed in time.

[0063] (5) The present invention uses filtering processing to retain edge information while reducing noise, and simplifies and approximates the processing algorithm to reduce the amount of calculation. It uses bilateral filtering for the 25,600-point trace, which takes about 10 seconds, greatly improving the data processing time. The noise comparison between the processed trace and the original trace is as follows. The overall trace is smoother, the noise reduction effect is obvious, and the trace event area is completely retained. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a schematic diagram of a three-in-one wavelength division multiplexing optical time domain reflectometer system;

[0065] Figure 2 It is a partial structural diagram of a three-in-one wavelength division multiplexing optical time domain reflectometer system;

[0066] Figure 3 It is a flow chart of a control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system;

[0067] Figure 4 It is a flow chart of step S1 of a control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system;

[0068] Figure 5 It is a flow chart of step S2 of a control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system;

[0069] Figure 6 It is a schematic diagram of a DWDM laser transmitting module in Embodiment 3 of a three-in-one wavelength division multiplexing optical time domain reflectometer system and a control method thereof;

[0070] Figure 7 It is a trace diagram of Embodiment 3 of a three-in-one wavelength division multiplexing optical time domain reflectometer system and control method thereof;

[0071] Figure 8 This is a partial enlarged view of the trace of Example 3 of a three-in-one wavelength division multiplexing optical time domain reflectometer system and its control method.

[0072] Reference numerals:

[0073] 1. Laser emission module; 11. DWDM laser emission module; 12. CWDM laser emission module; 13. PON laser emission module; 2. Optical switching module; 21. First circulator; 22. Second circulator; 23. First optical switch; 24. Second optical switch; 3. Optical coupling module; 31. Optical coupler; 32. First wavelength division multiplexer; 33. Second wavelength division multiplexer; 4. Three-in-one optical port; 5. Optical detection and receiving module; 6. Amplification module; 7. Data acquisition and analysis module; 8. Control module. DETAILED DESCRIPTION

[0074] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0075] Example 1

[0076] like Figures 1-2 As shown, a three-in-one wavelength division multiplexing optical time domain reflectometer system includes a laser emitting module 1, an optical switching module 2, an optical coupling module 3, and a three-in-one optical port 4 optically connected in sequence, an optical detection receiving module 5, an amplification module 6, a data acquisition and analysis module 7 connected in sequence to the optical switching module 2, and a control module 8 electrically connected to the laser emitting module 1 and the data acquisition and analysis module 7;

[0077] The laser emission module 1 includes a DWDM laser emission module 11, a CWDM laser emission module 12 and a PON laser emission module 13 which are arranged in parallel. The DWDM laser emission module 11, the CWDM laser emission module 12 and the PON laser emission module 13 are all optically connected to the optical switching module 2, and the DWDM laser emission module 11, the CWDM laser emission module 12 and the PON laser emission module 13 are all electrically connected to the control module 8;

[0078] The control module 8 drives the DWDM laser emission module 11, the CWDM laser emission module 12 and the PON laser emission module 13 to emit pulse light. The control module 8 analyzes and judges the test data output by the data acquisition and analysis module 7 and adjusts the emission wavelengths of the DWDM laser emission module 11, the CWDM laser emission module 12 and the PON laser emission module 13; the optical switching module 2 performs channel switching during the pulse signal emission and reception process of the DWDM laser emission module 11, the CWDM laser emission module 12 and the PON laser emission module 13 under the control of the control module 8; the optical coupler The combining module 3 couples the pulse signals output by the DWDM laser light source 11, the CWDM laser light source 12 and the PON laser light source 13 to the optical fiber under test through the three-in-one optical port 4, and transmits the reflected signal and the scattered signal in the optical fiber under test back to the optical detection receiving module 5 through the three-in-one optical port 4 and the optical switching module 2. The optical detection receiving module 5 detects and collects the signals in the optical fiber under test and outputs them after photoelectric conversion. The amplification module 6 receives the signals output by the optical detection receiving module 5 and outputs them after conditioning and amplification. The data acquisition and analysis module 7 receives the signals output by the amplification module 6 and outputs them to the control module 8 after analysis.

[0079] The optical switching module 2 includes a first circulator 21 optically connected to the output end of the DWDM laser emitting module 11, a second circulator 22 optically connected to the output end of the PON laser emitting module 13, a first optical switch 23 optically connected to the output end of the photoelectric detection receiving module 5, and a second optical switch 24 optically connected to the optical coupling module 3;

[0080] The optical coupling module 3 includes an optical coupler 31, a first wavelength division multiplexer 32 and a second wavelength division multiplexer 33;

[0081] The first wavelength division multiplexer 32 is optically connected to the first circulator 21, the second circulator 22 and the first optical switch 23, the second wavelength division multiplexer 33 is optically connected to the first circulator 21, the second circulator 22 and the second optical switch 24, the input end of the coupler 31 is optically connected to the first optical switch 23 and the output end of the CWDM laser transmitter module 12, the input end of the second optical switch 24 is optically connected to the optical coupler 31 and the second wavelength division multiplexer 33, and the output end of the second optical switch 24 is connected to the three-in-one optical port 4;

[0082] The DWDM laser transmitting module 11 outputs a 96-channel optical signal with a wavelength tuning range of 1528.77nm to 1566.72nm, a channel spacing of 0.4nm, and a wavelength accuracy of 0.02nm. The CWDM laser transmitting module 12 outputs an 18-channel optical signal with a wavelength range of 1270nm to 1610nm and a channel spacing of 20nm. The wavelength of the optical signal output by the PON laser transmitting module 13 is 1650nm.

[0083] The DWDM laser transmitting module 11 is a modulated grating Y-branch variable wavelength laser using an integrated semiconductor optical amplifier;

[0084] The CWDM laser transmitting module 12 is a DBF laser;

[0085] The first optical switch 23 and the second optical switch 24 are integrated waveguide optical switches.

[0086] The data acquisition and analysis module 7 filters the measurement points. The data acquisition and analysis module 7 includes a channel selection module, a data receiving module, a data processing module, a data buffer module and a result output module.

[0087] Example 2

[0088] like Figures 3 to 5 As shown, a control method for a three-in-one wavelength division multiplexing optical time domain reflectometer system includes the following steps:

[0089] S1, the control module 8 drives the laser emission module 1 to emit pulse light through wavelength division multiplexing and outputs it to the optical fiber under test through the optical switching module 2, the optical coupling module 3, and the three-in-one optical port 4. The laser emission module 1 includes a DWDM laser emission module 11, a CWDM laser emission module 12, and a PON laser emission module 13 arranged in parallel;

[0090] S11, the control module 8 drives the DWDM laser emitting module 11, the CWDM laser emitting module 12 and the PON laser emitting module 13 to emit pulsed light through wavelength division multiplexing and outputs it to the optical fiber under test through the three-in-one optical port 4, the DWDM laser emitting module 11 outputs and enters step S12, the CWDM laser emitting module 12 outputs and enters step S13, and the PON laser emitting module 13 outputs and enters step S14;

[0091] S12, the control module 8 drives the DWDM laser emitting module 11 to emit pulsed laser output to the optical switching module 2, which is sequentially output to the three-in-one optical port 4 after passing through the first circulator 21, the second wavelength division multiplexer 33, and the second optical switch 24, and then enters step S2;

[0092] S13, the control module 8 drives the CWDM laser emitting module 12 to emit pulsed laser output, which is sequentially output to the three-in-one optical port 4 after passing through the optical coupler 31 and the second optical switch 24, and then enters step S2;

[0093] S14, the control module 8 drives the PON laser light source 13 to emit pulsed laser output to the optical switching module 2, which is sequentially output to the three-in-one optical port 4 after passing through the second circulator 22, the second wavelength division multiplexer 33, and the second optical switch 24, and then enters step S2;

[0094] S2, echo detection: the control module 8 analyzes and judges the test data through the light detection receiving module 5, the amplification module 6 and the data acquisition and analysis module 7;

[0095] S21, the control module 8 detects and collects the pulse signal reflection and scattered signals of the DWDM laser light source 11, the CWDM laser light source 12, and the PON laser light source 13 in the measured link through the optical detection receiving module 5, and the detection signal collection of the DWDM laser light source 11 enters step S22, the detection signal collection of the CWDM laser light source 12 enters step S23, and the detection signal collection of the PON laser light source 13 enters step S24;

[0096] S22, after the detection signal of the DWDM laser light source 11 is input through the three-in-one optical port 4, it passes through the second optical switch 24, the second wavelength division multiplexer 33, the first circulator 21, the first wavelength division multiplexer 32, the first optical switch 23 in sequence and then inputs into the optical detection receiving module 5, and enters step S25;

[0097] The DWDM laser light source 11 is provided with left and right grating micro-control, phase micro-control, SOA micro-control, temperature control and gain current micro-control. The DWDM laser light source 11 controls the output wavelength through left and right reflectors and phase current, and controls the output power through gain and semiconductor optical amplifier current.

[0098] The laser emission process of the DWDM laser light source 11 is as follows: the two reflectors on one side of the laser resonant cavity have at least one reflection peak. When the laser is working, the current is injected to tune the reflector. The two reflected lights are superimposed together through a 1*2 combiner or splitter to improve the reflectivity of the front end and generate a comb-shaped reflection spectrum. The Bragg grating groups at both ends of the laser generate different comb-shaped reflection spectra. When the light is reflected back and forth between the two ends of the laser, the superposition of the two different reflection spectra can obtain the required wavelength range.

[0099] S23, the detection signal of the CWDM laser light source 12 is input through the three-in-one optical port 4, and then passes through the second optical switch 24, the coupler 31, and the first optical switch 23 in sequence and then input into the optical detection receiving module 5, and then enters step S25;

[0100] The CWDM laser light source 12 controls the operation of the DBF laser through a driving circuit;

[0101] S24, after the detection signal of the PON laser emission module 13 is input through the three-in-one optical port 4, it passes through the second optical switch 24, the second wavelength division multiplexer 33, the second circulator 22, the first wavelength division multiplexer 32, and the first optical switch 23 in sequence, and then inputs into the optical detection receiving module 5, and enters step S25;

[0102] The PON laser light source 13 controls the operation of the driving module by sending instructions through the master control module;

[0103] S25, the optical detection receiving module 5 performs photoelectric conversion on the detection signals of the DWDM laser light source 11, the CWDM laser light source 12, and the PON laser light source 13, and then outputs the converted signals to the amplification module 6, and the amplification module 6 amplifies the detected signals through differential processing, logarithmic processing, and virtual ground processing, and then outputs the amplified signals to the data acquisition and analysis module 7;

[0104] S26, the data acquisition and analysis module 7 receives the detection signal and performs filtering and analysis processing and then outputs it to the control module 8, the control module 8 compares the wavelength of the detection signal with the initial set wavelength and then fine-tunes the current so that the wavelength of the emitted laser meets the accuracy requirement;

[0105] The data acquisition and analysis module 7 uses a multi-channel control multiplexing structure; the channel selection module of the data acquisition and analysis module 7 selects the signal receiving channel, and the corresponding data receiving module receives the signal data and outputs it to the data processing module for data analysis and processing. The processing data is temporarily stored in the data cache module. After the data processing is completed, the result is output through the result output module. The channel selection module coordinates the operation of the data receiving module, the data processing module, the data cache module and the result output module;

[0106] The data acquisition and analysis module 7 uses a filtering algorithm of five-point cubic smoothing and least squares fitting:

[0107]

[0108] Among them, y x is the pixel value of the measurement point x, is the filtered value of the measurement point x.

[0109] Example 3

[0110] like Figures 1-2 As shown, a three-in-one wavelength division multiplexing integrated optical time domain reflectometer system includes:

[0111] The control module 8 can control the DWDM laser emission module 11, the CWDM laser emission module 12, and the PON laser emission module 13 to emit pulse light; and is responsible for analyzing and judging the test data sent by the data acquisition and analysis module 7 to obtain the test results;

[0112] The laser emission module 1 drives the corresponding laser emission module to emit an optical signal after receiving the instruction sent by the control module 8, including a DWDM laser emission module 11, a CWDM laser emission module 12, and a PON laser emission module 13;

[0113] DWDM laser emitting module 11, the control module 8 controls the driver to precisely control the DWDM laser emitting module 11, including a wavelength micro-control circuit, a power micro-control circuit and a TEC micro-control circuit, and realizes wavelength micro-control by controlling the current of the left and right reflection Bragg gratings, phase, wavelength reference tools and other standard tools of the DWDM laser emitting unit, and realizes power micro-control by controlling the current of the SOA, wavelength reference tools and other standard tools;

[0114] When the DWDM laser transmitting module 11 is working, the current is injected to tune them, and the two reflected lights are superimposed together through the 1*2 combiner / splitter to optimize the reflectivity of the front end, so that the laser can obtain high power output in the entire tuning range; this will produce a comb-shaped reflection spectrum, and the Bragg grating groups at both ends of the laser produce different comb-shaped reflection spectra. When the light is reflected back and forth between them, the two different reflection spectra are superimposed, and a wider wavelength range can be obtained. The excitation circuit used in this technology is complex, but its adjustment speed is very fast, the wavelength adjustment range is wide, and the circuit microcontroller design is reasonable to make the output tunable laser high in power, stable in wavelength, narrow in pulse width, and fast in tuning speed. The emission wavelength tuning range is 1528.77nm~1566.72nm, the channel interval is 0.4nm, and the wavelength accuracy is 0.02nm; the 96 channel wavelengths are 1528.77nm, 1529.16nm, 1529.55nm, 1529.94nm, 1530.33nm, 1530.72nm, 1531.12nm, 1531.51nm, 1531.90nm, 1532.29nm, 1532.68nm, 1533.07nm, 1533.47nm, 1533.86nm, 1534.25nm, 1534.64nm, 1535.04nm, 1535.43nm, 1535.82nm, 1536.22nm, 1536.61nm, 1537.00nm, 1537.4 0nm, 1537.79nm, 1538.19nm, 1538.58nm, 1538.98nm, 1539.37nm, 1539.77nm, 1540.16nm, 1540.56nm, 1540.95nm, 15 41.35nm, 1541.75nm, 1542.14nm, 1542.54nm, 1542.94nm, 1543.33nm, 1543.73nm, 1544.13nm, 1544.53nm, 1544.92 nm, 1545.32nm, 1545.72nm, 1546.12nm, 1546.52nm, 1546.92nm, 1547.32nm, 1547.72nm, 1548.11nm, 1548.51nm, 154 8.91nm, 1549.32nm, 1549.72nm, 1550.12nm, 1550.52nm, 1550.92nm, 1551.32nm, 1551.72nm, 1552.12nm, 1552.52nm , 1552.93nm, 1553.33nm, 1553.73nm, 1554.13nm, 1554.54nm, 1554.94nm, 1555.34nm, 1555.75nm, 1556.15nm, 1556.55nm, 1556.96nm, 1557.36nm, 1557.77nm, 1558.17nm, 1558.58nm, 1558.98nm , 1559.39nm, 1559.79nm, 1560.20nm, 1560.61nm, 1561.01nm, 1561.42nm, 156 1.83nm, 1562.23nm, 1562.64nm, 1563.05nm, 1563.45nm, 1563.86nm, 1564.27 nm, 1564.68nm, 1565.09nm, 1565.50nm, 1565.90nm, 1566.31nm, 1566.72nm;.

[0115] The CWDM laser transmitting module 12 is controlled by the driver controlled by the control module 8, and can emit a stable wavelength range of 1270nm to 1610nm by driving and controlling the DFB laser to ensure the laser output with a wavelength interval of 20nm; the 18 channel wavelengths are 1270nm, 1290nm, 1310nm, 1330nm, 1350nm, 1370nm, 1390nm, 1410nm, 1430nm, 1450nm, 1470nm, 1490nm, 1510nm, 1530nm, 1550nm, 1570nm, 1590nm, and 1610nm respectively;

[0116] The PON laser transmitting module 13 is controlled by the driver of the control module 8 and can transmit an optical signal with a wavelength of 1650nm;

[0117] The optical switching module 2 is controlled by the control module 8 to realize the channel switching during the pulse signal transmission and reception of the DWDM laser transmission module 11, the CWDM laser transmission module 12, and the PON laser transmission module 13. The control module 8 issues instructions to control the nanosecond switching of channels for different test requirements.

[0118] The optical coupling module 3 couples the pulse signals of the DWDM laser light source, the CWDM laser light source and the PON laser light source to the output of the three-in-one optical port 4, and transmits the reflected and scattered signals in the measured link back to the photoelectric detection receiving module 5.

[0119] The optical detection receiving module 5 detects and collects the pulse signal reflection and scattered signals of the DWDM laser light source, CWDM laser light source and PON laser light source in the measured link through the optical coupling module 5 to realize the photoelectric conversion function.

[0120] Amplifying module 6, conditioning and amplifying the signal output by photoelectric detection receiving module 5;

[0121] Data acquisition and analysis module 7, high-performance FPFA reads the signal received from the amplification module 6, and automatically sets the detection threshold and the required laser pulse speed and intensity according to the actual link situation through digital filtering, amplitude extraction, least squares method, Gaussian algorithm and other algorithm analysis and processing, and effectively distinguishes useful information from interference factors;

[0122] Three-in-one optical port 4 injects the optical pulse emitted by the coupler module 3 into the optical fiber under test;

[0123] 1.DWDM laser transmitter module;

[0124] Most DWDM system light sources on the market today use variable wavelength DFB lasers. DFB variable wavelength lasers usually change wavelengths by adjusting temperature, but the higher the temperature, the lower the output power. In applications where the variable wavelength range is not demanding, changing the laser center temperature to change the output wavelength is a mature technology. DFB variable wavelength lasers are generally used in applications where the wavelength does not change for a long time after being set in DWDM systems, because temperature changes are relatively slow and cannot change instantaneously, and changes in the laser's current will also cause temperature changes, thereby changing the output wavelength. Therefore, how to ensure that the wavelength does not exceed the range and affect adjacent wavelength communications when turning on and off the laser and changing the wavelength requires relatively complex circuit control. In applications where the wavelength changes at any time, such as OTDR, in DWDM systems, to ensure that the wavelength does not exceed the range, both the hardware and software are very complex.

[0125] like Figure 6 As shown in the figure, this design uses a modulated grating Y-branch (MG-Y) variable wavelength laser with an integrated semiconductor optical amplifier (SOA) to achieve a tuning range of 1528nm to 1564nm, a channel spacing of 0.4 nanometers, and a wavelength accuracy of 0.02 nanometers. At the same time, by reverse biasing the SOA, the laser output will be attenuated by at least 40dB, which can effectively reduce the interference of operations such as changing the wavelength and turning the laser on and off on adjacent wavelengths. It also reduces the cost of complex real-time automatic temperature control circuits.

[0126] The variation range of a single DBR laser is generally <1THz (8nm) and cannot fully cover the complete C-band or L-band. Therefore, this design uses a modulated grating Y-branch (MG-Y) variable wavelength laser integrated with a semiconductor optical amplifier (SOA) to expand the wavelength variation range and meet the requirements of the DWDM system.

[0127] The laser mainly controls the output wavelength through left and right reflectors and phase current, and controls the output power through gain (GAIN) and semiconductor optical amplifier (SOA) current. If the SOA is reverse biased, the laser output will be attenuated by at least 40dB, which can effectively reduce the interference of operations such as changing wavelength and turning the laser on and off on adjacent wavelengths.

[0128] The two reflectors on one side of the laser resonant cavity have multiple reflection peaks. When the laser is working, current is injected to tune them. The two reflected lights are superimposed together through a 1*2 combiner / splitter to optimize the reflectivity of the front end, so that the laser can obtain high-power output in the entire tuning range. This will produce a comb-shaped reflection spectrum. The Bragg grating groups at both ends of the laser produce different comb-shaped reflection spectra. When the light reflects back and forth between them, the superposition of two different reflection spectra results in a wider wavelength range. This technology has a very fast adjustment speed and a wide wavelength adjustment range. A reasonable circuit microcontroller design can make the output tunable laser have high power, stable wavelength, narrow pulse width, and fast tuning speed.

[0129] The main advantages of this design are:

[0130] 1) Improved wavelength stability when changing wavelength.

[0131] 2) It reduces the complex circuits for turning on and off the laser and changing the wavelength, thus reducing the overall cost.

[0132] like Figures 3 to 5 As shown, the specific control method and steps of the control module;

[0133] The master control module controls the three laser emission units separately:

[0134] DWDM laser transmitting unit 11: The tunable C-band laser transmitting unit mainly uses DBR tuning technology. In terms of hardware, the master control module issues instructions to control the operation of the driving unit, and performs left and right grating micro-control, phase micro-control, SOA micro-control, temperature control, gain current micro-control, etc., to ensure the stability of the output wavelength and the consistency of power. In view of the high sensitivity of DBR lasers to temperature, temperature changes will change the refractive index of the laser and thus change the output wavelength, so TEC cooling equipment is used to adjust the laser temperature to ensure that the laser temperature is within the set range.

[0135] The D / A converter uses 14-bit resolution and can set various parameters independently to meet the required current control accuracy, including:

[0136] The current range of LEFT and RIGHT is 0-35mA;

[0137] The current range of PHASE is 0-8mA;

[0138] The current range of GAIN is 0-100mA;

[0139] The current range of the SOA is 0-170mA.

[0140] The output laser passes through a 95:5 splitter, and 5% of the optical signal enters the feedback circuit, passes through the wavelength detection and A / D conversion module, and is compared with the initial wavelength after signal analysis. If the monitored wavelength deviates greatly from the set wavelength, each current is fine-tuned after calculation until the emitted laser wavelength meets the deviation accuracy of ±0.02nm. The above design can achieve a channel spacing of 0.4nm in the wavelength range of 1528nm to 1564nm, and can output 96 wavelengths.

[0141] CWDM laser transmitting unit 12: adopts semiconductor laser control technology, controls the operation of DBF laser through driving circuit, transmits laser through 95:5 splitter, 5% of optical signal enters feedback circuit, passes through wavelength detection module and A / D conversion module, and is compared with initial wavelength after signal analysis. If the monitoring wavelength deviates greatly from the set wavelength, each current is fine-tuned after calculation until the emitted laser wavelength meets the deviation accuracy of ±0.02nm.

[0142] Online test laser emission unit 13: mainly using laser pulse control technology, the master control module issues instructions to control the operation of the drive module, performs laser pulse emission control on it, and emits a 1650nm±10nm wavelength light source.

[0143] 2. Methods and steps of data collection, processing and analysis

[0144] In the hardware circuit design and main program control program, multi-channel scheduling technology, pulse width precision control technology, pulse coding technology, precise detection and processing technology of weak signals are combined with data acquisition and processing algorithms to realize multi-channel testing in the same optical fiber.

[0145] The optical switching coupling unit mainly realizes the channel switching during the pulse signal transmission and reception of the tunable C-band laser light source 11, CWDM laser light source 12, and PON online test 1650nm laser pulse light source 13. The master control module issues instructions to control the nanosecond switching between channels with different test requirements to ensure that the test requirements are met. The optical switching unit is combined with the photoelectric detection unit and the high-speed data acquisition and analysis unit to quickly realize the control of the channel.

[0146] In order to process the data of each channel in time, in addition to selecting a large-capacity FPGA chip, the hardware design also adopts a multi-channel control multiplexing structure, which consists of a channel selection module, a data receiving module, a data processing module, a data cache module and a result output module:

[0147] The multi-channel control module selects the signal receiving channel, and the corresponding data receiving module completes the reception of the signal data. Then the data processing module performs data analysis and processing, and the processing process data is temporarily stored in the data cache module. After the data processing is completed, the result is output. The coordination of each module is coordinated by the multi-channel control module. The multi-channel multiplexing structure uses the time division multiplexing method for data processing. When the data processing time of the data processing module is short, the frequency of the multiplexing structure operation clock can be increased to increase the number of multiplexing channels and the data processing speed, so that the data of each channel can be processed and analyzed quickly in a timely manner, and the overall computing efficiency is improved by 1 / 3.

[0148] The data acquisition and reception of the signal adopts the precise detection and processing technology of weak signals, and amplifies the pulse signal with high fidelity through differential processing, logarithmic processing, and virtual ground processing;

[0149] The data processing module adopts a high-speed laser pulse precise positioning adaptive algorithm. Through channel adaptive selection, adaptive transformation of multiple algorithms, median filtering, Hough transform, cumulative averaging and other processing and fuzzy control technology, it automatically sets the detection domain value and the required laser pulse speed and intensity according to the actual link conditions, and effectively distinguishes useful information from interference factors.

[0150] At the same time, a filtering algorithm is used. Suppose that n = 2m + 1 measurement points are filtered before and after the current moment. Each measurement point is x = (-m, -m + 1, 0,,,, 0, 1, ... m-1, m). A k-1 order polynomial is used to fit it. The formula for the current observation value is as follows:

[0151] y x =a0+a1x+a2x 2 +…+a k-1 x k-1 (1)

[0152] y x is the pixel value of point x

[0153] a is the variable to be solved, which is used to fit the observed samples

[0154] The predicted values ​​of the previous and next moments can be calculated using formula (1), and a total of 2m+1 equations are obtained, forming a k-dimensional linear equation system. In order for the equation to have a solution, n>k must be satisfied. The fitting parameter A is determined by the least squares method, and the result is:

[0155]

[0156] Represented as a matrix:

[0157] Y (2m+1)×1 =X (2m+1)×k ·A k×1 +E (2m+1)×1 (3)

[0158] The least squares solution of the fitting parameter A is:

[0159] (4)

[0160] The model predicted or filtered value of Y is:

[0161] (5)

[0162] The relationship matrix between the filtered value and the observed value can be obtained:

[0163] B=X·(X T ·X) -1 ·X T (6)

[0164] Five-point cubic smoothing formula, m = 2, k = 3, from the above formula we can get:

[0165]

[0166] Then calculate the B matrix by the formula:

[0167]

[0168] Five smoothing formulas are obtained:

[0169]

[0170]

[0171]

[0172]

[0173]

[0174] y x is the pixel value of point x;

[0175] a is the variable to be solved, which is used to fit the observed samples;

[0176] A is the fitting parameter;

[0177] is the least squares solution of A;

[0178] y is the pixel value of the measurement point;

[0179] is the filtered value of the measurement point;

[0180] According to the above filtering algorithm, the trace is filtered, and the edge information is retained while reducing noise. At the same time, the algorithm is simplified and approximated to reduce the amount of calculation. Bilateral filtering is used for the 25,600-point trace, which takes about 10 seconds, greatly improving the data processing time. The noise comparison between the processed trace and the original trace is as follows. The overall trace is smoother, the noise reduction effect is obvious, and the trace event area is completely retained.

[0181] The improvement effect of the trace after using the filtering algorithm is as follows Figures 7-8 As shown:

[0182] 3. Problems and improvement effects of existing multi-wavelength test devices:

[0183] Existing OTDR test devices need to transmit through different optical interfaces when testing different light sources. The three tests of CWDM OTDR, DWDM OTDR, and PON OTDR require three instruments or three optical interfaces of a combination instrument. When testing different wavelength light sources on the same link, the optical connection interface needs to be switched. The equipment structure is complex and the operation is inconvenient.

[0184] Light source output optical path:

[0185] DWDM light source 11 → first circulator 21 → FDWM 2 (second wavelength division multiplexer 33) → second optical switch 24, injected into the optical fiber via the three-in-one interface 4;

[0186] PON light source 13 → second circulator 22 → FDWM 2 (second wavelength division multiplexer 33) → second optical switch 24, injected into the optical fiber via the three-in-one interface 4;

[0187] CWDM light source 12 → coupler 31 → second optical switch 24, injected into the optical fiber via the three-in-one interface 4;

[0188] OTDR signal acquisition optical path:

[0189] DWDM test signal: second optical switch 24 → FDWM 2 (second wavelength division multiplexer 33) → first circulator 21 → FDWM 1 (first wavelength division multiplexer 32) → first optical switch 23 → detection receiving module 5;

[0190] PON test signal: second optical switch 24 → FDWM 2 (second wavelength division multiplexer 33) → second circulator 22 → FDWM 1 (first wavelength division multiplexer 32) → first optical switch 23 → optical detection receiving module;

[0191] CWDM test signal: second optical switch 24 → coupler 31 → first optical switch 23 → detection receiving module 5;

[0192] The optical switch uses an integrated waveguide optical switch, which uses a fully solid-state Bodao chip inside. The response speed is 4 orders of magnitude higher than that of the MEMS optical switch, reaching 100ns, and it has high integration, low power consumption, ultra-low insertion loss, high isolation, and no static drift problem. The optical switch can be quickly switched to the corresponding light source test channel through the master control module, ensuring that the return signal can be captured and processed in time.

[0193] DWDM light source device: The main reason for the instability of the wavelength of the existing DBR light source is that the temperature change causes the wavelength drift. The DBR light source is easily affected by the device temperature and environment. Especially when the wavelength is switched, the change of current will affect the temperature change inside the laser, thereby causing temperature drift. The commonly used temperature compensation method changes the wavelength slowly, which affects the actual test results.

[0194] This device uses TEC control, with a response speed of milliseconds. With the addition of a wavelength detection module, it can monitor the output laser wavelength in real time. When the wavelength is offset, it can quickly calibrate and tune the laser wavelength for compensation. After adding the wavelength detection module, the output wavelength deviation can be controlled within 0.02nm. The device has high laser power output, stable wavelength, narrow pulse width, and fast tuning speed, which can meet the full performance test requirements of DWDM OTDR under 96 channels.

[0195] Multi-channel control multiplexing structure: Traditionally, multi-wavelength test and analysis of the same optical fiber mostly adopts a serial structure. The received signal is collected, processed, analyzed, and the test results are output. When testing multiple wavelengths, the time required is the accumulation of a single wavelength.

[0196] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A three-in-one wavelength division multiplexing optical time domain reflectometer system, characterized in that: It comprises a laser emission module (1), an optical switching module (2), an optical coupling module (3), and a three-in-one optical port (4) which are optically connected in sequence, an optical detection receiving module (5), an amplification module (6), and a data acquisition and analysis module (7) which are connected in sequence to the optical switching module (2), and a control module (8) which is electrically connected to the laser emission module (1) and the data acquisition and analysis module (7); The laser emission module (1) comprises a DWDM laser emission module (11), a CWDM laser emission module (12) and a PON laser emission module (13) arranged in parallel, the DWDM laser emission module (11), the CWDM laser emission module (12) and the PON laser emission module (13) are all optically connected to the optical switching module (2), and the DWDM laser emission module (11), the CWDM laser emission module (12) and the PON laser emission module (13) are all electrically connected to the control module (8); The optical switching module (2) comprises a first circulator (21) optically connected to the output end of the DWDM laser transmitting module (11), a second circulator (22) optically connected to the output end of the PON laser transmitting module (13), a first optical switch (23) optically connected to the output end of the optical detection receiving module (5), and a second optical switch (24) optically connected to the optical coupling module (3); The control module (8) drives the DWDM laser emission module (11), the CWDM laser emission module (12) and the PON laser emission module (13) to emit pulsed light; the control module (8) analyzes and judges the test data output by the data acquisition and analysis module (7) and adjusts the emission wavelengths of the DWDM laser emission module (11), the CWDM laser emission module (12) and the PON laser emission module (13); the optical switching module (2) switches the channels of the DWDM laser emission module (11), the CWDM laser emission module (12) and the PON laser emission module (13) during the pulse signal emission and reception process under the control of the control module (8); the optical coupling module (2) The module (3) couples the pulse signals output by the DWDM laser emission module (11), the CWDM laser emission module (12) and the PON laser emission module (13) into the optical fiber under test through the three-in-one optical port (4), and transmits the reflected signal and the scattered signal in the optical fiber under test back to the optical detection receiving module (5) through the three-in-one optical port (4) and the optical switching module (2); the optical detection receiving module (5) detects and collects the signal in the optical fiber under test and outputs it after performing photoelectric conversion; the amplification module (6) receives the signal output by the optical detection receiving module (5), conditions and amplifies it, and outputs it; the data acquisition and analysis module (7) receives the signal output by the amplification module (6), analyzes it, and outputs it to the control module (8).

2. The three-in-one wavelength division multiplexing optical time domain reflectometer system according to claim 1, characterized in that: The optical coupling module (3) comprises an optical coupler (31), a first wavelength division multiplexer (32) and a second wavelength division multiplexer (33); The first wavelength division multiplexer (32) is optically connected to the first circulator (21), the second circulator (22) and the first optical switch (23); the second wavelength division multiplexer (33) is optically connected to the first circulator (21), the second circulator (22) and the second optical switch (24); the input end of the optical coupler (31) is optically connected to the first optical switch (23) and the output end of the CWDM laser transmitter module (12); the input end of the second optical switch (24) is optically connected to the optical coupler (31) and the second wavelength division multiplexer (33); and the output end of the second optical switch (24) is connected to the three-in-one optical port (4).

3. The three-in-one wavelength division multiplexing optical time domain reflectometer system according to claim 1, characterized in that: The DWDM laser transmitting module (11) outputs a 96-channel optical signal with a wavelength tuning range of 1528.77nm to 1566.72nm, a channel spacing of 0.4nm, and a wavelength accuracy of 0.02nm. The CWDM laser transmitting module (12) outputs an 18-channel optical signal with a wavelength range of 1270nm to 1610nm and a channel spacing of 20nm. The PON laser transmitting module (13) outputs an optical signal with a wavelength of 1650nm.

4. The three-in-one wavelength division multiplexing optical time domain reflectometer system according to claim 1, characterized in that: The DWDM laser emission module (11) is a modulated grating Y-branch variable wavelength laser using an integrated semiconductor optical amplifier; The CWDM laser emission module (12) is a DBF laser; The first optical switch (23) and the second optical switch (24) are both integrated waveguide optical switches. The data acquisition and analysis module (7) filters the measurement points, and the data acquisition and analysis module (7) comprises a channel selection module, a data receiving module, a data processing module, a data buffer module and a result output module.

5. The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, a control module (8) drives a laser emission module (1) to emit pulsed light through wavelength division multiplexing and outputs the pulsed light to the optical fiber under test through an optical switching module (2), an optical coupling module (3), and a three-in-one optical port (4), wherein the laser emission module (1) comprises a DWDM laser emission module (11), a CWDM laser emission module (12), and a PON laser emission module (13) arranged in parallel; S2. Echo detection: the control module (8) analyzes and judges the test data through the light detection receiving module (5), the amplification module (6) and the data acquisition and analysis module (7).

6. The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system according to claim 5, characterized in that: Step S1 includes the following steps: S11, the control module (8) drives the DWDM laser emission module (11), the CWDM laser emission module (12) and the PON laser emission module (13) to emit pulsed light through wavelength division multiplexing and outputs the pulsed light to the optical fiber under test through the three-in-one optical port (4), the output of the DWDM laser emission module (11) enters step S12, the output of the CWDM laser emission module (12) enters step S13, and the output of the PON laser emission module (13) enters step S14; S12, the control module (8) drives the DWDM laser emission module (11) to emit pulsed laser to the optical switching module (2), which is then output to the three-in-one optical port (4) after passing through the first circulator (21), the second wavelength division multiplexer (33), and the second optical switch (24) in sequence, and then enters step S2; S13, the control module (8) drives the CWDM laser emission module (12) to emit pulsed laser output, which is sequentially output to the three-in-one optical port (4) after passing through the optical coupler (31) and the second optical switch (24), and then enters step S2; S14, the control module (8) drives the PON laser emission module (13) to emit a pulsed laser output to the optical switching module (2), which is then output to the three-in-one optical port (4) after passing through the second circulator (22), the second wavelength division multiplexer (33), and the second optical switch (24) in sequence, and then enters step S2.

7. The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system according to claim 5, characterized in that: Step S2 includes the following steps: S21, the control module (8) detects and collects the pulse signal reflection and scattered signals of the DWDM laser emitting module (11), the CWDM laser emitting module (12), and the PON laser emitting module (13) in the link under test through the optical detection receiving module (5), the detection signal collection of the DWDM laser emitting module (11) enters step S22, the detection signal collection of the CWDM laser emitting module (12) enters step S23, and the detection signal collection of the PON laser emitting module (13) enters step S24; S22, after the detection signal of the DWDM laser transmitting module (11) is input through the three-in-one optical port (4), it passes through the second optical switch (24), the second wavelength division multiplexer (33), the first circulator (21), the first wavelength division multiplexer (32), the first optical switch (23) in sequence, and then is input into the optical detection receiving module (5), and the process proceeds to step S25; S23, after the detection signal of the CWDM laser transmitting module (12) is input through the three-in-one optical port (4), it passes through the second optical switch (24), the optical coupler (31), and the first optical switch (23) in sequence and then input into the optical detection receiving module (5), and the process proceeds to step S25; S24, after the detection signal of the PON laser transmitting module (13) is input through the three-in-one optical port (4), it passes through the second optical switch (24), the second wavelength division multiplexer (33), the second circulator (22), the first wavelength division multiplexer (32), and the first optical switch (23) in sequence, and then input into the optical detection receiving module (5), and the process proceeds to step S25; S25, the optical detection receiving module (5) performs photoelectric conversion on the detection signals of the DWDM laser emitting module (11), the CWDM laser emitting module (12), and the PON laser emitting module (13), and outputs the converted signals to the amplification module (6); the amplification module (6) performs differential processing, logarithmic processing, and virtual ground processing on the detection signals, and then amplifies the signals and outputs the converted signals to the data acquisition and analysis module (7); S26, the data acquisition and analysis module (7) receives the detection signal and performs filtering and analysis processing on the signal before outputting it to the control module (8); the control module (8) compares the wavelength of the detection signal with the initially set wavelength and then fine-tunes the current so that the wavelength of the emitted laser meets the accuracy requirement.

8. The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system according to claim 7, characterized in that: In step S22, the DWDM laser emission module (11) is provided with left and right grating micro-control, phase micro-control, SOA micro-control, temperature control and gain current micro-control, and the DWDM laser emission module (11) controls the output wavelength through left and right reflectors and phase current, and controls the output power through gain and semiconductor optical amplifier current; In step S23, the CWDM laser emission module (12) controls the operation of the DBF laser through a driving circuit; In step S24, the PON laser emission module (13) sends instructions through the master control module to control the operation of the drive module; In step S26, the data acquisition and analysis module (7) uses a multi-channel control multiplexing structure; the channel selection module of the data acquisition and analysis module (7) selects a signal receiving channel, the corresponding data receiving module receives the signal data and then outputs it to the data processing module for data analysis and processing, the processing data is temporarily stored in the data cache module, and after the data processing is completed, the result is output through the result output module, and the channel selection module coordinates the operation of the data receiving module, the data processing module, the data cache module and the result output module.

9. The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system according to claim 8, characterized in that: In step S22, the laser emission process of the DWDM laser emission module (11) is as follows: two reflectors on one side of the laser resonant cavity have at least one reflection peak. When the laser is working, a current is injected to tune the reflector. The two paths of reflected light are superimposed together through a 1*2 combiner or splitter to improve the reflectivity of the front end and generate a comb-shaped reflection spectrum. The Bragg grating groups at both ends of the laser generate different comb-shaped reflection spectra. When the light is reflected back and forth between the two ends of the laser, the two different reflection spectra are superimposed to obtain the required wavelength range.

10. The control method of a three-in-one wavelength division multiplexing optical time domain reflectometer system according to claim 7, characterized in that: In step S26, the data acquisition and analysis module (7) uses a filtering algorithm of five-point cubic smoothing and least squares fitting: ； in, For measuring point The pixel value of For measuring point The filter value of .

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