CN115268066A - A wavelength selective switch with channel detection and automatic calibration - Google Patents

Abstract

The invention discloses a wavelength selective switch with channel detection and automatic calibration functions, which integrates an optical signal detection OCM module of an optical fiber communication channel and corrects the drift amount of the wavelength selective switch parameter along with the working temperature according to the measurement data of the OCM module, thereby improving the module integration level and the working stability of the wavelength selective switch; the invention adopts a light splitting mode in the wavelength selective switch, utilizes the photoelectric sensor array to measure the power, the bandwidth and the wavelength of the whole communication waveband in real time, and uses the measured power, the bandwidth and the wavelength as a reference for correcting the central frequency of the wavelength selective switch to correct the central frequency drift.

Description

A wavelength selective switch with channel detection and automatic calibration

technical field

The invention relates to the technical field of optical communication, in particular to a wavelength selective switch with channel detection and automatic calibration functions.

Background technique

The application and development of wavelength division multiplexing technology can transmit more different wavelengths in the same optical fiber, which greatly promotes the communication capacity of the optical communication system.

The optical communication network is mostly implemented with a ring and topology structure. ROADM can realize multiplexing and demultiplexing of optical signals at different nodes of the optical communication network, that is, flexible configuration and scheduling of any wavelength of any port, which improves the flexibility of optical network scheduling. sex.

WSS is the core module in the ROADM system. On the basis of optical signal detection through the OCM in the RODAM system, it can realize optical signal switching, attenuation or blocking of any wavelength or wavelength combination at any communication port. The principle of WSS technology is based on the fixed-period diffraction grating and space optical system for spatial expansion of communication wavelengths, using micro-mechanical structure MEMS or LCoS technology to achieve the deflection of beams of different wavelengths, thereby realizing the function of WSS itself.

Because WSS based on LCoS technology has a variable bandwidth modulation function, it is more flexible in the application of optical communication and has become the mainstream of the market. The principle is that different graphics of LCoS are displayed as different diffraction grating structures, so the direction of the beam can be realized. At the same time, LCoS is composed of many tiny pixels, so the graphics can be freely edited to achieve dynamic grid adjustment.

The application environment of optical communication equipment is relatively harsh, and it is required to work stably in a large temperature range (usually -5-70°C). WSS is usually realized by using a space optical structure, which has a long optical path and a complex structure. At the same time, gratings and LCoS Temperature is also relatively sensitive, so WSS itself usually has a temperature control function and cooperates with a correction algorithm. By measuring the performance of WSS itself at different temperatures, a fixed relationship is formed to correct the corresponding wavelength drift at different temperatures to achieve stable work.

In the existing patent (CN112596167A), when the repeatability of measured LCoS pixel position and wavelength varies with temperature is poor, it will affect the accuracy of WSS wavelength drift correction; in addition, adding a light source and an optical fiber, in LCoS Reserving a part of the area separately on the surface will occupy the effective working area of LCoS and reduce the utilization rate of LCoS; the third disadvantage is that only a single wavelength is monitored, and the drift of a single wavelength is used to represent the entire communication band, and the nonlinear relationship between them The correction accuracy of temperature drift will be reduced; the fourth disadvantage is that the power and wavelength stability of a single light source will affect the accuracy of wavelength drift correction.

In the existing patent (CN102879864), one-time parameter calibration is usually carried out when the product leaves the factory, and the wavelength is corrected according to this calibration curve. The premise is that the test curve must have good repeatability. If the repeatability is poor , affects the accuracy of wavelength correction; since the temperature sensor is usually placed close to the grating, the difference in temperature uniformity and consistency of the optical system will affect the repeatability of the curve, which puts forward high requirements on the product itself and the consistency of temperature control; if If an obvious wavelength deviation is found during the use of the product, the product needs to be removed from the optical network and re-calibrated, which will affect the continuity of optical communication.

Contents of the invention

The object of the present invention is to provide a wavelength selective switch with channel detection and automatic calibration functions, so as to solve the problems raised in the above-mentioned background technology.

To achieve the above object, the present invention provides the following technical solutions: a wavelength selective switch with channel detection and automatic calibration functions, the wavelength selective switch includes an optical fiber array, a polarization processing device, a collimator lens, an imaging device, a switch lens, an image Differential compensators, dispersion gratings and LCoS components;

The LCoS component is located at the focal point of the dispersion direction of the optical system and is horizontally fixed on the optical base plate. The LCoS component includes a light splitting component, an LCoS and an optical power detector array, wherein the photodetector array is not vertically placed with the LCoS.

Preferably, in the WSS module, the wavelength switching process is as follows:

The optical fiber array 101 is an optical input and output port;

The optical fiber output beam is delivered to the polarization processing device 102 by the optical fiber array 101;

The polarization processing device 102 converts the free polarization state of the light beam into the same polarization state;

Then enter the collimating lens 103, so as to preliminarily collimate the outgoing beam of the fiber;

Then enter the imaging device 104 and the switching lens 105 in turn, because the imaging device 104 and the switching lens 105 are in the dispersion and switching directions respectively, forming a 1:1 4F and 2F optical system to complete the optical coupling of the light beam;

Then enter the aberration compensation device to further improve the coupling efficiency of the optical system;

Then enter the dispersion grating, the dispersion grating expands the spectrum of the input optical system to the LCoS component 108 according to the wavelength;

At this time, the LCoS component 108 forms a grating in the switching direction, and then the light splitting component splits the light beam;

95% of the light energy is incident on the LCoS, and this proportion of light is used for the wavelength switching of the WSS module to realize the wavelength selection function;

A proportion of 5% of light energy is incident on the photodetector array. This proportion of light is used for real-time measurement of optical power and wavelength, monitoring the optical power and wavelength drift of the WSS module, and feeding back to the WSS module for correction.

Preferably, the light splitting ratio of the light splitting component can be other values.

Preferably, the photodetector array can be one group, two groups or other numbers, one group of which is placed on the dispersion focal plane of the wavelength selective switch.

Preferably, the light splitting component can be polarized light splitter or non-polarized light splitter.

Preferably, the photodetector array may be one or more rows of detection units.

Preferably, the correction processing method of the WSS module is as follows:

Calibration is carried out before the product leaves the factory. By controlling the working temperature of the WSS module, the WSS module can work in a stable state, and then set a specific LCoS pattern, respectively select the two ends and the middle of the communication band, and use the wide-spectrum light source covering the communication band. Carry out the spectral scanning of the WSS module and the photodetector array to obtain the corresponding relationship curve between the two, and store it as a reference parameter;

In the WSS working state, the spectral curve of the photodetector array is calculated and input into the wavelength, power and bandwidth information of the WSS module, and the information obtained by this can replace the function of the optical fiber signal detection module OCM, and combine the optical network crossover Perform LCoS graphic configuration according to the requirements of WSS module configuration to realize the wavelength switch function;

At the same time, the spectral center wavelength information obtained by the photodetector array is compared with the internal storage (before leaving the factory) information, so as to obtain the offset of the wavelength information input to the WSS module;

Finally, this offset is converted into the position offset of the LCoS graph, and the wavelength is corrected.

Compared with prior art, the beneficial effect of the present invention is:

The wavelength selective switch of the present invention integrates the optical signal detection OCM module of the optical fiber communication channel, and corrects the drift of the wavelength selective switch parameter with the working temperature according to the measurement data of the OCM module, thereby improving the integration degree of the module and the working stability of the wavelength selective switch;

The present invention adopts a spectroscopic method inside the wavelength selective switch, uses a photoelectric sensor array to measure the power, bandwidth and wavelength of the entire communication band in real time, and uses it as a reference for correcting the central frequency of the wavelength selective switch to correct the drift of the central frequency;

The present invention adopts the spectroscopic method, and uses the photoelectric sensor array to measure the power, bandwidth and wavelength of the entire communication band in real time. As a reference for wavelength correction, it has two advantages: one is to integrate the OCM function, integrate the OCM into the WSS module, and improve the integration speed and reduce costs;

The second is to measure the spectral characteristics of the entire communication band in real time, and perform the translation of the LCoS surface graph and the correction of the wavelength according to the measurement data. Compared with patent 1, the advantage is that there is no need to add a separate light source and reserve a separate area for LCoS, which improves the LCoS. The utilization rate and the indirect error caused by power measurement are reduced, and the accuracy of wavelength correction is improved.

The advantage of the present invention is that it can reduce the requirements on the accuracy and consistency of the WSS temperature, and at the same time monitor the wavelength drift of the entire optical module instead of the grating itself, thereby reducing the optical-mechanical design and process difficulty of the WSS and improving the Wavelength correction accuracy.

Description of drawings

Fig. 1 is a schematic diagram of the process structure of the present invention

Fig. 2 is a structural schematic diagram of the ROADM system of the present invention

Fig. 3 is the structural representation of WSS module of the present invention

Fig. 4 is the structural representation of LCoS component of the present invention

FIG. 5 is a schematic diagram of the spectrum curve tested in Example 1 of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The present invention provides a technical solution: a wavelength selective switch with channel detection and automatic calibration functions, combined with Figure 1, inside the WSS, the beam input to the WSS is subjected to beam splitting, and 95% of the light energy is used for WSS routine Function, 5% of the light energy is input to the photodetector array to realize the OCM function, and the wavelength drift correction of WSS is performed according to the measurement data.

In this embodiment, in combination with FIG. 2, the wavelength selective switch can be applied to the ROADM system for optical cross-connection processing, and the specific processing method is as follows:

The optical signal in the optical fiber enters the optical switch Switches through the signal transmission module Tx, then passes through the optical splitter module Spiltters and the optical power amplification module EDFA, and then enters the WSS. Scan the spectrum to confirm the wavelength and power information of the optical signal in the fiber, and then switch the wavelength through the WSS according to the spectrum information and scheduling configuration requirements, and then pass through the optical power amplification module EDFA and the splitter module Spiltters, and then enter through the optical switch Switches Signal receiving module Rx.

Wherein, the WSS module includes an optical fiber array 101, a polarization processing device 102, a collimating lens 103, an imaging device 104, a switching lens 105, an aberration compensator 106, a dispersion grating 107 and an LCoS component 108;

3 and 4, the LCoS component 108 is located at the focal point of the dispersion direction of the optical system, because the diameter of the spot in the dispersion direction is small, usually 10-30um, which facilitates switching of smaller bandwidth channels,

The LCoS component 108 includes a light splitting component 301, an LCoS 302, and an optical power detector array 303. In order to make the WSS optical structure compact and improve stability, the LCoS 302 is usually fixed horizontally on the optical base plate, and the light beam is refracted and incident on the LCoS by a reflector. , since the optical power detector array 303 is also placed on the dispersion focus of the WSS optical system, the unit size and unit number of the optical power detector array correspond to the LCoS in the direction of spectrum expansion, so as to facilitate parameter matching with the LCoS and improve the monitoring effect ,

At the same time, in order to reduce the influence of the photodetector array on the WSS signal, the photodetector array 303 and the LCoS302 are not vertically placed, so as to prevent the reflected light from the surface of the photodetector array from entering the port of the WSS module;

As mentioned above, in the WSS module, the wavelength switching process is as follows:

The optical fiber array 101 is an optical input and output port;

The optical fiber output beam is delivered to the polarization processing device 102 by the optical fiber array 101;

The polarization processing device 102 converts the free polarization state of the light beam into the same polarization state;

Then enter the collimating lens 103, so as to preliminarily collimate the outgoing beam of the fiber;

Then enter the imaging device 104 and the switching lens 105 in turn, because the imaging device 104 and the switching lens 105 are in the dispersion and switching directions respectively, forming a 1:1 4F and 2F optical system to complete the optical coupling of the light beam;

Then enter the aberration compensation device to further improve the coupling efficiency of the optical system;

Then enter the dispersion grating, the dispersion grating expands the spectrum of the input optical system to the LCoS component 108 according to the wavelength;

At this time, the LCoS component 108 forms a grating in the switching direction, and then the light splitting component splits the light beam;

95% of the light energy is incident on the LCoS, and this proportion of light is used for the wavelength switching of the WSS module to realize the wavelength selection function;

A proportion of 5% of light energy is incident on the photodetector array. This proportion of light is used for real-time measurement of optical power and wavelength, monitoring the optical power and wavelength drift of the WSS module, and feeding back to the WSS module for correction.

As mentioned above, the correction processing method of the WSS module is as follows:

For the calibration before the product leaves the factory, firstly control the WSS operating temperature to make the WSS work in a stable state, then set specific LCoS graphics, for example, set three graphics corresponding to 50GHz bandwidth, which are located at the two ends and the middle of the communication band, and finally use The wide-spectrum light source covering the communication band scans the spectrum of the WSS and the photodetector array to obtain a corresponding relationship curve between the two, which is stored as a reference parameter;

In the WSS working state, calculate the wavelength, power and bandwidth information input to the WSS from the spectral curve of the photodetector array, and use the obtained information to replace the OCM function, and combine the requirements of the optical network crossover for the WSS configuration to perform LCoS Graphical configuration to realize the wavelength switch function. At the same time, the spectral center wavelength information obtained by the photodetector array is compared with the internal storage (before leaving the factory) information to obtain the offset of the wavelength information input to the WSS, and convert this offset into The position of the LCoS pattern is shifted, and the wavelength is corrected.

In this embodiment, two wavelength signals are input into the WSS as an example, and combined with the tested spectral curve Figure 5, a detailed introduction is made:

First, through the fitting calculation of the test spectral line, the peak frequency of the input wavelength can be obtained, that is, the center frequency of the signal, bandwidth and optical energy, etc. This data can replace the OCM function, and the test data can be fed back to the LCoS, and according to the WSS wavelength and The configuration of the switching port requires the graphic setting of LCoS to complete the WSS function.

At the same time, the wavelength drift data can be obtained by comparing the measured spectral information with the WSS initial configuration information, and the shift data can be used to translate the LCoS graph, thereby achieving the effect of correcting the wavelength drift.

Since the photodetector array 303 is also placed on the optical focus of the WSS spectral dispersion direction, and the optical parameters received by the LCoS are the same, the wavelength information can be directly measured and compared and corrected without indirect correction by measuring the temperature information. The accuracy of wavelength drift correction is improved, and the influence of temperature measurement and optical system stability on the accuracy of wavelength drift correction is reduced.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (7)

1. A wavelength selective switch having channel detection and auto-calibration functions, characterized by: the wavelength selective switch comprises an optical fiber array 101, a polarization processing device 102, a collimating lens 103, an imaging device 104, a switching lens 105, an aberration compensator 106, a dispersion grating 107 and an LCoS assembly 108;

the LCoS assembly 108 is located at a focus of a dispersion direction of the optical system, and is horizontally fixed on the optical backplane, the LCoS assembly 108 includes a light splitting assembly 301, an LCoS302 and an optical power detector array 303, wherein the optical power detector array 303 is not vertically disposed with the LCoS 302.

2. A wavelength selective switch with channel detection and auto-calibration functions as claimed in claim 1, wherein the wavelength switching process is as follows:

the optical fiber array 101 is an optical input/output port;

the emergent light beam of the optical fiber is transmitted to a polarization processing device 102 by an optical fiber array 101;

the polarization processing device 102 converts the free polarization state of the light beam into the same polarization state;

then enters a collimating lens 103, so as to perform primary collimation on the emergent light beam of the optical fiber;

then the optical fiber enters the imaging device 104 and the switching lens 105 in sequence, and the imaging device 104 and the switching lens 105 are respectively in the dispersion and switching directions, so that a 1:1 4F and 2F optical systems for completing the optical coupling of the light beam;

then enters an aberration compensation device to further improve the coupling efficiency of the optical system;

then enters a dispersion grating which spreads the spectrum of the input optical system to the LCoS component 108 according to the wavelength;

at this time, the light splitting component of the LCoS component 108 splits the light beam;

the light energy with the proportion of 95 percent is incident to the LCoS, and the light with the proportion is used for wavelength switching of the WSS module to realize the wavelength selection function;

and light energy with the proportion of 5% is incident to the photoelectric detector array, the light with the proportion is used for measuring the light power and the wavelength in real time, the light power and the wavelength drift amount are monitored, and the light power and the wavelength drift amount are fed back to the WSS module for correction.

3. A wavelength selective switch with channel detection and auto-calibration functions as claimed in claim 2, wherein: the splitting ratio of the splitting component can be other values.

4. A wavelength selective switch with channel detection and auto-calibration functions as claimed in claim 2, wherein: the photodetector arrays may be in one, two, or other number, with one set being disposed on the wavelength selective switch dispersive focal plane.

5. A wavelength selective switch with channel detection and auto-calibration functions as claimed in claim 2, wherein: the light splitting component can be polarized light splitting or non-polarized light splitting.

6. A wavelength selective switch with channel detection and auto-calibration functions as claimed in claim 2, wherein: the photodetector array may be one or more rows of detection cells.

7. A wavelength selective switch with channel detection and auto-calibration functions as claimed in claim 2, wherein: the modification processing mode of the WSS module is as follows:

calibrating a product before delivery, enabling the WSS module to work in a stable state by controlling the working temperature of the WSS module, setting a specific LCoS graph, respectively selecting two ends and the middle of a communication waveband, and performing spectrum scanning on the WSS module and a photoelectric detector array by using a wide-spectrum light source covering the communication waveband to obtain a corresponding relation curve between the two curves to be used as a reference parameter for storage;

under the working state of the WSS, calculating a spectral curve of the photoelectric detector array, inputting the calculated spectral curve into wavelength, power and bandwidth information of the WSS module, replacing the function of an optical fiber signal detection module OCM with the obtained information, and carrying out LCoS graphic configuration by combining the requirement of optical network crossing on the WSS module configuration to realize the wavelength switching function;

meanwhile, the spectral center wavelength information obtained by the photoelectric detector array is compared with the internal storage (before leaving factory) information, so that the wavelength information offset input to the WSS module is obtained;

and finally, converting the offset into the position offset of the LCoS graph to correct the wavelength.

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