Crosstalk suppression method for wavelength-selective switch, and wavelength-selective switch

Abstract

The present invention relates to the technical field of optical communications, and in particular, relates to a crosstalk suppression method for a wavelength-selective switch, and a wavelength-selective switch. The method comprises: acquiring a light spot center of incident light on several pixel points on an LCOS chip; on the basis of the position of the light spot center, calculating a phase modulation amount that needs to be superimposed on each pixel point; and superimposing the phase modulation amount on an initial phase of the pixel point. By superimposing a phase modulation amount on an initial phase of each pixel point, the present invention adjusts the phase of an LCOS chip without the need for adding other elements to a WSS optical path, so as to compensate for an aberration of the WSS optical path, implement a port switching function of a WSS module, suppress crosstalk between adjacent output ports, and optimize the insertion loss of the output ports, thereby effectively improving the indexes and performance of the WSS module.

Description

Cross-talk suppression method of wavelength selective switch and wavelength selective switch

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the following patent application:

[0003] (1) Chinese patent application No. 202411117397.2, entitled "Cross-talk suppression method of wavelength selective switch and wavelength selective switch", filed on August 15, 2024 with the China Patent Office. TECHNICAL FIELD

[0004] The present application relates to the field of optical communication technology, in particular to a cross-talk suppression method of wavelength selective switch and wavelength selective switch. BACKGROUND

[0005] With the development of information technology into the 5G / F5G era, cloud services, data centers, artificial intelligence, and the Internet of Things are booming, and various types of information data streams not only have increasing demands for network traffic bandwidth, but also have a sharp increase in node exchange data throughput. To meet the needs of next-generation intelligent network applications, the importance of all-optical switching is increasing. Among them, the reconfigurable optical add-drop multiplexer (ROADM) system, which is based on the wavelength selective switch (WSS) module as the core, is the mainstream commercial solution for optical fiber communication optical switching. It has the characteristics of flexible scheduling, large switching capacity, low latency, and low power consumption, and is increasingly favored by operators and enterprise customers.

[0006] The liquid crystal on silicon (LCOS) optical switching chip can realize optical signal routing deflection switching by loading different phase grating images, and has extremely high reliability. It is currently the main solution for implementing flexible grid WSS technology. With the continuous development of all-optical networks, the network size is becoming larger and larger, which means that WSS needs to have a larger port number to support the improvement of the ROADM dimension, which also increases the difficulty of WSS optical path design and debugging, resulting in some aberrations in the WSS optical path, increasing the insertion loss of the WSS output port and the cross-talk of adjacent output ports.

[0007] Therefore, it is urgent to overcome the defects of the prior art in the technical field.

[0008] SUMMARY

[0009] The technical problem to be solved by the present application is that the difficulty of WSS optical path design and debugging is increased, resulting in part of the aberration of the WSS optical path, increasing the insertion loss of the WSS output port, and increasing the crosstalk of adjacent output ports.

[0010] The present application adopts the following technical solutions:

[0011] In the first aspect, the present application provides a crosstalk suppression method of a wavelength selective switch, comprising:

[0012] Obtaining the spot center of the incident light on the LCOS chip on a plurality of pixel points;

[0013] According to the position of the spot center, the phase modulation amount to be superimposed on each pixel point is calculated;

[0014] The phase modulation amount is superimposed on the initial phase of the pixel point.

[0015] Preferably, the obtaining of the spot center of the incident light on the LCOS chip on a plurality of pixel points specifically comprises:

[0016] Calculating the first theoretical insertion loss of the output port reduced when the incident light is blocked by half;

[0017] In turn, the phase of the first pixel point on the LCOS chip is set to 0, and the phases of other pixel points are the initial phase, and the first actual insertion loss of the output port is monitored; when the phase of the nth pixel point is set to 0, the first actual insertion loss is equal to the first theoretical insertion loss, and the position area of the nth pixel point is the spot center.

[0018] Preferably, when the wavelength selective switch is a Twin structure wavelength selective switch, the wavelength selective switch comprises a first fiber array collimator and a second fiber array collimator, the first fiber array collimator comprises a first input port and a plurality of first output ports, the second fiber array collimator comprises a second input port and a plurality of second output ports, the first input port corresponds to the first output port, the second input port corresponds to the second output port, and the obtaining of the spot center of the incident light on the LCOS chip on a plurality of pixel points comprises:

[0019] The plurality of pixel points are evenly divided into a first part and a second part to divide the LCOS chip into a first region and a second region, the first region corresponds to the first input port and the first output port, and the second region corresponds to the second input port and the second output port; wherein the total number of the pixel points is M, the first region corresponds to 1 to m1 pixel, and the second region corresponds to (m1+1) to M pixel;

[0020] acquire a first light spot center of a pixel point on the first region, acquire a second light spot center of a pixel point on the second region, calculate a phase modulation amount of the pixel point in the first region according to a position of the first light spot center, and calculate a phase modulation amount of the pixel point in the second region according to a position of the second light spot center.

[0021] Preferably, the acquiring of the first light spot center of the pixel point on the first region and the acquiring of the second light spot center of the pixel point on the second region comprise:

[0022] calculate a second theoretical insertion loss of the first output port when the optical signal of the first input port is blocked by half, and calculate a third theoretical insertion loss of the second output port when the optical signal of the second input port is blocked by half;

[0023] set the phase of the first pixel point to 0, set the phase of other pixel points to an initial phase, and monitor a second actual insertion loss of the first output port, wherein when the phase of the nth1 pixel point is set to 0, the second actual insertion loss is equal to the second theoretical insertion loss, and the position region of the nth1 pixel point is the first light spot center;

[0024] set the phase of the (m1+1)th pixel point to 0, set the phase of other pixel points to an initial phase, and monitor a third actual insertion loss of the second output port, wherein when the phase of the nth2 pixel point is set to 0, the third actual insertion loss is equal to the third theoretical insertion loss, and the position region of the nth2 pixel point is the second light spot center.

[0025] Preferably, the calculating of the phase modulation amount to be superimposed on each pixel point according to the position of the light spot center comprises:

[0026] the phase modulation amount superimposed on each pixel point is calculated according to the following formula

[0027] wherein x is the position of the pixel point, x center is the position of the light spot center, λ is the wavelength of the light, f is the focal length of the lens, and d is the pixel size.

[0028] Preferably, the lens focal length is determined in the following manner: a small lens is arranged in front of the LCOS chip, the focal point of the small lens is overlapped with the light spot center, and the lens focal length is the focal length of the small lens; after the lens focal length is determined, the small lens is removed.

[0029] Preferably, the method further comprises obtaining an initial phase of each pixel point, and the method for calculating the initial phase comprises:

[0030] obtaining the position of the pixel point and the number of pixel points in a grating period;

[0031] multiplying the position of the pixel point by 2π and dividing by the number of pixel points in a grating period to obtain the initial phase.

[0032] In a second aspect, the application provides a wavelength selective switch suitable for the crosstalk suppression method of the wavelength selective switch of the first aspect, comprising a fiber array collimator 1, a focusing lens 2, an LCOS chip 3 and a driving circuit 4; the focusing lens 2 is arranged between the fiber array collimator 1 and the LCOS chip 3;

[0033] The fiber array collimator 1 comprises an input port 10 and a plurality of output ports 11, the input port 10 is used to output collimated light signals, and the output port 11 is used to collimate light signals deflected by the LCOS chip 3;

[0034] The driving circuit 4 is used to adjust the phase of each pixel point on the LCOS chip 3 according to the crosstalk suppression method of the wavelength selective switch of the first aspect.

[0035] Preferably, the number of the fiber array collimator 1 is 2, specifically comprising a first fiber array collimator 12 and a second fiber array collimator 13, the first fiber array collimator 12 comprises a first input port 120 and a plurality of first output ports 121, the second fiber array collimator 13 comprises a second input port 130 and a plurality of second output ports 131, and the first fiber array collimator 12 and the second fiber array collimator 13 share the LCOS chip 3;

[0036] The wavelength selective switch further comprises a first lens 20 and a second lens 21, the first lens 20 is arranged between the first fiber array collimator 12 and the LCOS chip 3, and the second lens 21 is arranged between the second fiber array collimator 13 and the LCOS chip 3.

[0037] Preferably, the fiber array collimator 1 comprises a plurality of fiber arrays and a plurality of collimating lenses, and the plurality of fiber arrays and the plurality of collimating lenses are one-to-one coupled.

[0038] Compared with the prior art, the present application has the beneficial effects that: the present application adjusts the phase of the LCOS chip, compensates the aberration of the WSS optical path, realizes the port switching function of the WSS module, suppresses the adjacent port crosstalk of the output port, optimizes the insertion loss of the output port, and effectively improves the index and performance of the WSS module by superimposing the phase modulation amount on the initial phase of the pixel point without adding other elements in the WSS optical path. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained from these drawings without creative labor for those skilled in the art.

[0040] Fig. 1 is a schematic diagram of the overall structure of a wavelength selective switch provided by an embodiment of the present application;

[0041] Fig. 2 is a schematic diagram of the increase of the output port insertion loss and the adjacent port crosstalk caused by the optical path aberration of a wavelength selective switch provided by an embodiment of the present application;

[0042] Fig. 3 is a schematic diagram of the addition of a small lens to a wavelength selective switch provided by an embodiment of the present application;

[0043] Fig. 4 is a schematic diagram of the double-in double-out of a wavelength selective switch provided by an embodiment of the present application;

[0044] Fig. 5 is a schematic diagram of the overall flow of a crosstalk suppression method of a wavelength selective switch provided by an embodiment of the present application;

[0045] Fig. 6 is a schematic diagram of step 1 of a crosstalk suppression method of a wavelength selective switch provided by an embodiment of the present application;

[0046] Fig. 7 is a schematic diagram of the position of the spot center of a crosstalk suppression method of a wavelength selective switch provided by an embodiment of the present application;

[0047] Fig. 8 is a schematic diagram of the method of confirming the position of the spot center of the TWin structure of a crosstalk suppression method of a wavelength selective switch provided by an embodiment of the present application;

[0048] Fig. 9 is a schematic diagram of step 112 of a crosstalk suppression method of a wavelength selective switch provided by an embodiment of the present application;

[0049] Fig. 10 is a schematic diagram of the position of the two spot centers of a crosstalk suppression method of a wavelength selective switch provided by an embodiment of the present application;

[0050] Figure 11 is a flow diagram of step 2 of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0051] Figure 12 is a flow diagram of step 3 of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0052] Figure 13 is a diagram of a method of obtaining initial phases of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0053] Figure 14 is a diagram of a method of calculating diffraction angles of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0054] Figure 15 is a diagram of initial phases of an LCOS chip of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0055] Figure 16 is a diagram of output port insertion loss and adjacent port crosstalk before modulation of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0056] Figure 17 is a diagram of superimposed phase modulation of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0057] Figure 18 is a diagram of optimized phases of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0058] Figure 19 is a diagram of optimized output port insertion loss and adjacent port crosstalk of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0059] Figure 20 is a diagram of initial phases of an LCOS chip including two modules of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0060] Figure 21 is a diagram of superimposed phase modulation of a first module of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0061] Figure 22 is a diagram of superimposed phase modulation of a second module of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0062] Figure 23 is a diagram of superimposed phase modulation of a first module and a second module of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application;

[0063] Figure 24 is a diagram of optimized phases of two modules of a crosstalk suppression method of a wavelength selective switch according to an embodiment of the present application. DETAILED DESCRIPTION

[0064] In order to make the objects, technical solutions and advantages of the present application clearer, the following further describes the present application with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0065] Unless otherwise required by context, the term "comprises" or "comprising" in the specification and claims is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example" or "some examples" are intended to indicate that the described implementation, implementation or example is included in at least one embodiment or example of the present disclosure. The illustrative representation of the above terms does not necessarily mean the same embodiment or example. In addition, the specific features, structures, materials or characteristics described can be included in any one or more embodiments or examples in any appropriate manner, i.e. although they are carried in the embodiment or example of the above terms due to the order of appearance and location, they are not limited to the combination of one embodiment or example.

[0066] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present disclosure and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present disclosure.

[0067] In the description of the present application, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more features. In the description of the embodiments of the present disclosure, unless otherwise specified, the meaning of "multiple" is two or more. In addition, for example, in the description, the same type of nouns can also be described as two independent individuals by adding "A", "B" at the end, in which case the features limited by "A", "B" are only used for the purpose of distinguishing the same type of individual description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0068] In describing some embodiments, the use of "coupled" or "coupling" and "connected" or "connecting" along with their derivatives, can be used. For example, some embodiments can be described as being "connected" where directly connected to one another or to one another without intervening physical or electrical components. As another example, some embodiments can be described as being "coupled" where directly coupled to one another or to one another without intervening physical or electrical components. However, an embodiment disclosed herein can not necessarily be limited to these implementations. The embodiments disclosed herein are not necessarily limited in application to the details of construction, the arrangements of components, and the arrangement of steps set forth in the following description or illustrated in the drawings.

[0069] In the description of the present application, the expression "A and / or B" (wherein A and B represent specific features) includes the following three combinations: A alone, B alone, and a combination of A and B.

[0070] As used herein, "about," "approximately," or "substantially" with reference to a value includes the recited value and the average value within an acceptable range of deviation from the recited value, as determined by one of ordinary skill in the art considering the measurement in question and the error (i.e., limitations in the measurement system) associated with making the measurement of the particular quantity.

[0071] Furthermore, the technical features involved in each of the embodiments of the present application described below can be combined with each other as long as there is no conflict.

[0072] Embodiment 1:

[0073] Embodiment 1 of the present application provides a wavelength selective switch, which is suitable for the crosstalk suppression method of the wavelength selective switch described in the subsequent solutions, as shown in FIG. 1, which comprises a fiber array collimator 1, a focusing lens 2, an LCOS chip 3, and a driving circuit 4; the focusing lens 2 is arranged between the fiber array collimator 1 and the LCOS chip 3; the fiber array collimator 1 comprises an input port 10 and a plurality of output ports 11, the input port 10 is used to output collimated optical signals, and the output port 11 is used to collimate optical signals deflected by the LCOS chip 3; the driving circuit 4 is used to adjust the phase of each pixel point on the LCOS chip 3 according to the crosstalk suppression method of the wavelength selective switch described below.

[0074] The fiber array collimator 1 comprises a plurality of fiber arrays and a plurality of collimating lenses (not shown in the figure), and the plurality of fibers in the fiber array are one-to-one coupled with the plurality of collimating lenses, wherein the input port of one fiber serves as the input port 10, and the output ports of other fibers serve as the output ports 11, light is input from the input port, passes through the collimating lens, the focusing lens 2, and the LCOS chip 3, is diffracted by the phase grating on the LCOS chip 3, and is incident on one of the output ports. In this embodiment, the plurality of refers to two or more than two.

[0075] In an actual application scenario, as shown in FIG. 2, due to optical aberration in the WSS optical path, the focal point of the incident light beam after converging through the focusing lens 2 does not fall on the LCOS chip 3, the light diffracted by the LCOS chip 3 is deflected by a certain angle and cannot be normally incident on the target output port, the coupling efficiency is reduced, and part of the light energy can be transferred to the adjacent port of the target output port. The insertion loss of the output port is large, and the crosstalk of the adjacent output port is large. Therefore, without modulating the phase grating of the LCOS chip 3, to calibrate this part of the aberration, a lens is added in front of the LCOS chip 3 to make the focal point of the incident light fall on the LCOS chip 3 again, as shown in FIG. 3, a small lens 5 can be arranged between the focusing lens 2 and the LCOS chip 3, the focal point of the small lens 5 falls on the LCOS chip 3, and the small lens 5 is used for secondary converging of the light signal converged by the focusing lens 2.

[0076] In order to achieve the purpose of calibrating the aberration without adding a new element in the wavelength selective switch, in the scheme described in the subsequent embodiment of the present application, a phase modulation amount is superimposed on the initial phase of the phase grating, so as to achieve the effect of placing a small lens 5 in the wavelength selective switch for converging the light signal. The driving circuit 4 is used for loading different voltages on different pixel points of the LCOS chip 3, different voltages correspond to different phase modulation amounts, a phase grating is formed, the incident light is diffracted by the LCOS chip 3, so as to be deflected by a certain angle, and then is emitted from the corresponding output port through the focusing lens 2 and the fiber array collimator 1, so as to realize the port switching function of the WSS.

[0077] In general, a wavelength selection switch can include an input port, multiple output ports and an LCOS chip 3. In the embodiment of the present application, when the wavelength selection switch is a Twin structure wavelength selection switch, the wavelength selection switch includes two sets of fiber array collimators 1, and the two sets of fiber array collimators 1 share one LCOS chip 3. As shown in FIG. 4, the number of the fiber array collimators 1 is 2, specifically including a first fiber array collimator 12 and a second fiber array collimator 13, the first fiber array collimator 12 includes a first input port 120 and multiple first output ports 121, the second fiber array collimator 13 includes a second input port 130 and multiple second output ports 131, and the first fiber array collimator 12 and the second fiber array collimator 13 share one LCOS chip 3; a first lens 20 is arranged in the optical path where the first fiber array collimator 12 is located, a second lens 21 is arranged in the optical path where the second fiber array collimator 13 is located, the first lens 20 is arranged between the first fiber array collimator 12 and the LCOS chip 3, and the second lens 21 is arranged between the second fiber array collimator 13 and the LCOS chip 3. When determining the position of the spot center, the LCOS chip 3 is evenly divided into two regions, one part of the regions diffracts the light signal of the first fiber array collimator 12, and the other part of the regions diffracts the light signal of the second fiber array collimator 13.

[0078] Based on the wavelength selection switch provided in the above scheme, the embodiment of the present application further provides a crosstalk suppression method of the wavelength selection switch, as shown in FIG. 5, which includes the following steps.

[0079] In step 1, the spot center of the incident light on the LCOS chip 3 at a plurality of pixel points is obtained.

[0080] Among them, the LCOS chip 3 is provided with a plurality of pixel points, and the plurality of pixel points are arranged to form a phase grating, and the aberration is compensated by adjusting the phase of the pixel points.

[0081] In step 2, the phase modulation amount that needs to be superimposed on each of the pixel points is calculated according to the position of the spot center.

[0082] In step 3, the phase modulation amount is superimposed on the initial phase of the pixel points.

[0083] Among them, the initial phase mainly depends on the position of the pixel points, and the determination method of the initial phase is described below.

[0084] In addition to the above steps, after the phase modulation amount and the initial phase are calculated, the method further comprises: obtaining the light field of the incident light after modulation by the LCOS chip 3 according to the initial phase and the phase modulation amount.

[0085] The present application compensates for the aberration of the WSS optical path by superimposing the phase modulation amount on the initial phase of the pixel points without adding other elements in the WSS optical path, realizes the port switching function of the WSS module, suppresses the crosstalk of adjacent output ports, optimizes the insertion loss of the output port, and effectively improves the index and performance of the WSS module.

[0086] Before phase modulation is performed on each pixel point on the phase grating, the center of the light spot of the incident light on the LCOS chip 3 needs to be found first, and the superimposed phase modulation amount of each pixel point is determined according to the center of the light spot. The principle of the process of determining the center of the light spot is as follows. The light spot on the LCOS chip 3 is the energy distribution area of the light signal incident from the input port. When the light spot is partially blocked, the optical power passing through the LCOS chip 3 will decrease.

[0087] In the optical system, the insertion loss refers to the decrease in optical power caused by the introduction of a certain element in the system. In the scenario of the present embodiment, the insertion loss is the decrease in output optical power caused by the phase of some pixel points on the LCOS chip 3 being set to 0, which causes these pixel points to be unable to deflect light. In the LCOS chip 3, the phase of each pixel point can be independently controlled to modulate the light wave front. When the phase of a certain pixel point is set to 0, the pixel point has no deflection effect on the light, and the light will pass directly without deflection. When the light spot area is blocked by half, since the light spot radius is proportional to the amplitude of the light, when the light spot is blocked by half, the light spot radius is reduced by half, and the amplitude of the light is also reduced by half. Since the light intensity is proportional to the square of the amplitude of the light, when the amplitude of the light is reduced by half, the light intensity becomes 1 / 4 of the original. According to the formula I=kA 2 , where I is the light intensity, A is the amplitude of the light, and k is a proportional coefficient related to the properties of the light wave and environmental conditions. According to the formula of the insertion loss (dB) , where P out is the output power of the light, P in is the input power of the light, , the insertion loss (dB) will decrease by 6 dB when the light spot is blocked by half.

[0088] Based on the above theory, in step 1, when there is one input port and multiple output ports, the center of the light spot of the incident light on the LCOS chip 3 is obtained, as shown in FIG. 6, which specifically comprises:

[0089] In step 101, a first theoretical insertion loss of the output port when the incident light is blocked by half is calculated.

[0090] The first theoretical insertion loss is 6dB.

[0091] In step 102, the phase of the first pixel on the LCOS chip 3 is set to 0, and the phases of other pixels are set to initial phases. The first actual insertion loss of the output port 11 is monitored. When the phase of the nth pixel is set to 0, the first actual insertion loss is equal to the first theoretical insertion loss. The position area of the nth pixel is the center of the light spot.

[0092] That is, the position X of the center of the light spot center = n.

[0093] Referring to FIG. 7, first, the phase of the first pixel is set to 0, and the phases of other pixels are set to initial phases. Then, the phase of the second pixel is set to 0 (at this time, the phase of the first pixel is still 0), and the phases of other pixels are set to initial phases. In this way, when the phase of the 217th pixel is set to 0, the first actual insertion loss is equal to the first theoretical insertion loss. The position area corresponding to the 217th pixel is the center of the light spot.

[0094] When the wavelength selection switch is a Twin structure wavelength selection switch, the wavelength selection switch includes a first fiber array collimator 12 and a second fiber array collimator 13. The first fiber array collimator 12 includes a first input port 120 and a plurality of first output ports 121. The second fiber array collimator 13 includes a second input port 130 and a plurality of second output ports 131. The first input port 120 corresponds to the first output port 121, and the second input port 130 corresponds to the second output port 131. The light spot center of the incident light on the LCOS chip 3 is obtained, as shown in FIG. 8, which specifically includes:

[0095] In step 111, the plurality of pixels are divided into a first part and a second part to divide the LCOS chip 3 into a first region and a second region. The first region corresponds to the first input port 120 and the first output port 121, and the second region corresponds to the second input port 130 and the second output port 131. The total number of pixels is M, the first region corresponds to 1 to m1 pixels, and the second region corresponds to (m1+1) to M pixels.

[0096] In step 112, the first light spot center of the pixel points on the first region is acquired, the second light spot center of the pixel points on the second region is acquired, the phase modulation amount of the pixel points in the first region is calculated according to the position of the first light spot center, and the phase modulation amount of the pixel points in the second region is calculated according to the position of the second light spot center.

[0097] In one embodiment, when the number of pixels of the LCOS chip 3 is 1200, the phase grating formed by the first 600 pixels is used for selectively deflecting the light signal from the first input port 120 to a certain first output port 121, and the phase grating formed by the last 600 pixels is used for selectively deflecting the light signal from the second input port 130 to a certain second output port 131. The light spot centers of the regions corresponding to the first 600 pixels and the last 600 pixels are determined respectively, and the phase of the pixel points is compensated by the respective corresponding light spot centers.

[0098] In one embodiment, the acquisition of the first light spot center of the pixel points on the first region and the acquisition of the second light spot center of the pixel points on the second region, as shown in FIG. 9, include:

[0099] In step 121, the second theoretical insertion loss reduced by the first output port 121 when the light signal of the first input port 120 is blocked by half is calculated, and the third theoretical insertion loss reduced by the second output port 131 when the light signal of the second input port 130 is blocked by half is calculated.

[0100] The second theoretical insertion loss and the third theoretical insertion loss can be 6dB.

[0101] In step 122, the phase of the pixel points is set to 0 from the first pixel point, and the phases of the other pixel points are the initial phases, and the second actual insertion loss of the first output port is monitored. When the phase of the nth1 pixel point is set to 0, the second actual insertion loss is equal to the second theoretical insertion loss, and the position region of the nth1 pixel point is the first light spot center.

[0102] The first light spot center X center1 = n1.

[0103] In step 123, the phase of the pixel points is set to 0 from the m1+1th pixel point, and the phases of the other pixel points are the initial phases, and the third actual insertion loss of the second output port is monitored. When the phase of the nth2 pixel point is set to 0, the third actual insertion loss is equal to the third theoretical insertion loss, and the position region of the nth2 pixel point is the second light spot center.

[0104] The second light spot center X center2 = n2.

[0105] Referring to FIG. 10, in an embodiment, the first light spot center X center1 and the second light spot center X center2 are shown as an example, wherein the position corresponding to the 211th pixel point is the first light spot center X center1 , and the position corresponding to the 841th pixel point is the second light spot center X center2 .

[0106] After obtaining the position of the light spot center, the phase modulation amount to be superimposed on each pixel point is calculated according to the position of the light spot center, and the phase modulation amount to be superimposed on each pixel point is calculated according to the following formula

[0107] wherein x is the position of the pixel point, x center is the position of the light spot center, λ is the wavelength of the light, f is the focal length of the lens, and d is the pixel size.

[0108] In an embodiment, the focal length of the lens is determined in the following manner: a small lens is arranged in front of the LCOS chip, so that the focal point of the small lens coincides with the light spot center, and the focal length of the lens is the focal length of the small lens; after the focal length of the lens is determined, the small lens is removed. In this process, first, the focal length of the small lens 5 in FIG. 3 is obtained, and the phase compensation amount of each pixel point is determined according to the focal length of the small lens 5, and the small lens 5 is replaced by a method of superimposing the phase modulation amount on the initial phase of each pixel point, so as to avoid increasing the elements.

[0109] Therefore, in the above step 2, the phase modulation amount to be superimposed is calculated according to the position of the light spot center, as shown in FIG. 11, which specifically includes:

[0110] In step 201, the focusing lens 2 and the LCOS chip 3 are arranged in sequence, a small lens 5 is arranged between the focusing lens 2 and the LCOS chip 3, the focal point of the small lens 5 is coincided with the light spot center, and the focal length of the small lens 5 is obtained.

[0111] In actual application scenarios, the small lens 5 is removed after measuring the focal length thereof, and in actual products, the small lens 5 does not exist, and the main purpose of the small lens 5 is to calculate the final phase modulation amount by using the focal length of the small lens 5.

[0112] In step 202, the position of each pixel point, the position of the light spot center, the focal length of the small lens 5, and the wavelength of the light are obtained.

[0113] In step 203, the phase modulation amount of each pixel is obtained based on the position of the pixel, the position of the center of the light spot, the focal length of the small lens 5, and the wavelength of the light.

[0114] Specifically, the position x of the pixel and the position x of the center of the light spot cen t er The formula for obtaining the phase modulation amount of each pixel point based on the lens focal length f, pixel size d, and light wavelength λ of the small lens 5 is as follows:

[0115] When the first fiber array collimator 12 and the second fiber array collimator 13 are provided, the formula for the phase modulation amount of the pixels in the first region is: The formula for the phase modulation amount of the pixels in the second region is: The phase modulation amount of the pixels in the first region is combined with the phase modulation amount of the pixels in the second region to obtain the phase modulation amount used to simultaneously modulate the first region and the second region.

[0116] As mentioned in the aforementioned scheme, superimposing a phase modulation amount on the initial phase of the phase grating can achieve the effect of placing a lens in the wavelength selective switch to focus the optical signal. In one embodiment, the initial optical field of the incident light is E0, and the expression of the optical field after passing through the lens is... in This represents the amount of phase modulation of the light by the lens. When the WSS incident light is switched to a specific output port, the initial phase of the LCOS chip is... Therefore, the light field expression after the incident light passes through the lens and then the LCOS chip 3 is: The aforementioned plan has already been described. The calculation method, based on the above formula, will be explained below. The calculation method.

[0117] In step 3, the method further includes obtaining the initial phase of each pixel. The calculation method for the initial phase, as shown in Figure 12, includes:

[0118] In step 301, the position of the pixel and the number of pixels in a grating period are obtained.

[0119] The phase grating includes multiple grating periods, and one grating period includes multiple pixels.

[0120] In step 302, the initial phase is obtained by multiplying the position of the pixel by 2π and then dividing by the number of pixels in one grating period.

[0121] In the calculation of the initial phase, the formula of the initial phase is derived by the following method, as shown in FIG. 13, which includes:

[0122] In step 311, the diffraction angle of the phase grating, the length of the pixel point, the position of the pixel point and the wavelength of the light are obtained.

[0123] In step 312, the initial phase is calculated according to the diffraction angle of the phase grating, the length of the pixel point, the position of the pixel point and the wavelength of the light.

[0124] In the above formula of the initial phase, the calculation method of the diffraction angle of the phase grating is shown in FIG. 14, which specifically includes:

[0125] In step 321, the length of the pixel point and the number of pixel points in a phase grating period are obtained.

[0126] In step 322, the length of a phase grating period is obtained according to the length of the pixel point and the number of pixel points in the phase grating period.

[0127] In step 323, the diffraction order of the input light signal and the wavelength of the light are obtained.

[0128] In step 324, the diffraction angle of the phase grating is obtained according to the diffraction order of the light signal, the wavelength of the light and the length of the phase grating period.

[0129] In actual application scenarios, according to the diffraction order m of the light signal, the wavelength λ of the light and the length D of the grating period, the calculation formula of the diffraction angle of the phase grating is D·sinθ=mλ. The light entering the output port of the WSS module is generally the +1 order light of diffraction, so m can be set to 1. Of course, in special scenarios, m can be determined according to actual conditions. In the formula of the initial phase provided in the embodiment, the diffraction order m used in the calculation of the diffraction angle θ is 1.

[0130] Suppose that a grating period includes n pixel points, the length of the pixel point is d, and the length of the grating period D is equal to n×d. Therefore, the formula for calculating the initial phase according to the diffraction angle θ of the phase grating, the length d of the pixel point, the position x of the pixel point and the wavelength λ of the light is

[0131] By using the scheme provided by the embodiment of the present application, Fig. 15 is an initial phase diagram of the LCOS chip 3 in an embodiment, Fig. 16 is an output port insertion loss and adjacent port crosstalk diagram before modulation, after superimposing the phase modulation amount as shown in Fig. 17, the phase of each pixel point is as shown in Fig. 18, and the output port insertion loss and adjacent port crosstalk are as shown in Fig. 19, it can be seen that the insertion loss and adjacent port crosstalk are well improved.

[0132] For the wavelength selective switch of the Twin structure, as shown in Fig. 20, it is an initial phase diagram of the LCOS chip 3, after superimposing the phase modulation amount as shown in Fig. 21 and Fig. 22 on the two modules respectively, the phase modulation amount added by the two modules as shown in Fig. 21 and Fig. 22 is combined to obtain the phase modulation amount for simultaneously modulating the two modules as shown in Fig. 23. As shown in Fig. 24, it is an optimized phase diagram after superimposing the phase modulation amount, and according to this compensation mode, the insertion loss and adjacent port crosstalk can be improved.

[0133] The above only describes the preferred embodiments of the present application and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of crosstalk suppression for a wavelength selective switch, characterized by, The method comprises the following steps: acquiring the light spot center of the incident light on a plurality of pixel points on the LCOS chip; calculating the phase modulation amount to be superimposed on each pixel point according to the position of the light spot center; superimposing the phase modulation amount on the initial phase of the pixel point.

2. The crosstalk suppression method of a wavelength selective switch according to claim 1, characterized by, The acquisition of the light spot center of the incident light on a plurality of pixel points on the LCOS chip comprises the following steps: calculating the first theoretical insertion loss of the output port when the incident light is blocked by half; setting the phase of the first pixel point on the LCOS chip to 0, and setting the phase of the other pixel points to the initial phase, and monitoring the first actual insertion loss of the output port; when the phase of the nth pixel point is set to 0, the first actual insertion loss is equal to the first theoretical insertion loss, and the position region of the nth pixel point is the light spot center.

3. The crosstalk suppression method of a wavelength selective switch according to claim 1, wherein, When the wavelength selection switch is a Twin structure wavelength selection switch, the wavelength selection switch comprises a first fiber array collimator and a second fiber array collimator, the first fiber array collimator comprises a first input port and a plurality of first output ports, the second fiber array collimator comprises a second input port and a plurality of second output ports, the first input port corresponds to the first output port, and the second input port corresponds to the second output port, and the acquisition of the light spot center of the incident light on a plurality of pixel points on the LCOS chip comprises the following steps: dividing the plurality of pixel points into a first part and a second part to divide the LCOS chip into a first region and a second region, the first region corresponds to the first input port and the first output port, and the second region corresponds to the second input port and the second output port; wherein the total number of pixel points is M, the first region corresponds to 1 to m1 pixel points, and the second region corresponds to (m1+1) to M pixel points; acquiring the first light spot center of the pixel points in the first region and the second light spot center of the pixel points in the second region, so as to calculate the phase modulation amount of the pixel points in the first region according to the position of the first light spot center and calculate the phase modulation amount of the pixel points in the second region according to the position of the second light spot center.

4. The crosstalk suppression method of a wavelength selective switch according to claim 3, wherein The acquisition of the first light spot center of the pixel points in the first region and the second light spot center of the pixel points in the second region comprises the following steps: calculating the second theoretical insertion loss of the first output port when the optical signal of the first input port is blocked by half; and calculating the third theoretical insertion loss of the second output port when the optical signal of the second input port is blocked by half; setting the phase of the first pixel point to 0, and setting the phase of the other pixel points to the initial phase, and monitoring the second actual insertion loss of the first output port; when the phase of the nth pixel point is set to 0, the second actual insertion loss is equal to the second theoretical insertion loss, and the position region of the nth pixel point is the first light spot center; Set the phase of the pixel point as 0 from the m1+1th pixel point in sequence, and the phase of other pixel points is the initial phase, monitor the third actual insertion loss of the second output port, when the phase of the n2th pixel point is set as 0, the third actual insertion loss is equal to the third theoretical insertion loss, and the position area of the n2th pixel point is the second light spot center.

5. The crosstalk suppression method of a wavelength selective switch according to claim 1, wherein The method comprises the following steps of: Arranging the focusing lens (2) and the LCOS chip (3) in sequence, placing a small lens (5) between the focusing lens (2) and the LCOS chip (3), aligning the focal point of the small lens (5) with the light spot center, and obtaining the focal length of the small lens (5); Obtaining the position of each pixel point, the position of the light spot center, the focal length of the small lens (5) and the wavelength of light; According to the position of the pixel point, the position of the light spot center, the focal length of the small lens (5) and the wavelength of light, the phase modulation amount of each pixel point is obtained.

6. The crosstalk suppression method of a wavelength selective switch according to claim 1, wherein, The method comprises the following steps of: The phase modulation amount superimposed on each of the pixel points is calculated according to the following formula where x is the position of the pixel point, x center is the position of the light spot center, λ is the wavelength of light, f is the focal length of the lens, and d is the pixel size.

7. The crosstalk suppression method of a wavelength selective switch according to claim 6, wherein, The determination method of the lens focal length is as follows: A small lens is arranged before the LCOS chip, the focal point of the small lens is aligned with the light spot center, and the lens focal length is the focal length of the small lens; after the lens focal length is determined, the small lens is removed.

8. The method of crosstalk suppression in a wavelength selective switch according to any of claims 1-7, characterized by, Further comprising obtaining the initial phase of each pixel point, and the calculation method of the initial phase comprises the following steps of: Obtaining the position of the pixel point and the number of pixel points in a grating period; The initial phase is obtained by multiplying the position of the pixel point by 2π and then dividing by the number of pixel points in a grating period.

9. The method of crosstalk suppression in a wavelength selective switch according to any of claims 1-7, characterized by, Further comprising obtaining the initial phase of each pixel point, and the calculation method of the initial phase comprises the following steps of: Obtaining the diffraction angle of the phase grating, the length of the pixel point, the position of the pixel point and the wavelength of light; The initial phase is obtained according to the diffraction angle of the phase grating, the length of the pixel point, the position of the pixel point and the wavelength of light.

10. The crosstalk suppression method of a wavelength selective switch according to claim 9, wherein, The calculation method of the diffraction angle of the phase grating comprises the following steps of: Obtaining the length of the pixel point and the number of pixel points in a grating period; According to the length of the pixel point and the number of pixel points in a grating period, the length of a period of the phase grating is obtained; Obtaining the diffraction order of the input light signal and the wavelength of light; According to the diffraction order of the light signal, the wavelength of light and the length of a period of the phase grating, the diffraction angle of the phase grating is obtained.

11. A wavelength selective switch, characterized by, Comprise: The fiber array collimator (1), the focusing lens (2), the LCOS chip (3) and the driving circuit (4); the focusing lens (2) is arranged between the fiber array collimator (1) and the LCOS chip (3); The fiber array collimator (1) comprises an input port (10) and a plurality of output ports (11), the input port (10) is used for outputting the collimated light signal, and the output port (11) is used for outputting the light signal deflected by the LCOS chip (3); The fiber array collimator (1) comprises an input port (10) and a plurality of output ports (11), the input port (10) is used for outputting the collimated light signal, and the output port (11) is used for outputting the light signal deflected by the LCOS chip (3); The driving circuit (4) is used for adjusting the phase of each pixel point on the LCOS chip (3) according to the crosstalk suppression method of the wavelength selective switch as claimed in any one of claims 1-10.

12. The wavelength selective switch of claim 11, wherein, The number of the fiber array collimators (1) is 2, specifically including a first fiber array collimator (12) and a second fiber array collimator (13), the first fiber array collimator (12) includes a first input port (120) and a plurality of first output ports (121), the second fiber array collimator (13) includes a second input port (130) and a plurality of second output ports (131), the first fiber array collimator (12) and the second fiber array collimator (13) share one LCOS chip (3); The wavelength selective switch further includes a first lens (20) and a second lens (21), the first lens (20) is arranged between the first fiber array collimator (12) and the LCOS chip (3), and the second lens (21) is arranged between the second fiber array collimator (13) and the LCOS chip (3).

13. The wavelength selective switch of claim 11, wherein, The fiber array collimator (1) includes a fiber array and a plurality of collimating lenses, a plurality of fibers in the fiber array are one-to-one coupled with a plurality of the collimating lenses.

14. The wavelength selective switch of claim 11, wherein, The driving circuit (4) is used for loading different voltages on different pixel points of the LCOS chip (3), and different voltages correspond to different phase modulation amounts.

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