CN110494781A

CN110494781A - Wavelength selecting method and wavelength-selective switches

Info

Publication number: CN110494781A
Application number: CN201780089423.7A
Authority: CN
Inventors: 王元武; 赵臻青; 苏玉锋; 夏丹青
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2017-04-18
Filing date: 2017-04-18
Publication date: 2019-11-22
Also published as: WO2018191862A1

Abstract

The invention discloses a kind of methods of wavelength selection and wavelength-selective switches WSS, are related to technical field of photo communication.A kind of wavelength-selective switches WSS, including three input light path unit, hot spot deflection unit and output light path unit parts.Wherein, the hot spot deflection unit is used to carry out the deflection of space angle to the multiple single-wavelength light signals exported by the input light path part and is sent to the output light path unit, for controlling the output port position of more single-wavelength light signals.The hot spot deflection unit includes deflection device and control circuit, and the deflection device is made of at least two deflection planes, and the control circuit is used to control the spatial deflection angle for the optical signal for being incident at least two deflection plane.Change the spatial position of hot spot by hot spot deflection unit, so that optical signal can be exported from more output optical fibre ports, improves the port number of WSS.In addition, hot spot deflection unit, which passes through, changes facula position to increase the spacing between hot spot, so that WSS has the ability for improving channels crosstalk.

Description

Wavelength selection method and wavelength selection switch

Technical Field

The embodiment of the invention relates to the field of optical communication, in particular to a wavelength selection method and a wavelength selection switch.

Background

Optical networks, for example: a Wavelength Division Multiplexing (Wavelength Division Multiplexing, WDM) network usually adopts a static path configuration method as one of the most commonly used service carrying networks of operators. With the increasing capacity and dynamic performance of network services, it is obvious that the static path configuration method cannot meet the requirements of service development, and the configuration requirements of operators on dynamic service paths are more and more strong.

Reconfigurable Optical Add/Drop Multiplexer (ROADM for short) is a key device for supporting an Optical network to realize dynamic service path configuration, supports the up/down/blocking of any wavelength service, can realize the arbitrary expansion of communication service through software remote control, and has great flexibility. The Wavelength Selective Switch (WSS) is a core sub-device constituting the ROADM, and can implement transmission and switching of any Wavelength in multiple directions. The number of ports of the WSS determines the number of directional dimensions for optical signal transmission and switching. As the networking architecture of ROADM nodes continues to evolve, WSSs are also evolving towards higher port numbers in order to meet the more directional optical wavelength switching. In addition to this, crosstalk characteristics such as: channel crosstalk is also one of the important characteristics that measure WSS.

There are various technologies for implementing WSS, and currently, a mainstream manner is to use Liquid Crystal On Silicon (LCOS). LCOS technology can provide finer frequency resolution and also has advantages over other prior art in performance metrics. LCOS technology realizes the spatial deflection of the optical path by controlling the phase change of the optical path, and the deflection angle directly determines the port number of the WSS. However, the driving technique has a limit deflection angle on the premise of ensuring a certain diffraction efficiency. This means that there is also an upper limit to the number of ports that can be achieved, typically a maximum of 30.

An improved method for providing the number of ports is currently provided, which increases the total number of optical signals that can be processed by the WSS by using a plurality of layers of diffraction gratings, corresponding to a certain number of input and output ports, respectively, thereby increasing the number of ports of the WSS. However, the method has high device complexity and high implementation cost, and the solution does not consider the crosstalk problem of the WSS at all.

Disclosure of Invention

Embodiments of the present invention describe a method and apparatus for wavelength selection (WSS) to increase the number of output ports and provide the ability to improve channel crosstalk.

In one aspect, an embodiment of the present invention provides a wavelength selective switch WSS, where the WSS includes a diffraction grating, a light spot deflection unit, an LCOS spatial light modulator, and an output array, where:

the diffraction grating is configured to perform spatial demultiplexing on a first optical signal and output a plurality of second optical signals, where the first optical signal includes a plurality of wavelengths, and the second optical signal is a single-wavelength optical signal;

the light spot deflection unit is configured to deflect the plurality of second optical signals by a preset spatial deflection angle so as to change a spatial position where the plurality of second optical signals are incident on the LCOS spatial light modulator, where preset spatial deflection angles of at least two second optical signals in the plurality of second optical signals are different;

the LCOS spatial light modulator is used for performing spatial angle deflection on the plurality of second optical signals deflected by the light spot deflection unit so as to enable the plurality of second optical signals to be output to a preset output port of the output array;

the output array comprises a plurality of output ports, and is used for collimating and outputting the plurality of second optical signals after the spatial angle deflection received from the LCOS spatial light modulator.

In one possible design, the spot deflection unit comprises a deflection device and a control circuit for controlling the angle of spatial angular deflection of the optical signal incident on the deflection device. Specifically, the deflection device is a Liquid Crystal On Silicon (LCOS), a reflector group or a micro-electro-mechanical system (MEMS) rotating mirror group. It should be noted that the deflecting device includes at least two deflecting surfaces, and the two deflecting surfaces are used for deflecting the incident optical signal by the same or different spatial angles.

In one possible design, the spot deflection unit comprises at least two deflection devices, which are arranged in a plurality of layers. The design can further improve the capability of spatial angle deflection of the deflection unit, thereby further improving the port number of the WSS and enhancing the capability of the WSS to improve port crosstalk.

In a possible design, the spot deflection unit comprises at least two deflection devices, which are arranged in cascade. Optionally, a lens is further included between the at least two deflecting devices, and the lens is configured to collimate and focus the plurality of second optical signals. The design can further improve the capability of spatial angle deflection of the deflection unit, thereby further improving the port number of the WSS and enhancing the capability of the WSS to improve port crosstalk.

In another aspect, an embodiment of the present invention provides a wavelength selective switch WSS, including: an input array, a polarization controller, a lens, a diffraction grating, a shaping system, a spot deflection device (also known as a deflection device), an LCOS spatial light modulator, and an output array, wherein:

the input array is used for carrying out input collimation on one or more multi-wavelength optical signals; the one or more multi-wavelength signals are subsequently referred to simply as first optical signals;

the diffraction grating is used for carrying out spatial demultiplexing on the first optical signal and outputting a plurality of single-wavelength optical signals; the plurality of single-wavelength signals are subsequently referred to as second optical signals for short;

the light spot deflection device is used for deflecting the second optical signal by a preset spatial angle so as to change the spatial position of the second optical signal incident to the LCOS spatial light modulator;

the LCOS spatial light modulator is used for performing spatial angle deflection on the second optical signal deflected by the light spot deflection device so as to enable the second optical signal to be output from a preset output port;

the polarization controller is used for carrying out polarization state processing on the first optical signal passing through the input array, and specifically is used for converting a random polarization state and a linear polarization state; the second optical signal is further used for carrying out polarization processing on the second optical signal output by the lens;

the lens is used for collimating and focusing the first optical signal output by the polarization controller; further for collimating and focusing the second optical signal output via the diffraction grating;

the shaping system is used for shaping the second optical signal output by the diffraction grating; further for shaping said second optical signal output via said LCOS spatial light modulator;

the diffraction grating is further configured to spatially multiplex the second optical signal output via the shaping system;

the output array comprises a plurality of output ports for collimating and outputting the second optical signal output by the polarization controller.

It should be noted that, the above apparatus is to place the polarization controller after the input array and before the output array; the polarization controller may also be placed before the input array, after the output array.

In a possible design, the spot deflection unit comprises at least two deflection devices, which are arranged in cascade. Optionally, a lens is further included between the at least two deflecting devices, and the lens is configured to collimate and focus the second optical signal. The design can further improve the capability of spatial angle deflection of the deflection unit, thereby further improving the port number of the WSS and enhancing the capability of the WSS to improve port crosstalk.

In one possible design, the WSS further includes a mirror for folding the second optical signal, for example: optical path overlap is prevented from occurring via the second optical signal output via the LCOS spatial light modulator.

In one possible design, the polarization controller includes a first polarization controller and a second polarization controller for switching the random polarization state and the linear polarization state of the optical signal, respectively.

In one possible design, the diffraction gratings include a first diffraction grating and a second diffraction grating for spatially multiplexing and demultiplexing optical signals, respectively.

In one possible design, the shaping system includes a first shaping system and a second shaping system, each for shaping the optical signal.

In yet another aspect, an embodiment of the present invention provides a method for selecting a wavelength, where the method includes:

the method comprises the steps that spatial demultiplexing is carried out on a first optical signal through a diffraction grating, and a plurality of second optical signals are output, wherein the first optical signal comprises a plurality of wavelengths, and the second optical signals are single-wavelength optical signals;

the second optical signals are deflected by preset space angles through a light spot deflection unit so as to change the space positions of the second optical signals which are incident to the LCOS spatial light modulator, wherein the preset space deflection angles of at least two second optical signals in the second optical signals are different;

performing, by an LCOS spatial light modulator, spatial angle deflection on the plurality of second optical signals deflected by the light spot deflection unit, so that the plurality of second optical signals are output from output ports preset in an output array;

and outputting the plurality of second optical signals after the spatial angle deflection received from the LCOS spatial light modulator in a collimation mode through an output array.

Compared with the prior art, the scheme provided by the invention realizes deflection of different optical signals by a certain spatial angle through the light spot deflection unit, so that the optical signals can be output to more output ports, and the number of the output ports of the WSS is increased at a simpler cost. In addition, the invention provides a scheme that the distance between optical signals can be increased through the deflection unit, so that the WSS has the capability of improving channel crosstalk.

Drawings

Embodiments of the invention will now be described in more detail with reference to the accompanying drawings, in which:

fig. 1 is a schematic view of a possible application scenario of a WSS according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of one possible configuration of the ROADM node shown in FIG. 1;

FIG. 3a is a schematic diagram of the functional module composition of the WSS;

FIG. 3b is a diagram illustrating a possible related parameter for calculating the number of ports according to the prior art;

FIG. 3c is a diagram illustrating a possible channel crosstalk calculation-related parameter;

FIG. 4 is a schematic diagram of a possible WSS function module according to an embodiment of the present invention;

FIG. 5a is a schematic diagram of a possible WSS structure provided by the embodiment of the present invention;

fig. 5b is a schematic diagram of the distribution of the light spots 1 shown in fig. 5 a;

fig. 5c is a schematic diagram of the distribution of the light spots 2 shown in fig. 5 a;

fig. 6 is a schematic diagram of related parameters for calculating a possible port number according to an embodiment of the present invention;

FIG. 7 is a schematic diagram illustrating an increase in the number of ports according to an embodiment of the present invention;

FIG. 8a is a schematic diagram of another possible WSS structure provided by an embodiment of the present invention;

fig. 8b is a schematic diagram of the distribution of the light spots 1 shown in fig. 8 a;

fig. 8c is a schematic diagram of the distribution of the light spots 2 shown in fig. 8 a;

FIG. 9a is a schematic diagram of another possible WSS structure provided by the embodiment of the present invention;

fig. 9b is a schematic diagram of the distribution of the light spots 1 shown in fig. 9 a;

fig. 9c is a schematic diagram of the distribution of the light spots 2 shown in fig. 9 a;

fig. 9d is a schematic diagram of the distribution of the light spots 3 shown in fig. 9 a;

FIG. 10 is a simplified block diagram of a possible WSS according to an embodiment of the present invention;

fig. 11 is a flowchart of a possible wavelength selection method according to an embodiment of the present invention.

In the different figures, the same reference numerals indicate identical features or devices which are at least functionally identical.

Detailed Description

The application scenario described in the embodiment of the present invention is to more clearly illustrate the technical solution of the embodiment of the present invention, and does not form a limitation on the technical solution provided in the embodiment of the present invention, and as a person having ordinary skill in the art knows that along with the evolution of a network architecture and the appearance of a new service scenario, the technical solution provided in the embodiment of the present invention is also applicable to similar technical problems.

Fig. 1 is a schematic diagram of an application scenario of a possible WSS according to an embodiment of the present invention. Fig. 1 shows an example of a ring optical network, which is composed of 4 ROADM nodes, that is, NE1, NE2, NE3, and NE 4. Each node supports local up-down or pass-through of wavelengths. The WSS is used as an important core sub-device of a ROADM node and is used for selecting any wavelength signal from any input multi-wavelength signal and outputting the wavelength signal to any one or more of N output ports in a combined mode. In addition, the WSS may also combine signals from the N input ports and output the combined signals to one or more output ports. Since the optical path is reversible, a WSS of 1 × N can also be used as a WSS of N × 1.

As an example, fig. 2 shows a schematic diagram of a possible structure of the ROADM node (e.g., NE4) shown in fig. 1. As shown, the ROADM node includes two WSSs, two receivers, and two transmitters, among other sub-devices. Two WSSs are dimensions 1 × N and N × 1 (N ═ 3 in this example), respectively, that is, one WSS receives an optical signal containing 16 wavelengths from one input port thereof and splits it into three paths: one path (including wavelength lambda)₂，λ₃，…,λ₁₅) The signal is directly transmitted through the node and is output after being multiplexed by another WSS; the other two paths (respectively containing lambda)₁And λ₁₆) Down the node through the receivers (i.e., receiver 2 and receiver 1); the other WSS receives different optical signals from 3 input interfaces and outputs the optical signals through one output interface, namely one path (including wavelength lambda)₂，λ₃，…,λ₁₅) Directly from another WSS; the other two paths (respectively containing wavelength lambda)₁And λ₁₆) Uploaded at the node by the sender (i.e., sender 1 and sender 2). The embodiment of the invention does not limit how the specific WSSs are combined and used to form the ROADM node. Furthermore, it will be understood by those skilled in the art that the ROADM may contain other sub-devices such as optical amplifiers, wavelength converters, etc. in addition to the components shown in fig. 1b, according to specific needs. For simplicity of description, the following embodiments all take a single-input multi-output (i.e. 1 × N) WSS as an example, but in practice, the embodiments of the present invention are also applicable to other types of WSSs, for example: WSS of N × 1 and WSS of N × M.

ROADMs have the capability of dynamically selecting wavelengths and can be implemented by remotely configuring WSS modules thereof through software. Specifically, as shown in fig. 3a, the existing WSS module may be simply divided into two blocks, i.e., a processing unit and an optical device unit, and an interactive interface is provided to the outside, so as to output the feedback signal of the WSS module and the external control signal. The processing unit is used for processing an input signal and controlling parameters of a part of optical devices (for example, controlling a voltage of the spatial light modulator so as to change an output port of some wavelength signals), and may include Field Programmable Gate Arrays (FPGAs), Random Access Memories (RAMs), Read Only Memories (ROMs) and LCOS spatial light modulator control circuits (or controllers), Analog-to-Digital converters (ADCs), and other components.

The performance indexes of the WSS device comprise port number, channel crosstalk, port crosstalk, device volume and the like. Wherein the invention mainly relates to port number and channel stringTwo performance parameters are perturbed. Specifically, taking the spatial light modulator as LCOS as an example, at present, the number N of ports of the WSS is_pCan be calculated by the following formula:

N_p＝(tanθ)*L/Δ；

where θ is a spatial deflection angle (sometimes referred to as a diffraction angle or a diffraction angle) of a light beam on the LCOS spatial light modulator, tan is a tangent function operation on θ, L is a distance (unit: millimeter (mm)) from the diffraction grating to the LCOS spatial light modulator, and Δ is a pitch of an arrangement of the output port (WSS of 1 × N) or the input port (WSS of N × 1) optical fibers. As an example, reference may be made to θ and L identified in the simplified equivalent optical path diagram shown in fig. 3 b. It is worth noting that the number of ports N_pAccording to the difference of specific design and manufacturing technology of the WSS, the calculation can be carried out in other modes, but the current different calculation modes have the common characteristics that: the number of ports is proportional to the diffraction angle and the distance between the diffraction grating and the spatial light modulator, i.e. the number of ports can be increased by increasing θ or L. However, due to device process limitations of spatial light modulators and volume (or size) requirements of WSS, both of these parameters are subject to a range of limitations.

Similarly, taking the spot as a circular spot as an example, the channel crosstalk R of the WSS can be calculated by the following formula:

R＝10log{exp[-(W/R)²]}

where W is the separation of two spots and R is the spot radius, see the example of fig. 3 c. It is worth noting that depending on the specific design and fabrication technique of the WSS, the optical spot may have different characteristics, such as: different spot shapes (oval, circular or rectangular, etc.) and therefore channel cross-talk can also be calculated in other ways for a particular spot characteristic. However, different calculation methods have a common characteristic that: the channel crosstalk between two light spots is inversely proportional to the distance between the two light spots, i.e. the channel crosstalk, especially the channel crosstalk between two adjacent light spots, can be reduced by increasing the distance between the light spots.

Fig. 4 is a schematic diagram of a possible WSS functional module according to an embodiment of the present invention. Specifically, the WSS includes three parts, i.e., an input optical path unit 301, a spot deflecting unit 302, and an output optical path unit 303. The spot deflection unit 302 includes a control unit 302a (sometimes also referred to as a control circuit) including at least two deflection surfaces, and a deflection device 302b (sometimes also referred to as a deflection unit) for controlling a spatial deflection angle of an optical signal incident on the at least two deflection surfaces. It should be noted that the control unit may reuse the resources (e.g., memory, FPGA resources, etc.) of the existing processing unit shown in fig. 3a or implement the functions of the existing processing unit shown in fig. 3a by extending the existing processing unit. The control circuit can control the spatial deflection angle of the deflection unit by acquiring an external control signal, and can also output some feedback signals if necessary.

Specifically, the deflection may be realized by a reflection type device or a diffraction type device, and the specific method used in the embodiment of the present invention is not limited in any way. The optical spot deflecting unit is configured to deflect the multiple single-wavelength optical signals output by the input optical path unit 301 by a preset spatial angle and send the multiple single-wavelength optical signals to the output optical path portion. The preset spatial angle of different optical signals is deflected through the light spot deflection unit, and the WSS can change the relative position of the light spots of the optical device in the output optical path unit (for example, the distance between the light spots is increased, and for example, the incidence range of the light spots is changed), so that the WSS has the capability of improving channel crosstalk and/or port number.

The embodiments of the present invention will be described in further detail below based on the common aspects related to the embodiments of the present invention described above. The optical fibers in the embodiments described below are either single mode or multimode fibers, unless otherwise specified, and the invention is not limited in any way to the type of fiber specifically used.

Example 1

Fig. 5a is a schematic diagram of a possible WSS structure according to an embodiment of the present invention. It is worth noting that fig. 5a only contains the optics portion of the WSS, and the control unit is omitted and not shown, but will be mentioned as needed in the detailed description.

In fig. 5a, a section 301, i.e. an input optical path unit, includes an input array 3011, a first polarization controller 3012, a first lens 3013, a first diffraction grating 3014, and a first shaping system 3015. Wherein the position of the first polarization controller 3012 may vary. The first polarization controller 3012 may also precede the input array in the input optical path unit. Specifically, the first polarization controller 3012 may be a slide type polarization controller, or may be another type of polarization controller, such as a fiber polarization controller.

The input array 3011 is configured to collimate and input optical signals (for example, optical signals with 80 wavelengths in a C-band, and for example, optical signals with 16 wavelengths in an L-band, in this embodiment, 5 wavelengths are taken as an example) input to the WSS apparatus. In a 1 × N WSS, the input array 3011 may be 1 fiber, as shown in fig. 5a as I (1); in a WSS of N × 1 or N × N, the input array 3011 may be N optical fibers arranged in a manner, such as: the equal spacing is arranged in a straight line or a rectangle according to a certain plane distance. The first polarization controller 3012 is configured to perform polarization processing on the optical signal output by the input array, and convert the optical signal from randomly polarized light to linearly polarized light. The first lens 3013 is used to focus and collimate the optical signal, but does not change its spatial relative position. The first diffraction grating 3014 is configured to process optical signals with multiple wavelengths such that the optical signals are spatially separated to obtain multiple optical signals with single wavelength. In short, the first diffraction grating performs spatial demultiplexing on one multi-wavelength signal, thereby obtaining a plurality of single-wavelength optical signals. The first shaping system 3015 is used to shape (also called shaping) the single-wavelength optical signals (5 single-wavelength signals in this embodiment) to a specific shape required by the optical system of the WSS, such as: oval or circular shapes; it is also possible to change the spot size of the optical signal but the first shaping system does not change the pitch of the spots. Specifically, the first shaping system may be a cylindrical mirror, and may also be other optical devices with shaping functions, such as: a lens.

In fig. 5a, part 302a, i.e. the deflection unit 3021 (or deflection device), is used for the spatial angular deflection of the spot input to the unit. Specifically, the specific spatial deflection angle is controlled by the control section shown in fig. 4 sending a control signal to the deflection unit 3021. The deflection unit 3021 may be an LCOS chip (also referred to as LCOS), a mirror assembly, or a MEMS mirror assembly. Taking the deflection unit 3021 as an LCOS chip as an example, the LCOS itself is composed of a plurality of deflection surfaces, so that different light signals incident on the surface of the LCOS can be controlled by different diffraction (or reflection) angles by applying different periodic voltages, thereby realizing the same or different spatial angle deflection for different single-wavelength signals. For another example, when the deflection unit 3021 is a MEMS turning mirror group (i.e., includes a plurality of MEMS turning mirrors), each MEMS turning mirror can be controlled by two driving voltages with different axial directions, so as to implement a certain angle of deflection for optical signals incident on different MEMS turning mirrors.

It should be noted that, in the deflection unit 3021 according to the embodiment of the present invention, there are at least two deflection surfaces, and different deflection surfaces may deflect the optical signal incident to the deflection at the same or different spatial positions of the angle, for example: as shown in fig. 5b and 5c, where λ₁，λ₃And λ₅Angle of deflection is the same, λ₂And λ₄The angle of deflection is the same, but λ₁Heel lambda₄The spatial angles of deflection are different. However, the number relationship of the single-wavelength optical signals incident on the deflection surface is not limited in any way in the embodiments of the present invention, and may be a single-wavelength signal corresponding to one deflection surface, or may be in other forms, for example: a plurality of single wavelength signals corresponding to a single deflection plane, etc. In the present embodiment, assuming that the deflection unit 3021 has 5 deflection surfaces capable of being independently controlled, it is possible to spatially and angularly deflect the spots of 5 single-wavelength signals input to the unit, respectively. As shown in fig. 5b, a schematic view of a spot incident on the deflection unit 3021, i.e. spot 1 in fig. 5 a. Wherein λ is₁，λ₂，λ₃，λ₄And λ₅Numbering the wavelengths corresponding to the 5 light spots; w₁The distance between any two adjacent light spots; r₁Is the radius of any one spot. Fig. 5c shows a schematic diagram of the spot output from the deflection unit 3021, i.e. spot 2 in fig. 5 a. Wherein λ is₁，λ₂，λ₃，λ₄And λ₅Numbering the wavelengths corresponding to the 5 light spots; w₂The distance between any two adjacent light spots; r₁Is the radius of any one spot. As can be seen from fig. 5b and 5c, the deflection unit 3021 does not change the size of the spot (i.e. R in fig. 5b and 5 c)₁Remain unchanged) but change the relative position between the spots. In particular, λ₁，λ₃And λ₅The corresponding light spot is moved by the deflection unit 3021 from the original Y-axis value of 0 to a positive Y-axis value (e.g., 2.5mm (millimeters)); and λ₂And λ₄The corresponding spot is moved by the transmitting unit from the original Y-axis value of 0 to a negative Y-axis value (e.g., -2.5mm (millimeters)). Assuming that the original distance between two adjacent spots is 5mm, the pitch of the two spots via the deflection unit 3021 increases to (approximately) 7.1 mm. As can be seen from the above-mentioned example of the channel crosstalk calculation formula, the WSS achieves the effect of reducing the channel crosstalk between the optical spots (different single-wavelength optical signals) by increasing the inter-optical-spot spacing.

In fig. 5a, part 303, i.e. the output optical path unit, includes an LCOS spatial light modulator 3031, a second shaping system 3032, a second diffraction grating 3033, a second lens 3034, a second polarization controller 3035 and an output array 3036. Wherein the position of the second polarization controller 3035 may be varied. The second polarization controller 3035 may also be after the output array in the output optical path unit. Specifically, the second polarization controller 3035 may be a slide-type polarization controller, or may be another type of polarization controller, such as a fiber polarization controller.

The LCOS spatial light modulator 3031 is configured to perform spatial deflection angle adjustment on the multiple single-wavelength optical signals output by the deflection unit 3021, so that the multiple single-wavelength optical signals can be output from a preset output fiber(s) (i.e., a certain fiber port of the output array). The second shaping system 3032 is used to shape the input optical signal (e.g., 5 single-wavelength optical signals in this embodiment) and adjust the optical signal from a specific shape (e.g., circular or elliptical) back to the shape before being input to the WSS optical system. The second diffraction grating 3033 is used for processing the input optical signal, so that a plurality of wavelength signals output through the same outlet are required to be spatially multiplexed. The second lens 3034 is used for collimating and shaping the output multiple single-wavelength optical signals, but does not change the spatial relative positions thereof. The second polarization controller 3035 is configured to perform polarization processing on the input optical signal, and convert the optical signal from linearly polarized light to randomly polarized light. The output array 3036 is used for output collimation of the optical signals input by the array 3036. In a WSS of 1 × N or N × N, the output array 3036 is N fibers, for example: equally spaced in a line (e.g. O (1), …, O (n) as shown in fig. 5 a) or in a rectangle at a planar distance, etc. Whereas in the WSS of N x 1, the output array 3036 is 1 fiber.

Fig. 6 is a schematic diagram of a possible port number related parameter according to an embodiment of the present invention. Where θ is a deflection angle of the light beam on the LCOS spatial light modulator 3031, L is a distance from the second diffraction grating 3033 to the LCOS spatial light modulator, and D is a maximum value of the light spot deflection unit which can be adjusted by the deflection unit 3021. Since the position of the light spot incident on the LCOS spatial light modulator 3035 is no longer a fixed relative position, but can be adjusted to a certain extent by the light spot deflection unit. Therefore, the calculation formula of the number of WSS ports mentioned earlier in this application is no longer applicable, but the parameters provided according to the embodiment of the present invention are modified as follows:

N_p＝[(tanθ)*L+D]/Δ

for example, assume that θ is 5 degrees, L is 100mm (millimeters), and Δ is 0.25 mm. Number of ports N that can be supported by an existing WSS_pTan5 100/0.25 34. According to the example of fig. 5a, assuming that the deflection range D of the deflection unit for the optical spot is 5mm, the WSS in the embodiment of the present invention can support the number of ports N_p(tan5 × 100+5)/0.25 ═ 54. Therefore, the position of the light spot can be flexibly adjusted by the light spot deflection unit in the embodiment of the invention, and the improvement can be realizedNumber of ports of WSS.

Fig. 7 is a schematic diagram illustrating an increase in the number of ports according to an embodiment of the present invention. It should be noted that, for simplicity of illustration, only some of the critical optical components are included in the figure. The LCOS spatial light modulator 3031 currently outputs one wavelength optical signal from the 34 th port, and the light spot is already at the highest position that the LCOS spatial light modulator 3031 can adjust, and accordingly, the deflection angle (which may also be referred to as diffraction angle) thereof has been adjusted to the maximum (i.e., 5 degrees). At this time, if the wavelength optical signal needs to be output from the 34 th port to the 54 th port, the control unit needs to input a control signal to the deflection angle of the deflection unit 3021, and the corresponding spot position needs to be adjusted by 5 mm. The output from the 34 th port to the 54 th port is realized on the premise of ensuring that the diffraction angle (or deflection angle) of the LCOS spatial light modulator 3031 is constant.

It should be added that, if the diffraction direction of the LCOS spatial light modulator 3031 is the same as the adjustable spatial angle direction of the deflection unit 3021 in the light spot deflection unit, the specific numerical calculation for controlling the input control signal specifically output by the LCOS spatial light modulator 3031 to a certain fiber output port may be implemented by a one-dimensional algorithm. If the diffraction direction of the LCOS spatial light modulator 3031 and the direction in which the deflection unit 3021 in the light spot deflection unit can be adjusted are different directions, for example, the two directions are perpendicular to each other, the numerical calculation of the control signal for controlling the LCOS spatial light modulator 3031 to output to the input of a certain output port can be implemented by a two-dimensional algorithm. No matter what algorithm is used and the latitude number of the specific algorithm, the numerical conversion calculation from the control signal inputted from the outside to the specific control deflection unit can be realized by the control unit such as FPGA shown in fig. 2. The embodiment of the invention does not limit the specific design of the control unit.

Example 2

Fig. 8a is a schematic diagram of another possible WSS structure according to an embodiment of the present invention.

The types and functions of the optical devices included in the

portions

301, 302a, and 303 in fig. 8a are the same as those included in the

portions

301, 302a, and 303 in fig. 5a, and are not described herein again.

The difference is that the portion 301 of the input array 3011 in figure 8a contains two arrays of input fibres and the first diffraction grating 3014 contains a two-layer grating. Correspondingly, the portion 302a includes two deflection units, namely a deflection unit 3021 and a deflection unit 3022, which are arranged in layers, and the portion 303 includes an LCOS spatial light modulator 3031 and a second diffraction grating 3032, which are also two layers. A further difference is that the spot is elliptical rather than circular as shown in figure 5.

In particular, the two input fibers may be used to input optical signals of different wavelength bands, for example, optical signals of C-band and L-band, respectively. Then, the two layers of the first and

second diffraction gratings

3014 and 3033 may spatially demultiplex and spatially multiplex optical signals of two different wavelength bands, respectively. Correspondingly, the two layers of deflection units receive the control signals of the control unit, and can correspondingly adjust the spatial deflection angle of at least two input single-wavelength signals, so that the position of the light spot entering the LCOS spatial light modulator is changed, and finally the light spot is output through different output arrays. In particular, the distribution of the spot 1 given in fig. 8a is shown in fig. 8b, where λ₁，λ₂，λ₃，λ₄And λ₅The wavelength numbers corresponding to 5 light spots of the C wave band are numbered; lambda [ alpha ]_A，λ_B，λ_C，λ_DAnd λ_EThe wavelength numbers corresponding to the 5 light spots of the L wave band are numbered. After the two layers of deflection units, the position of the light spot is changed, and the light spot diagram (i.e. light spot 2) is shown in fig. 8 c. E.g. λ_BThe distance between the light spot and other shifted light spots is increased relative to the wavelength before incidence in the negative direction of the Y axis, so that the channel crosstalk performance can be improved. Also for example, λ_CAfter passing through the deflection unit, the position of the deflection unit is changed to the spot distribution range of the other wave band, so that the number of output ports which can be selected by the deflection unit is increased. Since the position where the light spot (or single wavelength optical signal) is incident on the LCOS spatial light modulator 3031 can be changed, it is possible to change the position of the light spot (or single wavelength optical signal) incident on the LCOS spatial light modulator 3031The range of the fiber outlet ports can be enlarged, namely, the number of ports which can be supported by the WSS is increased. Similarly, by adjusting the position of the spot, i.e. increasing the spot pitch (e.g.: λ of FIG. 8 c)₁And λ₂Is increased from that of fig. 8 b), channel crosstalk of the WSS is reduced.

Example 3

Fig. 9a is a schematic structural diagram of another possible WSS according to an embodiment of the present invention.

The types and functions of the optical devices included in the input optical path unit 301, the deflection unit 302a, and the output optical path unit 303 in fig. 9a are the same as those of the optical devices included in the input optical path unit 301, the deflection unit 302a, and the output optical path unit 303 in fig. 5a, and are not described herein again.

Fig. 9a differs from fig. 5a in that:

1) the output optical path unit 303 of fig. 9a further comprises a mirror 3037 for preventing the optical signals from spatially overlapping; it should be added that: the relative position of the light spot is not changed by the reflector 3037; the position of the reflector can be adjusted according to actual needs, and the embodiment of the invention does not limit the specific position of the reflector;

2) the input optical path portion 301 and the output optical path portion 303 of fig. 9a use the same set of optical components (i.e., the shaping system 3015, the polarization controller 3012, the diffraction grating 3014, and the lens 3013) to achieve different functions, which utilizes the principle of optical path reversibility. For example, in this embodiment, the input optical path portion 301 uses the diffraction grating 3014 to perform spatial demultiplexing on an optical signal containing multiple wavelengths, so that the optical signal of each wavelength can be separately processed, and the output optical path portion 303 uses the same diffraction grating 3014 to perform spatial multiplexing on multiple optical signals of single wavelength, that is, multiple optical signals can be combined and output through the same optical fiber. Doing so may further reduce the number of devices, thereby reducing the volume of the WSS. However, in particular, how to combine the individual multiple wavelengths and output a specific number of optical signal outputs is determined according to specific traffic requirements.

3) The deflection unit 302a of fig. 9a comprises two deflection units, namely a deflection unit 3021 and a deflection unit 3022, arranged in cascade and between which a lens 3023 is placed for collimation and focusing. In a particular application, two or more deflection units may be included. It should be noted that the lens 3023 is an optional optical component.

4) The spot of fig. 9a is oval, rather than circular.

It should be noted that the input portion and the output portion described above share a set of devices to perform the functions of the reciprocal process, which can also be applied to embodiment 2.

Fig. 9b, 9c and 9d show schematic diagrams of spot 1, spot 2 and spot 3 of the present embodiment, where λ₁，λ₂，λ₃，λ₄And λ₅The wavelengths corresponding to the 5 light spots are numbered. Assume that the illustrated spot of fig. 9d is the target spot profile required by the LCOS spatial light modulator 3031. The 5 spots are arranged at equal intervals on the X-axis before entering the deflection unit 3021. After the deflection unit 3021 the relative position of the 5 spots is changed, in particular λ₁，λ₃And λ₅Moving a certain distance, lambda, in the positive direction of the Y axis₂And λ₄And moves a certain distance in the opposite direction of the Y axis. After the deflection unit 3022 the relative position of the 5 spots is further changed, in particular λ₁，λ₃And λ₅Further moved a certain distance, lambda, in the positive direction of the Y axis₂And λ₄Further moved a certain distance in the opposite direction of the Y axis. When each deflection unit has limitation on the space deflection angle acted by an incident light spot and cannot realize the preset space deflection angle of a target light spot through one deflection unit, the light spots are deflected through the cascade connection of a plurality of deflection units.

As can be seen from fig. 9b, 9c and 9d, after passing through two cascaded deflection units, the inter-spot spacing is increased, so that the cross talk between channels can be reduced. In addition, unlike the prior art that the light enters the LCOS spatial phase modulator only through a fixed position, the embodiment of the present invention adjusts the deflection angle of the light spot through the multi-level deflection unit, so that the light spot can change a certain incident range, thereby increasing the outputtable range, i.e., increasing the number of ports.

Example 4

Fig. 10 is a simplified structural diagram of a possible WSS according to an embodiment of the present invention.

Specifically, the WSS includes a diffraction grating 3014, a spot deflection unit 302, an LCOS spatial light modulator 3031, and an output array 3036, wherein:

a diffraction grating 3014 for spatially demultiplexing at least one multi-wavelength optical signal incident to the device, thereby outputting a plurality of single-wavelength optical signals;

a light spot deflection unit 302, configured to perform preset spatial angle deflection on the multiple single-wavelength optical signals, and to change a spatial position where the multiple single-wavelength optical signals are incident on the LCOS spatial light modulator, where preset spatial deflection angles of at least two single-wavelength optical signals in the multiple single-wavelength optical signals are different;

an LCOS spatial light modulator 3031, configured to perform spatial angle deflection on the multiple single-wavelength optical signals deflected by the optical spot deflection unit, so that the multiple single-wavelength optical signals are output from preset output ports of the output array;

the output array 3036 includes a plurality of output ports for collimating and outputting the plurality of single-wavelength optical signals after being deflected from the spatial location received by the LCOS spatial light modulator.

The shape of

spots

1 and 2 shown in fig. 10 can be various, for example: circular, as well as: an oval shape. Taking the light spot as a circle as an example, the description of the

light spots

1 and 2 in fig. 10 is the same as the description of the light spot in fig. 5, and the description thereof is omitted here.

The spot deflection unit includes a deflection device and a control circuit for controlling an angle of spatial angular deflection of an optical signal incident to the deflection device. Specifically, the deflection device is a Liquid Crystal On Silicon (LCOS), a mirror group or a micro-electro-mechanical system (MEMS) rotating mirror group. It should be noted that the deflecting device includes at least two deflecting surfaces, and the two deflecting surfaces are used for deflecting the incident optical signal by the same or different spatial angles.

When the optical spot deflecting unit comprises a plurality of deflecting devices, the plurality of deflecting devices may be arranged in multiple layers or in a cascade arrangement, and such a design may further improve the capability of the deflecting unit to deflect spatially and angularly, thereby further improving the number of ports of the WSS and enhancing the capability of the WSS to improve port crosstalk. Optionally, when the plurality of deflecting devices are arranged in cascade, a lens is further included between every two deflecting devices for collimating and focusing the optical signal.

The position of the light spot is changed through the light spot deflection unit, so that optical signals can be output from more output optical fiber ports, and the number of ports of the WSS is increased. In addition, the spot deflection unit can change the position of the light spots to increase the space between the light spots, so that the WSS has the capability of improving channel crosstalk.

Example 5

Fig. 11 is a flowchart of a possible optical wavelength selection method according to an embodiment of the present invention. The method is used for selecting one or more multi-wavelength optical signals (also called as first optical signals) to output any wavelength signal to a preset output port after the wavelength signal is combined.

S1: at least one multi-wavelength optical signal is subjected to spatial demultiplexing through a diffraction grating, and a plurality of single-wavelength optical signals (also called as second optical signals) are output;

s2: deflecting the second optical signal according to a preset spatial angle through a light spot deflection unit, wherein the light spot deflection unit is used for changing the spatial position of the second optical signal incident to an LCOS (liquid crystal on silicon) spatial light modulator, and the preset spatial deflection angles of at least two single-wavelength optical signals in the multiple single-wavelength optical signals are different;

s3: performing spatial angle deflection on the second optical signal deflected by the light spot deflection unit through an LCOS spatial light modulator, so that the second optical signal is output from an output port preset in an output array;

s4: and outputting the plurality of single-wavelength optical signals after the spatial angle deflection received from the LCOS spatial light modulator in a collimation mode through an output array.

The at least one multi-wavelength optical signal is subjected to an optical device combination process as shown in fig. 5, 8, 9 or 10. Specifically, the optical device through which the multi-wavelength optical signal passes and the action (or function) of the device on the multi-wavelength optical signal refer to the detailed descriptions in the above four embodiments, which are not described herein again.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

A wavelength selective switch WSS, comprising a diffraction grating, a spot deflection unit, a liquid crystal on silicon, LCOS, spatial light modulator, and an output array, wherein:

the diffraction grating is configured to perform spatial demultiplexing on a first optical signal and output a plurality of second optical signals, where the first optical signal includes a plurality of wavelengths, and the second optical signal is a single-wavelength optical signal;

the light spot deflection unit is configured to deflect the plurality of second optical signals by a preset spatial deflection angle so as to change a spatial position where the plurality of second optical signals are incident on the LCOS spatial light modulator, where preset spatial deflection angles of at least two second optical signals in the plurality of second optical signals are different;

the LCOS spatial light modulator is used for performing spatial angle deflection on the plurality of second optical signals deflected by the light spot deflection unit so as to enable the plurality of second optical signals to be output to a preset output port of the output array;

the output array comprises a plurality of output ports, and is used for collimating and outputting the plurality of second optical signals after the spatial angle deflection received from the LCOS spatial light modulator.
The WSS of claim 1, wherein the spot deflection unit includes a deflection device and a control circuit for controlling an angle at which the deflection device spatially and angularly deflects the optical signal incident to the deflection device.
A WSS according to claim 2, the deflection device comprising at least two deflection surfaces for deflecting an incident optical signal by the same or different spatial angles.
A WSS according to claim 2 or 3 wherein the deflection device is a liquid crystal on silicon LCOS, a mirror array or a micro-electromechanical system MEMS mirror array.
A WSS according to any of claims 1 to 4 wherein the spot deflecting unit comprises at least two deflecting devices, the at least two deflecting devices being arranged in a plurality of layers.
A WSS according to any of claims 1 to 4 wherein the spot deflection unit comprises at least two deflection devices, the at least two deflection devices being arranged in cascade.
A WSS according to claim 6 wherein the at least two deflecting devices include a lens therebetween for collimating and focusing the plurality of second optical signals.
A method of wavelength selection, the method comprising:

the method comprises the steps that spatial demultiplexing is carried out on a first optical signal through a diffraction grating, and a plurality of second optical signals are output, wherein the first optical signal comprises a plurality of wavelengths, and the second optical signals are single-wavelength optical signals;

the second optical signals are deflected by preset space angles through a light spot deflection unit so as to change the space positions of the second optical signals which are incident to the LCOS spatial light modulator, wherein the preset space deflection angles of at least two second optical signals in the second optical signals are different;

performing, by an LCOS spatial light modulator, spatial angle deflection on the plurality of second optical signals deflected by the light spot deflection unit, so that the plurality of second optical signals are output from output ports preset in an output array;

and outputting the plurality of second optical signals after the spatial angle deflection received from the LCOS spatial light modulator in a collimation mode through an output array.
The method according to claim 8, wherein the spot deflection unit includes a deflection device and a control circuit for controlling an angle at which the deflection device spatially and angularly deflects the optical signal incident to the deflection device.
The method of claim 9, the deflection device comprising at least two deflection surfaces for deflecting an incident optical signal by the same or different spatial angles.