Novel wavelength selective switch

Abstract

The utility model discloses a novel wavelength selection switch, which relates to the technical field of all-optical communication and comprises an optical fiber collimation array, a Fourier lens, a 4f imaging system, a diffraction grating, an LCOS (Liquid Crystal On Silicon) device and an MEMS (Micro Electro Mechanical System) device which are sequentially arranged along the direction of an optical path. According to the utility model, by utilizing the fine modulation and deflection characteristics of the LCOS device to the light beam and combining the wide-angle scanning characteristic of the MEMS device, the wavelength selective switch capable of greatly increasing the number of output ports is provided, the reconfigurable optical add-drop multiplexing function is realized, the miniaturization and standardization of the WSS module are realized, and the optical communication technology is high in efficiency and wide in universality.

Description

Technical Field

[0001] This utility model relates to the field of all-optical communication technology, specifically a novel wavelength selection switch. Background Technology

[0002] In recent years, with the exponential growth of optical communication data services, reconfigurable all-optical add-drop multiplexers (ROADMs) have become an important subsystem in optical network nodes, enabling the configuration and exchange of large-capacity information through interconnection between multiple ports. Wavelength selective switches are currently the core component for building ROADM subsystems, featuring high port count, high integration, wide spectrum coverage, and flexible grids.

[0003] Currently, mainstream WSS technology uses silicon-based liquid crystal devices (LCDs) to achieve port switching and bandwidth allocation. They are typically arranged in a 1×N configuration with one input port and multiple output ports, with the N output ports arranged at equal intervals in a certain direction. Existing wavelength selective switches based on phase-type LCOS use diffraction gratings to split light along the wavelength dimension, and then spatially output different wavelength light signals to the target port by loading computational holograms, blazed gratings, etc., onto the LCOS device. However, LCOS itself uses the principle of diffraction to deflect the beam. Due to the limitation of pixel size (greater than 5 micrometers), the resulting first-order diffraction angle is relatively small. Furthermore, to avoid crosstalk, there are certain distance requirements between adjacent ports, resulting in a current limit of no more than 32 ports per WSS. However, compared to the ever-increasing volume of communication service data, the number of ports in existing WSS structures is generally too small, and this structure is gradually failing to meet the needs of reconfigurable optical networks. At the same time, due to the special nature of liquid crystal modulation, LCOS devices have certain requirements on the polarization direction of the incident light, resulting in a large overall optical path volume and low efficiency, limiting its application in ROADM and optical networks.

[0004] Therefore, the problem we need to solve is how to integrate more ports on WSS based on existing LCOS devices, improve the efficiency of optical switches, reduce crosstalk, and at the same time reduce the number of optical path components, so as to realize the miniaturization and standardization of WSS modules and make them suitable for various ROADM and optical network equipment.

[0005] In view of the above, this application is hereby submitted. Utility Model Content

[0006] The purpose of this invention is to provide a novel wavelength selective switch to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, this utility model provides a novel wavelength selective switch, comprising: an optical fiber collimating array, a Fourier lens, a 4f imaging system, a diffraction grating, an LCOS device, and a MEMS device arranged sequentially along the optical path direction.

[0008] Furthermore, the fiber collimation array is located on the front focal plane of the Fourier lens and serves as the input and output ports of the WSS. Its input port is located at the center, and the output ports are distributed around the input port in a two-dimensional matrix arrangement.

[0009] Furthermore, the fiber collimation array includes a microlens array, which is used to collimate the incident beam.

[0010] Furthermore, the 4f imaging system includes a first lens and a second lens, and the ratio of the focal lengths of the first lens and the second lens is used to adjust the size of the light spot illuminating the surface of the LCOS device.

[0011] Furthermore, the diffraction grating is located on the back focal plane of the first lens in the 4f imaging system and is a transmission device. The diffraction grating includes one-dimensional or two-dimensional layouts, which redistribute the incident light in angular space according to the wavelength.

[0012] Furthermore, the LCOS device uses a driving circuit and pixel electrodes on a silicon-based backplane to control the deflection of liquid crystal molecules, thereby changing the phase of the incident light. The LCOS device is insensitive to the polarization of the incident light. A quarter-wave plate or an equivalent quarter-wave plate composed of metamaterials is provided on the silicon-based backplane. To achieve the polarization insensitivity effect, the LCOS device is divided into two regions of equal size, which modulate incident light with different polarizations respectively.

[0013] Furthermore, the LCOS device is located on the imaging surface of the 4f imaging system, and the silicon-based backplane of the LCOS device is fixed parallel to the surface of the MEMS device. In order to reduce the load on the MEMS and increase the scanning frequency and durability, the LCOS device can be directly integrated on the surface of the MEMS device through microfabrication. The MEMS device can be set to a one-dimensional or two-dimensional deflection mode, with a maximum deflection angle of ±20°.

[0014] Compared with the prior art, the beneficial effects of this utility model are:

[0015] 1. This utility model proposes a wavelength selective switch that organically combines LCOS and MEMS devices, which can cover more output ports and reduce crosstalk between ports while ensuring flexible bandwidth.

[0016] 2. This utility model redesigns the LCOS device by using a silicon-based backplane or optical path to make it insensitive to the deflection of incident light, thereby reducing unnecessary polarization control components in the WSS optical path.

[0017] 3. This utility model utilizes an algorithm to optimize the problem of LCOS phase modulation depth deviation caused by large-angle incident light. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the optical path in the vertical direction of a wavelength selective switch based on LCOS and MEMS devices.

[0019] Figure 2 This is a schematic diagram of the horizontal optical path of a wavelength selective switch based on LCOS and MEMS devices.

[0020] Figure 3 This is a schematic diagram of the light spot illuminating the LCOS device after dispersion by a one-dimensional diffraction grating.

[0021] Figure 4 A schematic diagram illustrating how MEMS devices can be used to increase the deflection angle to cover the vertical direction of multi-port output;

[0022] Figure 5 A schematic diagram illustrating how MEMS devices can be used to increase the deflection angle to cover the horizontal direction of multi-port output;

[0023] Figure 6 This is a schematic diagram of the light spot illuminating the LCOS device after dispersion by a two-dimensional diffraction grating.

[0024] Figure 7 A schematic diagram illustrating a method for achieving polarization-independent modulation by adding a quarter-wave plate to an LCOS silicon-based backplane;

[0025] Figure 8 To utilize the optical path to project beams of different polarizations onto different regions of the LCOS device for simultaneous modulation.

[0026] In the figure: 100, fiber collimating array; 110, Fourier lens; 120, 4f imaging system; 1201, first lens; 1202, second lens; 130, diffraction grating; 140, LCOS device; 150, MEMS device; 1601, quarter wave plate; 1701, mirror; 1702, quarter wave plate; 1703, polarization beam splitter. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] Please see Figures 1-8This utility model provides a technical solution: a novel wavelength selective switch, comprising: an optical fiber collimating array 100, a Fourier lens 110, a 4f imaging system 120, a diffraction grating 130, an LCOS device 140, and a MEMS device 150 arranged sequentially along the optical path direction.

[0029] The fiber collimation array 100 is located on the front focal plane of the Fourier lens 110 and serves as the input and output ports of the WSS. Its input port is located at the center, and the output ports are distributed around the input port in a two-dimensional matrix arrangement.

[0030] The fiber collimation array 100 includes a microlens array, which is used to collimate the incident beam.

[0031] The 4f imaging system 120 includes a first lens 1201 and a second lens 1202. The ratio of the focal lengths of the first lens 1201 and the second lens 1202 is used to adjust the size of the light spot illuminating the surface of the LCOS device 140.

[0032] The diffraction grating 130 is located on the back focal plane of the first lens 1201 in the 4f imaging system 120. It is a transmission device. The diffraction grating 130 includes one-dimensional or two-dimensional layouts, which redistribute the incident light in angular space according to the wavelength.

[0033] The LCOS device 140 uses a driving circuit and pixel electrodes on a silicon-based backplane to control the deflection of liquid crystal molecules, thereby changing the phase of the incident light. The LCOS device 140 is insensitive to the polarization of the incident light. A quarter-wave plate 1601 or an equivalent quarter-wave plate 1601 composed of metamaterials is provided on the silicon-based backplane. To achieve the polarization insensitivity effect, the LCOS device 140 is divided into two regions of equal size, which modulate the incident light with different polarizations respectively.

[0034] The LCOS device 140 is located on the imaging surface of the 4f imaging system 120. The silicon-based backplane of the LCOS device 140 is fixed parallel to the surface of the MEMS device 150. In order to reduce the load on the MEMS and increase the scanning frequency and durability, the LCOS device 140 can be directly integrated onto the surface of the MEMS device 150 by micromachining. The MEMS device 150 can be set to a one-dimensional or two-dimensional deflection mode, with a maximum deflection angle of ±20°.

[0035] Fourier lens 110 converts the blazed grating hologram loaded on the LCOS device 140 into a displacement of the light beam along the port alignment direction, ensuring that the light beam can be incident perpendicularly to the output port, thus guaranteeing coupling efficiency. The incident signal beam passes through the input port and is collimated, then sequentially passes through Fourier lens 110 and the first lens 1201 in the 4f imaging system 120, and is focused onto the diffraction grating 130. The diffraction grating 130 generates a dispersion effect, distributing light of different wavelengths to different angles. The light then passes through the second lens 1202 in the 4f imaging system 120 and illuminates different areas of the LCOS device 140 surface, ensuring that the reflected beam of the LCOS can follow the same path in the dispersion direction. Return; A hologram of a blazed grating is loaded onto the LCOS device 140 to perform phase modulation on the incident light spot, thereby achieving diffraction deflection of the beam in a two-dimensional direction, thus controlling the deflection direction of the outgoing light. The beam emitted from the LCOS device 140 passes through the 4f imaging system 120 and the diffraction grating 130 again, and illuminates the Fourier lens 110. After passing through the Fourier lens 110, it returns to different output ports. To achieve a larger deflection angle, the angle deflection of the MEMS device 150 drives the deflection of the LCOS device 140. At the same time, the algorithm is used to optimize the problem of modulation depth deviation of the LCOS device 140 caused by oblique incidence, thereby covering more output ports with the outgoing light.

[0036] Example 1:

[0037] like Figure 1 and Figure 2 As shown, this invention comprises a two-dimensional fiber collimation array 100, a Fourier lens 110, a 4f imaging system 120, a diffraction grating 130, an LCOS device 140, and a MEMS device 150 arranged sequentially along the optical path. The fiber collimation array 100 is located on the front focal plane of the Fourier lens 110 and serves as the input and output ports of the WSS. The input ports are located at the center, and the output ports are distributed around the input ports in a two-dimensional matrix arrangement (m×n, where m and n are both odd numbers). That is, there are m ports in the horizontal direction and n ports in the vertical direction. The fiber collimation array 100 includes a microlens array, which is used to collimate the incident beam.

[0038] The 4F imaging system 120 includes a first lens 1201 and a second lens 1202. The two lenses can be either circular or cylindrical lenses, and their focal length ratio is used to adjust the size and shape of the light spot illuminating the surface of the LCOS device 140. In this embodiment, the first lens 1201 and the second lens 1202 have equal focal lengths.

[0039] The diffraction grating 130 is located on the back focal plane of the first lens 1201 and is a transmission-type device. In this embodiment, the diffraction grating 130 is arranged in one dimension along the vertical direction, with a linewidth of 1201 lines / mm. Figure 1 As shown, the diffraction grating 130 redistributes the incident light in angular space according to the wavelength and illuminates different areas of the LCOS device 140 surface through the second lens 1202, thereby achieving light splitting. The LCOS device 140 is a phase-type device, and the deflection of liquid crystal molecules is controlled by the driving circuit and the pixel electrodes on the silicon-based backplane, thereby changing the phase of the incident light. The pixel size of the LCOS device 140 is 6.8μm, and the effective area has 4096×2400 pixels.

[0040] like Figure 3 As shown, holograms of blazed gratings are loaded at different positions on the LCOS device 140 to phase modulate the incident light spot. The single-wavelength signal is deflected along the vertical direction and returns to the target port along the original optical path, realizing the diffraction deflection of the beam in the two-dimensional direction, thereby controlling the deflection direction of the outgoing light. The beam emitted from the LCOS device 140 passes through the 4f imaging system 120 and the diffraction grating 130 again and illuminates the Fourier lens 110. After passing through the Fourier lens 110, it returns to the corresponding target output port in the fiber collimation array 100. The Fourier lens 110 converts the blazed grating hologram loaded on the LCOS device 140 into the displacement of the beam along the port arrangement direction, ensuring that the beam can be incident perpendicularly to the output port and ensuring coupling efficiency.

[0041] The WSS optical path design in the above embodiment ensures dynamic allocation of the output signal ports in the vertical direction. Since adjacent fiber ports are fixed, to reduce crosstalk between ports, the period of the blazed grating loaded on the LCOS should be as small as possible to achieve a larger deflection angle and cover more ports. However, the pixel size on the LCOS device 140 is fixed, and reducing the period of the blazed grating will reduce diffraction efficiency. The LCOS device 140 is located on the imaging plane of the 4f imaging system 120, and the silicon-based backplane of the LCOS is fixed parallel to the surface of the MEMS device 150. To reduce the load on the MEMS and increase the scanning frequency and durability, the LCOS device 140 can be directly integrated onto the surface of the MEMS device 150 using microfabrication methods. The MEMS device 150 can be configured in a one-dimensional or two-dimensional deflection mode, with a maximum deflection angle of ±20°. Figure 4As shown, to achieve a larger deflection angle, the angle deflection of the MEMS device 150 drives the LCOS device 140 to deflect in the X direction, thereby enabling the output signal to reach ports farther from the center input fiber and increasing the number of effective ports of the WSS. Simultaneously, since oblique incidence causes a deviation in the phase modulation depth of the LCOS device 140, a holographic algorithm is needed to optimize the low diffraction efficiency caused by large-angle incidence, thereby covering more output ports with the emitted light.

[0042] In the above embodiments, the WSS still operates by allocating output ports in a one-dimensional vertical direction, such as... Figure 5 As shown, the deflection of the MEMS device 150 can drive the LCOS device 140 to deflect in the Y direction, thereby realizing signal output on a two-dimensional plane and significantly increasing the number of output ports. It should also be noted that the beam deflection in the WSS is not limited to the port direction; the LCOS device 140 can also be used to deflect the beam in a wavelength direction orthogonal to it. This operating mode, combined with the two-dimensional deflection of the MEMS device 150, can achieve more port allocation modes.

[0043] Example 2:

[0044] To increase the number of WSS ports, the diffraction grating 130 can be replaced from one-dimensional to two-dimensional, so that the light irradiated onto the surface of the LCOS device 140 due to the dispersion effect is distributed in two dimensions, such as... Figure 4 As shown. In this way, a blazed grating loaded solely by the LCOS can be distributed across two-dimensional ports. Similarly, to achieve a larger deflection angle, the MEMS device 150 drives the LCOS device 140 to deflect in both the X and Y directions, thus covering a greater number of ports. It should be noted that different operating modes require optimization of the hologram and the driving of the LCOS and MEMS device 050 to achieve optimal results.

[0045] Since the LCOS device 140 modulates the phase of the light beam by the deflection of liquid crystal molecules, the device itself is inherently polarization-sensitive. Modulation can only occur when the polarization direction of the incident light is parallel to the long axis of the liquid crystal molecules. To make the LCOS device 140 insensitive to the polarization of the incident light, such as... Figure 7 As shown, a quarter-wave plate or an equivalent quarter-wave plate 1601 composed of metamaterial structures can be provided on the silicon-based backplane of the LCOS. However, adding a quarter-wave plate halves the phase modulation depth of the liquid crystal. To achieve the same phase modulation effect, the thickness of the LCOS device 140 itself needs to be increased, which brings difficulties to the manufacturing process. Another device that achieves polarization insensitivity is... Figure 8As shown, it consists of a mirror 1701, a quarter-wave plate 1702, a polarizing beam splitter 1703, and an LCOS device 140. The LCOS device 140 is divided into two equal-sized regions, which modulate incident light with different polarizations respectively. Due to the orthogonal polarization characteristic, this structure can be used to increase the number of ports of the WSS.

[0046] In summary, this invention utilizes the fine modulation and deflection characteristics of the LCOS device 140 and the large-angle scanning characteristics of the MEMS device 150 to propose a wavelength selection switch that significantly increases the number of output ports. This enables reconfigurable optical add-drop multiplexing while simultaneously miniaturizing the WSS module and simplifying the optical path. It is a highly efficient and widely applicable optical communication technology.

[0047] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the present invention itself. Various changes in form and detail may be made to the present invention without departing from the spirit and scope of the appended claims.

Claims

1. A novel wavelength selective switch, characterized in that, include: Along the optical path, a fiber collimating array (100), a Fourier lens (110), a 4f imaging system (120), a diffraction grating (130), an LCOS device (140), and a MEMS device (150) are arranged sequentially.

2. The novel wavelength selective switch as described in claim 1, characterized in that: The fiber collimation array (100) is located on the front focal plane of the Fourier lens (110) and serves as the input and output ports of the WSS. Its input port is located at the center, and the output ports are distributed around the input port in a two-dimensional matrix arrangement.

3. A novel wavelength selective switch as described in claim 2, characterized in that: The fiber collimation array (100) includes a microlens array used to collimate the incident beam.

4. A novel wavelength selective switch as described in claim 1, characterized in that: The 4f imaging system (120) includes a first lens (1201) and a second lens (1202), and the ratio of the focal lengths of the first lens (1201) and the second lens (1202) is used to adjust the size of the light spot illuminating the surface of the LCOS device (140).

5. A novel wavelength selective switch as described in claim 4, characterized in that: The diffraction grating (130) is located on the back focal plane of the first lens (1201) in the 4f imaging system (120) and is a transmission device. The diffraction grating (130) includes one-dimensional or two-dimensional layouts, which redistribute the incident light in angular space according to the wavelength.

6. A novel wavelength selective switch as described in claim 1, characterized in that: The LCOS device (140) controls the deflection of liquid crystal molecules by a driving circuit and pixel electrodes on a silicon-based backplane, thereby changing the phase of the incident light. The LCOS device (140) is insensitive to the polarization of the incident light. A 1 / 4 wave plate (1601) or an equivalent 1 / 4 wave plate (1601) composed of metamaterials is provided on the silicon-based backplane. To achieve the polarization insensitivity effect, the LCOS device (140) is divided into two regions of equal size, which modulate the incident light with different polarizations respectively.

7. A novel wavelength selective switch as described in claim 1, characterized in that: The LCOS device (140) is located on the imaging surface of the 4f imaging system (120). The silicon-based backplane of the LCOS device (140) is fixed parallel to the surface of the MEMS device (150). In order to reduce the load on the MEMS and increase the scanning frequency and durability, the LCOS device (140) can be directly integrated on the surface of the MEMS device by micromachining. The MEMS device (150) can be set to a one-dimensional or two-dimensional deflection mode, with a maximum deflection angle of ±20°.

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