Integrated waveguide mems optical switch and nxn array using mechanical bistable beams

Abstract

This invention discloses an integrated waveguide MEMS optical switch and its N×N array using a mechanical bistable beam. It includes a substrate and optical and mechanical structures placed on the substrate. The optical structure comprises three movable optical couplers and an input-output waveguide group. Both the movable optical couplers and the input-output waveguide group are suspended above the substrate. The movable optical coupler group is connected to an electrostatic comb driver via a transmission rod. Starting from the end connected to the movable optical coupler group, the transmission rod sequentially connects to a first fixed island beam structure, the electrostatic comb driver, and a second fixed island beam structure. The switch structure of this invention has significant advantages such as a large bandwidth range, low insertion loss, low crosstalk, high extinction ratio, simple fabrication process, low processing cost, low power consumption, and strong scalability.

Description

Technical Field

[0001] This invention relates to a MEMS optical switch and optical array in the field of integrated optoelectronic devices, and in particular to an integrated waveguide MEMS optical switch and N×N array using a mechanical bistable beam. Background Technology

[0002] In recent years, the emergence of cloud computing and data-intensive computing has spurred a rapid expansion in the scale of data center networks. The explosive growth in data volume has placed further demands on low-latency, low-power, and reconfigurable networks. Compared with traditional electrical interconnect technologies, optical interconnect technologies have significant advantages in terms of latency and power consumption, making optical interconnects crucial in the construction of large-scale data centers.

[0003] Large-scale optical switch arrays, as core devices of reconfigurable optical networks, greatly enhance the flexibility of optical networks. Currently, numerous optical switch structures have been proposed and attracted extensive research, including integrated waveguide optical switches based on Mach-Zehnder interferometers (MZI), integrated waveguide optical switches based on microring resonators (MRR), free-space optical switches based on micromechanical systems (MEMS), and integrated waveguide optical switches based on MEMS.

[0004] Among numerous optical switch structures, MEMS-based free-space optical switches have attracted widespread attention due to their low loss, high reliability, and strong scalability. Currently, most optical switches in data center networks are free-space MEMS optical switches. For free-space MEMS optical switches, the optical signal propagates and switches in free space after entering the switch from the optical fiber, and is then received by the output optical fiber. Its scalability is excellent, and it can currently achieve hundreds of ports while maintaining low insertion loss and low crosstalk. However, free-space MEMS optical switches have a relatively long switching time due to the inability of free-space MEMS to achieve higher mechanical action speeds; their switching speed is generally in the range of a few milliseconds to tens of milliseconds, which significantly limits the reconfiguration speed of large-scale data centers. Integrated waveguide MEMS optical switches can solve this problem. The integrated waveguide MEMS structure can achieve a smaller mechanical structure size, thereby improving the switching speed. In an integrated waveguide MEMS optical switch, the optical signal is confined within the integrated waveguide after entering the chip from the input optical fiber, and the switching of the optical path is achieved through the integrated waveguide structure and mechanical structure. In recent years, MEMS-based integrated waveguide optical switches have begun to emerge. Compatible with CMOS processes, they enable sub-microsecond fast switching times, low insertion loss, low crosstalk, and a large number of ports. MEMS-based integrated waveguide optical switches hold promise for overcoming the current limitations of optical switch arrays and enabling their application in large-scale optical interconnect networks.

[0005] Non-volatility has been proven to be an effective means of reducing the static power consumption of devices. However, existing MEMS-based integrated waveguide optical switches often lack non-volatility, requiring a high drive voltage to be maintained in the ON state, resulting in high static power consumption. Existing non-volatile MEMS optical switches achieve this by applying prestress to a movable silicon waveguide, which displaces the waveguide out of the plane upon release to form a mechanically bistable state. However, the fabrication process for this type of optical switch is complex, and the double-layer silicon substrate used is incompatible with common silicon photonics processes. Summary of the Invention

[0006] To address the problems existing in the background art, the present invention aims to provide an integrated waveguide MEMS optical switch and N×N array using a mechanical bistable beam. This switch applies a driving voltage to a fixed electrostatic comb, causing it to attract an attractive force with a suspended movable electrostatic comb, which in turn moves the movable electrostatic comb. This movement is further driven by a transmission rod to move a movable optical coupler, thereby changing the waveguide spacing of the optical coupler. The optical signal is coupled between the two waveguides to achieve the purpose of switching the optical path. The mechanical bistable beam is also switched via the transmission rod to provide non-volatility.

[0007] The technical solution of this invention is as follows:

[0008] The switch includes a substrate and optical and mechanical structures placed on the substrate; wherein the optical structure includes a movable optical coupler group and an input-output waveguide group, both of which are suspended above the substrate and are connected to each other;

[0009] The mechanical structure includes a fixed stop mechanism, two fixed island beam arrays, an electrostatic comb driver, and a transmission rod. The movable optical coupler group is fixedly connected to the electrostatic comb driver via the transmission rod. The fixed stop mechanism is located between the movable optical coupler group and the transmission rod. The transmission rod connects the first fixed island beam array, the electrostatic comb driver, and the second fixed island beam array sequentially from the end connected to the movable optical coupler group.

[0010] The movable optical coupler group includes three movable optical couplers. Each movable optical coupler mainly consists of an inner waveguide segment and an outer waveguide segment parallel to the inner waveguide segment. The outer waveguide segment is located outside the inner waveguide segment. The three inner waveguide segments are connected to form an inverted U-shaped waveguide with one side open and the other three sides closed. The open end of the inverted U-shaped waveguide is connected to the transmission rod.

[0011] The input-output waveguide group includes a first input single-mode waveguide, a second input single-mode waveguide, a first output single-mode waveguide, and a second output single-mode waveguide. The two ends of the outer waveguide segment away from the transmission rod are respectively connected to the first input single-mode waveguide and the first output single-mode waveguide. The two outer waveguide segments located on both sides of the transmission rod are respectively connected to the second input single-mode waveguide and the second output single-mode waveguide. The first input single-mode waveguide is distributed close to the second input single-mode waveguide, and the first output single-mode waveguide is distributed close to the second output single-mode waveguide.

[0012] The electrostatic comb driver mainly consists of a fixed electrostatic comb and a movable electrostatic comb. The fixed electrostatic comb is fixed to the base, and the movable electrostatic comb is suspended from the base. The comb teeth of the fixed electrostatic comb and the movable electrostatic comb are arranged opposite to each other and are staggered. The open end of the inverted U-shaped waveguide is fixedly connected to the movable electrostatic comb through a transmission rod.

[0013] The fixed island beam array is mainly formed by several fixed island beam structures arranged at intervals along the length direction of the transmission rod. Each fixed island beam structure is set along the length direction perpendicular to the transmission rod, and two fixed island beam arrays are distributed on both sides of the electrostatic comb driver along the length direction of the transmission rod.

[0014] The fixed island beam structure mainly consists of a mechanically bistable beam group arranged along the length direction perpendicular to the transmission rod and a pair of second fixed islands symmetrically distributed on both sides of the transmission rod. The second fixed islands are fixed to the base, and the mechanically bistable beam group is suspended above the base. The mechanically bistable beam group mainly consists of several mechanically bistable beams arranged at intervals along the length direction of the transmission rod. The two ends of the mechanically bistable beams are connected to the two second fixed islands respectively, and the middle of the mechanically bistable beams is connected to the transmission rod. The length direction of the mechanically bistable beams is perpendicular to the length direction of the transmission rod.

[0015] The fixed stopping mechanism is mainly composed of a first fixed island and a mechanical stopping structure connected together. The first fixed island is fixed to the base and the mechanical stopping structure is suspended from the base. Both the first fixed island and the mechanical stopping structure are located at the opening of the inverted U-shaped waveguide.

[0016] Both the fixed electrostatic comb and the movable electrostatic comb consist of a comb handle and comb teeth periodically distributed on the comb handle. The length direction of the comb handle is perpendicular to the transmission rod, and the length direction of the comb teeth is parallel to the transmission rod. The comb teeth are arranged periodically along the length direction of the comb handle. One end of the comb teeth is connected to the comb handle, and the other end is not connected. The comb teeth of the fixed electrostatic comb and the movable electrostatic comb are distributed in an alternating pattern.

[0017] The shape of a mechanically bistable beam is a trigonometric function shape or other shapes that can form a mechanically bistable state.

[0018] Other shapes that can form a mechanically bistable state include combinations of trigonometric and linear functions, polynomial shapes, or combinations of Boltzmann functions.

[0019] The movable optical coupler is either a directional coupler or a thermally insulating coupler.

[0020] The movable optical coupler, mechanical bistable beam, transmission rod, fixed electrostatic comb, and movable electrostatic comb are made of the same material and have the same thickness.

[0021] The N×N optical switch array includes at least four cascaded integrated waveguide MEMS optical switches.

[0022] The movable optical coupler can be a directional coupler or an adiabatic coupler. There are three movable optical couplers in total: a top optical coupler with a variable waveguide spacing and two left and right optical couplers with a constant waveguide spacing. The outer waveguide segments of the optical couplers are fixed structures, and the three waveguide segments are separated from each other. The inner waveguide segment is a movable structure; the three waveguide segments are connected by a curved waveguide, forming an inverted U-shaped structure and connected to a transmission rod, allowing the relative positions of the inner and outer waveguide segments to be changed under the action of a mechanical structure. All parts of the optical coupler are suspended structures. For the top optical coupler, when the distance between the outer and inner waveguide segments decreases, the coupling between them increases, and light couples from one waveguide segment to another; this is the coupled state. When the distance between the outer and inner waveguide segments increases, there is almost no coupling between them, and the light continues to propagate in the original waveguide; this is the separated state. For the left and right optical couplers, the distance between the inner and outer waveguide segments does not change, and they are always in a coupled state.

[0023] The outer waveguide segments are connected to single-mode waveguides, which serve as input and output ports. Adjacent switching units can be interconnected via single-mode waveguides and waveguide crossovers to form an N×N switching array. The upper outer waveguide segment is connected to single-mode waveguides at both ends, serving as input and output ports, and is referred to as the first input port and the first output port. The lower ends of the left and right outer waveguide segments are connected to single-mode waveguides, serving as input and output ports respectively, and are referred to as the second input port and the second output port; their upper ends are not used as ports.

[0024] The beneficial effects of this invention are:

[0025] 1. Simple materials, simple structure, and low production cost;

[0026] 2. The switch is non-volatile, does not require maintaining the drive voltage, avoids static power consumption, and is not dependent on prestress.

[0027] 3. The switching unit features low insertion loss, low crosstalk, and high extinction ratio over a wide wavelength range;

[0028] 4. The switching unit adopts a capacitor-type driving structure, resulting in extremely low energy consumption.

[0029] 5. The switching unit has two input ports and two output ports. This 2×2 switching unit can be cascaded into a large-scale optical switch array using various topologies, and has strong scalability.

[0030] 6. The switching structure in this invention achieves optical path switching by driving a movable optical coupler with an electrostatic comb to change the waveguide spacing. It obtains non-volatility through a mechanical bistable beam and has significant advantages such as large bandwidth, low insertion loss, low crosstalk, high extinction ratio, simple manufacturing process, low processing cost, low power consumption, and strong scalability. Attached Figure Description

[0031] Figure 1 This is a top view of the structure of the present invention with the top optical coupler in a coupled state (ON);

[0032] Figure 2 yes Figure 1 Cross-sectional view of line A-A';

[0033] Figure 3 yes Figure 1 Cross-sectional view of B-B';

[0034] Figure 4 This is a schematic diagram of an N×N integrated waveguide MEMS optical switch structure based on the Benes topology.

[0035] Figure 5 This is a top view of the present invention with the top optical coupler in the OFF state;

[0036] Figure 6 This is a diagram showing the transmission situation of a fully insulated coupler.

[0037] In the figure: 1. First input single-mode waveguide; 2. Second input single-mode waveguide; 3. First output single-mode waveguide; 4. Second output single-mode waveguide; 5. Inner waveguide segment; 6. Outer waveguide segment; 7. Movable optical coupler; 8.1. First fixed island; 8.2. Second fixed island; 9. Mechanical stopping structure; 10. Transmission rod; 11. Fixed electrostatic comb; 12. Movable electrostatic comb; 13. Mechanical bistable beam; 14. Substrate; 15. Buried layer. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention.

[0039] like Figure 1 and Figure 5As shown, the optical switch includes a substrate 14 and an optical structure and a mechanical structure placed on the substrate 14; wherein the optical structure includes a movable optical coupler group and an input-output waveguide group, both of which are suspended on the substrate 14 and connected to each other by a bent waveguide.

[0040] The mechanical structure includes a fixed stop mechanism, two fixed island beam arrays, an electrostatic comb driver, and a transmission rod 10. The movable optical coupler group is fixedly connected to the electrostatic comb driver via the transmission rod 10. The fixed stop mechanism is located between the movable optical coupler group and the transmission rod 10. The transmission rod 10 connects the first fixed island beam array, the electrostatic comb driver, and the second fixed island beam array sequentially from the end connected to the movable optical coupler group.

[0041] The movable optical coupler group includes three movable optical couplers 7. Each movable optical coupler 7 mainly consists of an inner waveguide segment 5 and an outer waveguide segment 6 parallel to the inner waveguide segment 5. The outer waveguide segment 6 is located outside the inner waveguide segment 5. The three inner waveguide segments 5 are connected by a bent waveguide to form an inverted U-shaped waveguide with one side open and the other three sides closed. The open end of the inverted U-shaped waveguide is connected to the drive rod 10.

[0042] The input-output waveguide group includes a first input single-mode waveguide 1, a second input single-mode waveguide 2, a first output single-mode waveguide 3, and a second output single-mode waveguide 4. The two ends of the outer waveguide segment 6 away from the transmission rod 10 are respectively connected to the first input single-mode waveguide 1 and the first output single-mode waveguide 3. The two outer waveguide segments 6 located on both sides of the transmission rod 10 are respectively connected to the second input single-mode waveguide 2 and the second output single-mode waveguide 4. The first input single-mode waveguide 1 is distributed close to the second input single-mode waveguide 2, and the first output single-mode waveguide 3 is distributed close to the second output single-mode waveguide 4. The first input single-mode waveguide 1, the second input single-mode waveguide 2, the first output single-mode waveguide 3, and the second output single-mode waveguide 4 serve as the first input terminal, the second input terminal, the first output terminal, and the second output terminal of the optical switch, respectively.

[0043] The inner waveguide segment 5 is either the first inner waveguide segment, the second inner waveguide segment, or the third inner waveguide segment, and the outer waveguide segment 6 is either the first outer waveguide segment, the second outer waveguide segment, or the third outer waveguide segment. Specifically, the inverted U-shaped waveguide mainly consists of a first inner waveguide segment, a second inner waveguide segment, and a third inner waveguide segment connected to both ends of the first inner waveguide segment and perpendicular to the length direction of the first inner waveguide segment. The first inner waveguide segment faces the opening of the inverted U-shaped waveguide, and the two ends of the inverted U-shaped waveguide are connected to the second inner waveguide segment and the third inner waveguide segment, respectively. The first outer waveguide segment, the second outer waveguide segment, and the third outer waveguide segment are parallel to the first inner waveguide segment, the second inner waveguide segment, and the third inner waveguide segment, respectively. The two ends of the first outer waveguide segment are connected to the first input single-mode waveguide 1 and the first output single-mode waveguide 3, respectively. The second outer waveguide segment and the third outer waveguide segment are connected to the second input single-mode waveguide 2 and the second output single-mode waveguide 4, respectively.

[0044] The electrostatic comb driver mainly consists of a fixed electrostatic comb 11 and a movable electrostatic comb 12. The fixed electrostatic comb 11 is fixed to the base 14, and the movable electrostatic comb 12 is suspended above the base 14. The comb teeth of the fixed electrostatic comb 11 and the movable electrostatic comb 12 are arranged opposite to each other and are staggered. The open end of the inverted U-shaped waveguide is fixedly connected to the movable electrostatic comb 12 through the transmission rod 10.

[0045] The fixed island beam array is mainly formed by several fixed island beam structures arranged at intervals along the length direction of the transmission rod 10. Each fixed island beam structure is set along the length direction perpendicular to the transmission rod 10, and two fixed island beam arrays are distributed on both sides of the electrostatic comb driver along the length direction of the transmission rod 10.

[0046] The fixed island beam structure mainly consists of a mechanically bistable beam group arranged along the length direction perpendicular to the transmission rod 10 and a pair of second fixed islands 8.1 symmetrically distributed on both sides of the transmission rod 10 along the comb tooth direction. The second fixed islands 8.1 are fixed to the base 14, and the mechanically bistable beam group is suspended above the base 14. The mechanically bistable beam group mainly consists of several mechanically bistable beams 13 arranged at intervals along the length direction of the transmission rod 10. The two ends of the mechanically bistable beams 13 are connected to the two second fixed islands 8.1 respectively, and the middle of the mechanically bistable beams 13 is connected to the transmission rod 10. The length direction of the mechanically bistable beams 13 is perpendicular to the length direction of the transmission rod 10.

[0047] The fixed stop mechanism is mainly composed of a first fixed island 8.1 and a mechanical stop structure 9 connected together. The first fixed island 8.1 is fixed to the base 14 and the mechanical stop structure 9 is suspended in the base 14. The first fixed island 8.1 and the mechanical stop structure 9 are located at the opening of the inverted U-shaped waveguide. That is, the fixed stop mechanism is located between the inverted U-shaped waveguide and the transmission rod 10. The fixed stop mechanism is used to limit the movement of the transmission rod 10 in its own length direction.

[0048] The mechanical structure may also include a fixed stop assembly. The fixed stop assembly and the fixed stop mechanism have the same composition and are symmetrically distributed. Both are composed of the first fixed island 8.1 and the mechanical stop structure 9 connected together. The transmission rod 10 may also be located between the fixed stop mechanism and the fixed stop assembly.

[0049] The mechanical stopping structure 9 is a conical structure connected to a separate first fixed island 8.1. It can be distributed at the top and bottom of the transmission rod 10 to limit the range of motion of the transmission rod 10 when the mechanical bistable beam 13 switches states.

[0050] Both the fixed electrostatic comb 11 and the movable electrostatic comb 12 consist of a comb handle and comb teeth periodically distributed on the comb handle. The length direction of the comb handle is perpendicular to the transmission rod 10, and the length direction of the comb teeth is parallel to the transmission rod 10. The comb teeth are periodically arranged along the length direction of the comb handle. One end of the comb teeth is connected to the comb handle, and the other end is not connected. The comb teeth of the fixed electrostatic comb 11 and the movable electrostatic comb 12 are distributed in opposite directions and alternately.

[0051] The movable optical coupler 7 is either a directional coupler or a thermally insulating coupler.

[0052] The movable optical coupler 7, the mechanical bistable beam 13, the transmission rod 10, the fixed electrostatic comb 11, and the movable electrostatic comb 12 are made of the same material and have the same thickness. The entire switching unit structure or N×N array can be fabricated using monolithic integrated processing.

[0053] The N×N optical switch array comprises at least four cascaded integrated waveguide MEMS optical switches.

[0054] An N×N optical switch array should include at least four of the above-mentioned integrated waveguide MEMS optical switch units. Adjacent switch units are connected by single-mode waveguides and waveguide crossovers. The connection method between switch units can adopt, but is not limited to, Benes, Cross-Bar topologies.

[0055] The vertical rod of the transmission rod 10 is connected to the movable electrostatic comb 12 and the mechanical bistable beam 13, and is supported by the second fixed island 8.1 connected to the mechanical bistable beam 13. The electrostatic comb driver drives the inner waveguide segment 5 in the inverted U-shaped waveguide to move along the length of the transmission rod 10, changing the two waveguide spacings in the top movable optical coupler 7, and causing the mechanical bistable beam 13 to undergo elastic deformation and switch to another stable state.

[0056] The movable optical coupler 7 can be a directional coupler or an adiabatic coupler, both of which are suspended structures. The outer waveguide segment 6 is connected to the single-mode waveguides 1, 2, 3, and 4, which serve as input and output ports, and remains stationary. The three inner waveguide segments 5 are connected into an inverted U-shape by bending waveguides and move vertically under the drive of the transmission rod 10. During the movement, the waveguide spacing of the movable optical coupler 7 on the left and right sides remains unchanged, while the waveguide spacing of the movable optical coupler 7 at the top changes. The amount of change is determined by the deformation between the two steady states of the mechanical bistable beam 13. The ends of the outer waveguide segments 6 on the left and right sides that are not used as ports can be connected to additional tapered waveguides to reduce end-face reflections.

[0057] like Figure 1 As shown, the transmission rod 10 has a T-shaped structure, with a horizontal rod at the top. This horizontal rod is perpendicularly connected to the inner waveguide sections 5 of the two movable optical couplers 7 to enhance the mechanical stability of the inverted U-shaped waveguide and reduce waveguide end-face reflection. The vertical rod of the transmission rod 10, starting from the end connected to the movable optical coupler 7, sequentially connects to the first set of mechanically bistable beams, the movable electrostatic comb driver 12, and the second set of mechanically bistable beams from top to bottom. The mechanically bistable beams are a suspended structure, consisting of several mechanically bistable beams 13. The two ends of each mechanically bistable beam 13 are connected to two second fixed islands 8.2, and the transmission rod 1 is connected to the middle of each mechanically bistable beam 13.

[0058] like Figure 2 As shown, the fixed islands 8.1 and 8.2 are square structures, and are connected to the base 14 through the buried layer 15. The mechanical bistable beam 13 is a suspended structure. The second fixed island 8.2 supports the mechanical bistable beam 13. Each second fixed island 8.2 is connected to two mechanical bistable beams 13.

[0059] The mechanically bistable beam 13 can be a beam with a trigonometric function shape or other beam shapes that can form a mechanically bistable state. The mechanically bistable beam 13 has two stable states and can undergo elastic deformation under the action of the transmission rod 10, switching between the two stable states, exhibiting non-volatility. The position of the mechanically bistable beam 13 in the stable state is controlled by pre-design or an additional mechanical stopping structure 9 to determine the relative positions of the inner and outer waveguide segments 5 in the movable optical coupler 7 in the two stable states. Two sets of mechanically bistable beams are used, one above the other, to enhance the mechanical stability of the transmission rod and reduce the out-of-plane deformation of the structure.

[0060] like Figure 1As shown, the fixed electrostatic comb 11 and the movable electrostatic comb 12 have similar structures. Both consist of a comb handle and comb teeth periodically distributed on the comb handle. The electrostatic comb driver includes two pairs of fixed electrostatic combs 11 and one pair of movable electrostatic combs 12. The two pairs of fixed electrostatic combs 11 are distributed on both sides of the movable electrostatic comb 12 along the length of the transmission rod 10. One pair of fixed electrostatic combs 11 is closer to the movable electrostatic comb 12, depending on the current steady state of the mechanical bistable beam 13. After the mechanical bistable beam 13 switches to a steady state, the other pair of fixed electrostatic combs 11 is closer to the movable electrostatic comb 12. The two states are distributed in a mirror-like manner. The side of the fixed electrostatic comb 11 closest to the transmission rod 10 is not connected to the transmission rod 10, while the side furthest from the transmission rod 10 is connected to the external circuit. The comb teeth of the fixed electrostatic comb 11 are distributed on the side closest to the movable electrostatic comb 12. The movable electrostatic comb 12 is a suspended structure, symmetrically distributed on both sides of the vertical direction of the transmission rod 10, located inside the two pairs of fixed electrostatic combs 11. The movable electrostatic comb 12 is connected to the transmission rod 10 on the side closest to the transmission rod 10, and not connected on the side away from the transmission rod 10. The comb teeth of the movable electrostatic comb 12 are distributed on both sides facing the fixed electrostatic combs 11. Figure 3 As shown, the fixed electrostatic comb 11 is supported by a buried layer 15 below the comb handle and is connected to the base 14 through the buried layer 15. Each pair of fixed electrostatic combs 11 is symmetrically distributed on both sides of the transmission rod 10 along the length of the comb handle.

[0061] like Figure 5 As shown, when the electrostatic comb driver is working, a voltage is applied to the fixed electrostatic comb 11 below through an external circuit, creating a potential difference between it and the movable electrostatic comb 12. This potential difference generates an attractive force between the fixed electrostatic comb 11 and the movable electrostatic comb 12. Since the fixed electrostatic comb 11 is connected to the substrate 14 through the buried layer material 15 and is immovable, while the movable electrostatic comb 12 is a suspended and movable structure, the movable electrostatic comb 12 will move closer to the fixed electrostatic comb 11 below. This movement drives the transmission rod 10 to displace parallel to the vertical direction of the transmission rod 10 through the connection between the movable electrostatic comb 12 and the transmission rod 10. Furthermore, the connection between the horizontal rod of the transmission rod 10 and the inverted U-shaped waveguide drives the movable inner waveguide segment 5 to displace parallel to the vertical direction of the transmission rod 10. At the same time, the mechanical bistable beam 13 undergoes elastic deformation under its influence, switching states. When the voltage is removed, the mechanical bistable beam 13 will stabilize in another stable state. When a voltage is applied to the fixed electrostatic comb 11 above, the structure will switch back to its original state based on the same process, such as... Figure 1 As shown.

[0062] like Figure 5As shown, the top movable optical coupler 7 is in the OFF state at this time. The optical signal input from the first input port 1 will be directly output from the first output port 3, and the light input from the second input port 2 will be output from the second output port 4 after passing through the left and right movable optical couplers 7. Figure 1 As shown, when a certain voltage is applied to and removed from the fixed electrostatic comb 11 above, the mechanical bistable beam 13 will switch to another stable state, and the movable optical coupler 7 at the top will become coupled (ON). The optical signal input from the first input port 1 will pass through the movable optical couplers 7 on the top and right sides and be output from the first output port 3. The optical signal input from the second input port 2 will pass through the movable optical couplers 7 on the left and top sides and be output from the second output port 4. When a certain voltage is applied to and removed from the fixed electrostatic comb 11 below, the structure will return to the OFF state. Figure 5 As shown above, this is a complete switching action process.

[0063] like Figure 1 As shown, the MEMS optical switch in this invention has two input ports and two output ports, making it a 2×2 optical switch, which is more scalable than a 1×2 optical switch structure. 1×2 optical switches are generally cascaded in a cross-bar topology to form a large-scale switch array. An N×N array formed using this topology requires as many as N² optical switch units. In contrast, the 2×2 optical switch offers greater flexibility in selecting the topology for large-scale arrays; it can also be cascaded using a Benes topology, such as... Figure 4 As shown, forming an N×N switch array requires only N (log2N-0.5) optical switch units, which significantly reduces the number of switch units required for large-scale switch arrays.

[0064] The following describes specific implementations of the present invention:

[0065] Silicon-on-insulator (SOI) was chosen as the implementation platform, with a 220 nm thick silicon top layer, a 2 μm thick silicon dioxide buried layer 15, and a silicon substrate. The considered wavelength range is 1530 nm to 1565 nm, using TE-polarized optical signals. The optical coupler adopts a fully adiabatic design with a length of 25.4 μm, a wide port width of 400 nm, and a narrow port width of 300 nm. The width variation line shape was optimized using PSO to achieve the highest possible transmittance within the 1530 nm to 1565 nm wavelength range. The mechanically bistable beam 13 adopts a trigonometric function shape, and the deformation between the two steady states results in a waveguide spacing of 150 nm in the coupled state and 950 nm in the decoupled state for the top variable-gap optical coupler.

[0066] The optical performance of the device was simulated and verified using the three-dimensional finite-difference time-domain method (3D-FDTD). In the OFF state, the incident light field input from the first input terminal 1 is almost entirely output from the first output terminal 3, and the incident light field input from the second input terminal 2 is almost entirely output from the second output port 4. The transmission behavior of a single fully adiabatic coupler at this time is as follows: Figure 6 As shown in the upper figure. At this time, a single fully adiabatic coupler can achieve low loss and high extinction ratio in the wavelength range of 1530nm to 1565nm, with a loss between 0dB and 0.05dB and an extinction ratio greater than 40dB. After applying voltage to the fixed electrostatic comb 11 and removing it, the movable electrostatic comb 12 pushes the inverted U-shaped waveguide upward through the transmission rod 10, so that the movable optical coupler enters the coupling state. Under the action of the mechanical bistable beam 13, it is kept in the ON state. The optical signal will be coupled from one waveguide to another. The incident light field input from the first input terminal 1 is almost entirely output from the first output terminal 3, and the incident light field input from the second input terminal 2 is almost entirely output from the second output port 4. At this time, the transmission of a single fully adiabatic coupler is as follows. Figure 6 As shown in the figure below, a single fully adiabatic coupler can achieve low loss and high extinction ratio in the 1530nm to 1565nm wavelength band, with losses ranging from 0.01dB to 0.08dB and extinction ratios ranging from 20.0dB to 38.1dB. Therefore, the MEMS optical switch proposed in this invention can achieve large bandwidth, low loss, high extinction ratio, and low power consumption.

[0067] Experiments have verified that the mechanical bistable beam of the MEMS optical switch proposed in this invention can complete steady-state switching under voltage drive, and the switch is non-volatile.

[0068] The above embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. An integrated waveguide MEMS optical switch using a mechanically bistable beam, characterized in that: It includes a substrate (14) and optical and mechanical structures placed on the substrate (14); wherein the optical structure includes a movable optical coupler group and an input-output waveguide group, both of which are suspended on the substrate (14) and connected to each other; The mechanical structure includes a fixed stop mechanism, two fixed island beam arrays, an electrostatic comb driver, and a transmission rod (10). The movable optical coupler group is fixedly connected to the electrostatic comb driver through the transmission rod (10). The fixed stop mechanism is set between the movable optical coupler group and the transmission rod (10). The transmission rod (10) is connected sequentially from one end connected to the movable optical coupler group to the first fixed island beam array, the electrostatic comb driver, and the second fixed island beam array. The fixed island beam array is formed by several fixed island beam structures arranged at intervals along the length direction of the transmission rod (10). Each fixed island beam structure is set along the length direction perpendicular to the transmission rod (10). Two fixed island beam arrays are distributed on both sides of the electrostatic comb driver along the length direction of the transmission rod (10). The fixed island beam structure consists of a mechanically bistable beam group arranged along the length direction perpendicular to the transmission rod (10) and a pair of second fixed islands (8.2) symmetrically distributed on both sides of the transmission rod (10); the second fixed islands (8.2) are fixed to the base (14) and the mechanically bistable beam group is suspended above the base (14). The mechanically bistable beam group consists of several mechanically bistable beams (13) arranged at intervals along the length direction of the transmission rod (10). The two ends of the mechanically bistable beams (13) are respectively connected to the two second fixed islands (8.2), and the middle of the mechanically bistable beams (13) is connected to the transmission rod (10). The length direction of the mechanically bistable beams (13) is perpendicular to the length direction of the transmission rod (10). The movable optical coupler group includes three movable optical couplers (7), each movable optical coupler (7) consists of an inner waveguide segment (5) and an outer waveguide segment (6) parallel to the inner waveguide segment (5); the outer waveguide segment (6) is located outside the inner waveguide segment (5), and the three inner waveguide segments (5) are connected to form an inverted U-shaped waveguide with one side open and the other three sides closed, and the open end of the inverted U-shaped waveguide is connected to the transmission rod (10); The input-output waveguide group includes a first input single-mode waveguide (1), a second input single-mode waveguide (2), a first output single-mode waveguide (3), and a second output single-mode waveguide (4). The two ends of the outer waveguide segment (6) away from the transmission rod (10) are respectively connected to the first input single-mode waveguide (1) and the first output single-mode waveguide (3). The two outer waveguide segments (6) located on both sides of the transmission rod (10) are respectively connected to the second input single-mode waveguide (2) and the second output single-mode waveguide (4). The first input single-mode waveguide (1) is distributed close to the second input single-mode waveguide (2), and the first output single-mode waveguide (3) is distributed close to the second output single-mode waveguide (4).

2. The integrated waveguide MEMS optical switch using a mechanical bistable beam according to claim 1, characterized in that: The electrostatic comb driver consists of a fixed electrostatic comb (11) and a movable electrostatic comb (12). The fixed electrostatic comb (11) is fixed to the base (14) and the movable electrostatic comb (12) is suspended above the base (14). The comb teeth of the fixed electrostatic comb (11) and the movable electrostatic comb (12) are arranged opposite to each other and are staggered. The open end of the inverted U-shaped waveguide is fixedly connected to the movable electrostatic comb (12) through the transmission rod (10).

3. The integrated waveguide MEMS optical switch using a mechanical bistable beam according to claim 1, characterized in that: The fixed stopping mechanism is composed of a first fixed island (8.1) and a mechanical stopping structure (9). The first fixed island (8.1) is fixed to the base (14) and the mechanical stopping structure (9) is suspended above the base (14). Both the first fixed island (8.1) and the mechanical stopping structure (9) are located at the opening of the inverted U-shaped waveguide.

4. The integrated waveguide MEMS optical switch using a mechanical bistable beam according to claim 2, characterized in that: The fixed electrostatic comb (11) and the movable electrostatic comb (12) are both composed of a comb handle and comb teeth periodically distributed on the comb handle. The length direction of the comb handle is perpendicular to the transmission rod (10), and the length direction of the comb teeth is parallel to the transmission rod (10). The comb teeth are periodically arranged along the length direction of the comb handle. One end of the comb teeth is connected to the comb handle, and the other end is not connected. The comb teeth of the fixed electrostatic comb (11) and the movable electrostatic comb (12) are distributed in opposite directions and alternately.

5. The integrated waveguide MEMS optical switch using a mechanical bistable beam according to claim 1, characterized in that: The mechanically bistable beam (13) is in the shape of a trigonometric function or other shapes that can form a mechanically bistable state.

6. The integrated waveguide MEMS optical switch using a mechanical bistable beam according to claim 1, characterized in that: The movable optical coupler (7) is a directional coupler or an adiabatic coupler.

7. The integrated waveguide MEMS optical switch using a mechanical bistable beam according to claim 3, characterized in that: The movable optical coupler (7), mechanical bistable beam (13), transmission rod (10), fixed electrostatic comb (11) and movable electrostatic comb (12) are made of the same material and have the same thickness.

8. An N×N integrated waveguide MEMS optical switch array using a mechanically bistable beam, characterized in that: The N×N optical switch array includes at least four cascaded integrated waveguide MEMS optical switches as described in any one of claims 1 to 7.

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