A driving device and a control method of a liquid crystal modulation type on-chip integrated optical switch

Abstract

This invention relates to a driving device and control method for a liquid crystal modulation type on-chip integrated optical switch. The driving device includes an optical switch network, a first logic switch, a second logic switch, a digital-to-analog converter unit, and a microprocessor. The switching of the liquid crystal layer between a working state and a reset state is controlled by controlling the first electrode, the second electrode, and the second conductive layer within the optical switch unit. The control method involves adjusting the potential difference between the first and second electrodes in the working state to change the orientation of liquid crystal molecules within the liquid crystal layer; and adjusting the potential difference between the first and second electrodes and the second conductive layer in the reset state to rapidly reset the liquid crystal molecules within the liquid crystal layer. By combining the two states of the liquid crystal molecules for real-time control and rapid switching, this invention solves the problem of slow speed at which liquid crystal molecules recover their original vertical orientation state relying solely on elastic force, significantly improving the switching speed and performance of the optical switch.

Description

Technical Field

[0001] This invention relates to the field of optical switch driving and control technology, and in particular to a driving device and control method for a liquid crystal modulation type on-chip integrated optical switch. Background Technology

[0002] In the digital information age, while various digital applications enhance social productivity and provide convenience for life, they inevitably generate massive amounts of data, thus requiring stronger information processing capabilities to meet these demands. Optical switches, as core devices for enabling the switching and path changing of optical signals, have wide applications in information interaction and processing within optical communication networks. In the application of optical switches, their response and switching speeds are crucial performance indicators, and these speeds are influenced by drive control technology. Therefore, drive control technology is of great significance for improving the performance of optical switches.

[0003] Currently, on-chip integrated optical switches mainly include MEMS (Micro-Electro-Mechanical Systems) type, thermo-optical modulation type, and electro-optical modulation type, each with different driving control methods. MEMS-type optical switches primarily utilize electrostatic forces to induce micro-mechanical movement in internal micro-mirrors, thereby achieving path switching. Thermo-optical modulation type optical switches mainly utilize the thermo-optic effect, generating heat by applying electricity to the electrodes, thus changing the refractive index of the waveguide and modulating the light transmitted in the waveguide. Electro-optical modulation type optical switches are driven similarly to thermo-optical modulation type optical switches, changing the refractive index of the optoelectronic material by applying electricity to its ends, thereby achieving modulation. Because the working principles of each type of optical switch are different, none of the above driving control technologies can be applied to liquid crystal modulation type optical switches.

[0004] Liquid crystal modulation on-chip integrated optical switches are a novel type of optical switch, possessing advantages such as low power consumption, high bandwidth, low cost, and high speed, and have great application potential. In the current state of liquid crystal modulation on-chip integrated optical switches, the liquid crystal molecules are initially aligned perpendicularly to the conductive layer under the influence of the alignment layer. When the optical switch unit needs to perform phase modulation to achieve path switching, a voltage is applied to the electrodes, generating an electric field between the two electrodes. The perpendicularly aligned liquid crystal molecules will then tend to align parallel to the conductive layer along the direction of the electric field, thereby changing the refractive index and modulating the light transmitted in the waveguide. When modulation ends, the liquid crystal molecules return to their perpendicular state under their own elastic force, but this recovery process takes longer than the deflection time of the liquid crystal molecules under electrical drive.

[0005] Patent CN113126372A discloses an optical waveguide interference structure, which is a liquid crystal modulation type on-chip integrated optical switch based on a Mach-Zehnder interferometer. A modulation layer is located above the Mach-Zehnder interferometer to modulate it. The modulation layer includes a conductive layer 1 (electrode 1 and electrode 2), a conductive layer 2, and an intermediate liquid crystal layer, which is in contact with the modulation arm waveguide of the Mach-Zehnder interferometer. During operation, the conductive layer drives the liquid crystal molecules in contact with the waveguide, causing them to deflect and modulate the light transmitted in the modulation arm waveguide, thereby achieving a switching effect. Therefore, the driving control technology of the liquid crystal optical switch has a significant impact on its performance.

[0006] There is an urgent need for a driving control technology that matches the on-chip integrated optical switch structure of liquid crystal modulation to give full play to its performance advantages. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a driving device and control method for a liquid crystal modulation type on-chip integrated optical switch.

[0008] The technical solution adopted by the present invention to solve the above problems is: a driving device for a liquid crystal modulation type on-chip integrated optical switch, comprising...

[0009] An optical switch network is composed of an array of optical switch units. Each optical switch unit includes a first conductive layer, a liquid crystal layer and a second conductive layer arranged in sequence. A first electrode and a second electrode are disposed in the first conductive layer.

[0010] A first logic switch is used to control the potential of the first electrode in the optical switch unit;

[0011] The second logic switch is used to control the potential of the second conductive layer in the optical switch unit;

[0012] A digital-to-analog converter unit is used to convert digital signals into analog voltages for corresponding output channels, thereby controlling the electrode potentials of the optical switch unit. The digital-to-analog converter unit includes a DAC chip and peripheral circuitry to ensure its normal operation.

[0013] The microprocessor receives external control signals, processes them, and sends the processing results to the digital-to-analog converter, the first logic switch, and the second logic switch.

[0014] The liquid crystal layer is controlled to switch between a working state and a reset state by controlling the first electrode, the second electrode, and the second conductive layer. In the working state, the orientation of liquid crystal molecules in the liquid crystal layer is changed by adjusting the potential difference between the first electrode and the second electrode. In the reset state, the liquid crystal molecules in the liquid crystal layer are rapidly reset by adjusting the potential difference between the first electrode, the second electrode, and the second conductive layer.

[0015] More specifically, the first logic switch and the second logic switch have the same structure, both including a logic chip, a VDD terminal and a VSS terminal for supplying power to the logic chip, an enable terminal and a gating terminal for receiving signals from the microprocessor, a first input terminal, a second input terminal, and an output terminal. The logic chip can control the connection between the first input terminal and the output terminal or the connection between the second input terminal and the output terminal through the input signal of the gating terminal.

[0016] More specifically, the DAC chip includes several analog voltage output ports. The digital signal input to the DAC chip is converted into analog voltage and then output through the analog voltage output ports.

[0017] More specifically, one of the output ports of the plurality of analog voltages is connected to the second input terminal of the first logic switch, and the remaining output ports of the analog voltages are respectively connected to the second electrodes of different optical switch units.

[0018] More specifically, the DAC chip and the microprocessor transmit signals via a communication connection, which is either SPI or I / O. 2 C;

[0019] More specifically, the microprocessor is connected to the enable and select terminals of the first logic switch and the second logic switch via I / O interfaces; the first input terminal of the first logic switch is grounded, and the second input terminal of the first logic switch is connected to one of the analog voltage output ports on the DAC chip; the first input terminal of the second logic switch is grounded through a pull-down resistor, and the second input terminal of the second logic switch is grounded.

[0020] More specifically, it also includes a path generation unit, which provides external control signals to the microprocessor through button operation.

[0021] More specifically, the path generation unit includes several buttons and a button scanning program. The buttons are arranged in an array. The microprocessor runs the button scanning program to obtain the button status and form a corresponding path number. The optical switch network includes several input ports and several output ports. Each input port corresponds to one button, and each output port corresponds to one button.

[0022] More specifically, the first logic switch, the second logic switch, and the digital-to-analog conversion unit form a group, and at least one group is formed.

[0023] More specifically, there is at least one digital-to-analog conversion unit.

[0024] A control method for the aforementioned drive device, comprising the following steps:

[0025] S1. The microprocessor acquires and processes external operating status control signals.

[0026] S2. The microprocessor processes the received working status control signal into a working digital signal. The working digital signal includes the register address of the output port corresponding to the second electrode of the optical switch unit that needs to be driven and modulated, and the digital value converted into an analog voltage. The microprocessor transmits the working digital signal to the DAC chip and transmits it to the corresponding register according to the register address. The digital values ​​stored in each register are the same or different.

[0027] S3. The microprocessor sends a synchronous output instruction to the DAC chip; at the same time, the microprocessor sends an enable signal and a gating signal to the first logic switch, wherein the enable signal is input to the enable terminal and the gating signal is input to the gating terminal.

[0028] S4. The DAC chip converts the digital value stored in the register into a corresponding analog voltage to provide a high potential to the second electrode in the corresponding optical switch unit. The first logic switch makes the first electrode in all optical switch units at a low potential, and the second logic switch is not working, so that the second conductive layer in all optical switch units is in a non-polarized state. An electric field parallel to the direction of the second conductive layer is formed by the first electrode and the second electrode and drives the liquid crystal molecules.

[0029] A control method for the aforementioned drive device, comprising the following steps:

[0030] D1. The microprocessor acquires and processes the external reset status control signal;

[0031] D2. The microprocessor processes the received reset status control signal into a reset digital signal. The reset digital signal includes the register addresses of all output ports and the digital values ​​converted into analog voltages. The microprocessor transmits the reset digital signal to the DAC chip and to all registers. Each register stores the same digital value.

[0032] D3. The microprocessor sends a synchronous output instruction to the DAC chip; at the same time, the microprocessor sends an enable signal and a gating signal to the first logic switch and the second logic switch, with the enable signal input to the enable terminal and the gating signal input to the gating terminal.

[0033] D4. The digital values ​​stored in all registers are converted into corresponding analog voltages to provide a high potential to the second electrode in the corresponding optical switch unit. The first logic switch is connected to the output port of one of the analog voltages, so that the first electrode in all optical switch units is at a high potential. The second logic switch makes the second conductive layer in all optical switch units at a low potential. An electric field perpendicular to the direction of the second conductive layer is formed through the first electrode, the second electrode and the second conductive layer, and the liquid crystal molecules are reset.

[0034] The beneficial effects of this invention are as follows: By using the aforementioned driving device and control method, the two states of liquid crystal molecules are combined for real-time control and rapid switching. Furthermore, when switching paths after modulation ends, the restoration of the initial vertical orientation of the liquid crystal molecules is accelerated, resulting in faster path switching. This solves the problem that the liquid crystal molecules rely solely on elastic force to slowly restore their original vertical orientation when operating an integrated optical switch on a liquid crystal modulation chip. This significantly improves the switching speed and performance of the optical switch. Existing microcontroller modules, digital-to-analog converter chips, and logic switches have response speeds on the order of microseconds, while the electrical drive response speed of liquid crystal molecules is on the order of milliseconds. Therefore, the speed of the driving device is much faster than the response speed of the liquid crystal molecules. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the optical switch unit of the present invention;

[0036] Figure 2 This is a structural block diagram of the driving device of the present invention;

[0037] Figure 3 This is a schematic diagram of the button connection for the path generation unit;

[0038] Figure 4 This is a schematic diagram of the port information of the first logic switch and the second logic switch of the present invention;

[0039] Figure 5 This is a flowchart of the control method under the working state of the present invention;

[0040] Figure 6 This is a flowchart of the control method in the reset state of the present invention.

[0041] In the diagram: 1. First conductive layer; 2. Liquid crystal layer; 3. Second conductive layer; 4. Button; 11. First electrode; 12. Second electrode; 13. Modulation arm waveguide; SEL, Gating terminal; EN, Enable terminal; S1, First input terminal; S2, Second input terminal; D, Output terminal; R1, Pull-down resistor. Detailed Implementation

[0042] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Furthermore, the technical features involved in the different embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0045] This invention relates to a driving device based on a liquid crystal modulation type on-chip integrated optical switch design, such as... Figure 1The optical switch unit shown includes a first conductive layer 1, a liquid crystal layer 2, and a second conductive layer 3 arranged sequentially. A first electrode 11 and a second electrode 12 are disposed within the first conductive layer 1, and a modulation arm waveguide 13 is disposed within the first conductive layer 1. The first electrode 11 and the second electrode 12 are respectively located on both sides of the modulation arm waveguide 13. Liquid crystal molecules are present within the liquid crystal layer 2, and the liquid crystal molecules are arranged perpendicular to the first conductive layer 1 and the second conductive layer 3. The liquid crystal layer 2 and the two conductive layers together constitute a modulation layer. The liquid crystal molecules have electro-driven characteristics. For positive nematic liquid crystals, under the action of an electric field, the long axis of their molecules will align with the direction of the electric field. Initially, the liquid crystal molecules align perpendicularly to the conductive layer under the action of the alignment layer. When the optical switch unit needs to perform phase modulation to achieve path switching, a voltage is applied to the first electrode 11 and the second electrode 12, generating an electric field between the two electrodes. The vertically aligned liquid crystal molecules will then tend to align parallel to the conductive layer along the direction of the electric field, thereby changing the refractive index above the modulation arm waveguide 13 between the first electrode 11 and the second electrode 12, and thus modulating the light transmitted in the modulation arm waveguide 13. When the modulation ends, the liquid crystal molecules return to their vertical state under their own elastic force, but the time taken for this recovery process is longer than the deflection time of the liquid crystal molecules under electric drive. According to the structural characteristics of this optical switch unit, if a voltage of the same polarity is applied to the two electrodes of the first conductive layer 1, and a voltage of opposite polarity is applied to the second conductive layer 3, an electric field will be formed between the two conductive layers. The liquid crystal molecules will quickly return to their initial vertical state under the combined action of the electric field force and their own elastic force. Therefore, the working state of the optical switch unit can be divided into a horizontally energized state during modulation and a vertically energized state during recovery.

[0046] like Figure 2 The diagram shows a driving device for a liquid crystal modulation type on-chip integrated optical switch, comprising:

[0047] An optical switch network consists of an array of several optical switch units.

[0048] The first logic switch is used to control the potential of the first electrode 11 in the optical switch unit, and can switch the first electrode 11 between a high potential and a low potential.

[0049] The second logic switch is used to control the potential of the second conductive layer 3 in the optical switch unit, and can switch the second conductive layer 3 between no potential and low potential.

[0050] A digital-to-analog converter (DAC) unit is used to convert digital signals into analog voltage signals for the corresponding output channels, thereby controlling the electrode potential of the optical switch unit. The DAC unit includes a DAC chip and peripheral circuitry to ensure its normal operation.

[0051] The microprocessor receives external control signals, processes them, and sends the processing results to the digital-to-analog converter, the first logic switch, and the second logic switch.

[0052] The liquid crystal layer is rapidly switched between working and reset states by controlling the potential levels of the first electrode 11, the second electrode 12, and the second conductive layer 3; the orientation of liquid crystal molecules in the liquid crystal layer is changed by adjusting the potential difference between the first electrode 11 and the second electrode 12; and the liquid crystal molecules in the liquid crystal layer are rapidly reset by adjusting the potential difference between the first electrode 11, the second electrode 12, and the second conductive layer 3.

[0053] Among them, such as Figure 4 The first and second logic switches shown are single-pole double-throw (SPDT) switches of the same structure and model. Each SPDT includes a logic chip, a VDD and VSS terminal for powering the logic chip, an enable terminal EN and a strobe terminal SEL for receiving signals from the microprocessor, a first input terminal S1, a second input terminal S2, and an output terminal D. The VDD terminal is connected to the positive terminal of an external power supply, and the VSS terminal is connected to the negative terminal of the external power supply, thus powering the logic chip. The enable terminal EN and the strobe terminal SEL are connected to the microprocessor's I / O interface. The microprocessor sends an enable signal to the enable terminal EN and a strobe signal to the strobe terminal SEL through the I / O interface, controlling the connection path of the SPDT switch according to the strobe signal. In this scheme, the SPDT switch has three operating states depending on its connection path: connecting the first input terminal S1 and the output terminal D, connecting the second input terminal S2 and the output terminal D, and neither is connected (no enable signal, open circuit).

[0054] In the first logic switch, the output terminal D is connected to the first electrode 11 in all optical switch units within the optical switch network, the first input terminal S1 is grounded, and the second input terminal S2 is connected to one of the analog voltage output ports of the DAC chip.

[0055] In the second logic switch, the output terminal D is connected to the second conductive layer 3 in the optical switch unit, the first input terminal S1 is grounded through a pull-down resistor R1, and the second input terminal S2 is grounded.

[0056] The digital-to-analog converter (DAC) unit is powered by an external power supply and is connected to the DAC chip via peripheral circuits such as voltage regulator capacitors. It can communicate with a microprocessor, which controls the DAC chip to convert the received digital signal into an analog voltage. The DAC chip has multiple output ports for analog voltage output. One output port is connected to the second input terminal S2 of the first logic switch, and each of the remaining output ports corresponds to and is connected to a second electrode 12 within an optical switch unit. Each output port can independently control the potential of the second electrode 12 within its corresponding optical switch unit. Each output port has a built-in register that stores the digital value converted to analog voltage from the microprocessor's output. It waits for the microprocessor to send a synchronization output signal, at which point the DAC chip controls the register to convert the digital value back to analog voltage and output it synchronously. The communication method between the DAC chip and the microprocessor includes SPI or I / O. 2 C, etc.

[0057] The microprocessor is a minimal system with control functions, such as a microcontroller (MCU) or FPGA. The microprocessor processes the received external control signals and converts them into digital signals for output. The microprocessor is connected to the enable terminals EN of the first logic switch and the second logic switch through different I / O interfaces. The microprocessor can be connected to the select terminals SEL of the first logic switch and the second logic switch simultaneously through one I / O interface, or it can be connected to the select terminals SEL of the first logic switch and the second logic switch through different I / O interfaces.

[0058] Based on the above structure, a path generation unit is designed to transmit signals with the microprocessor. This path generation unit can be manually controlled.

[0059] like Figure 3The path generation unit shown includes several buttons 4 and a button scanning program. If the number of input ports and output ports of the optical switch network is N, then the number of buttons 4 is 2N, arranged in an N*2 array in two columns. The input ports of the optical switch network correspond one-to-one with the buttons 4 in the first column, and the output ports of the optical switch network correspond one-to-one with the buttons 4 in the second column. For example, the third button 4 in the first column corresponds to the third input port of the optical switch network, and the fourth button 4 in the second column corresponds to the fourth output port of the optical switch network. Each row and each column of buttons 4 is connected to a microprocessor, which can achieve connection and signal transmission through I / O interfaces. By controlling the buttons 4, the path of the corresponding optical switch network can be activated by controlling the two buttons 4 corresponding to the input port and the output port respectively. For example, pressing the third button 4 in the first column and the fourth button 4 in the second column means that the path from the third input port to the fourth output port is activated. After a button 4 is pressed, the button scanning program runs and generates path information according to the pressed state of the button 4. The path generation unit can generate up to N*N control signals through 2N buttons 4, realizing the control of an N*N scale optical switch network. There is no need for the host computer to send control commands, which has great flexibility. At the same time, it can intuitively reflect the switching of the corresponding path, which has great simplicity. If the operation of button 4 does not meet the condition that only one button 4 is pressed in the first column and the second column respectively, the button scanning program will continue to scan until the correct path information is identified.

[0060] Furthermore, the first logic switch, the second logic switch, and the digital-to-analog converter can be grouped together, with at least one group. Each group can correspond to an equal or unequal number of optical switch units, and the groups can be expanded and increased according to the actual number of optical switch units used. The first logic switch, the second logic switch, and the digital-to-analog converter can be composed of a standard module, which can be added or removed and cascaded as needed during use. Alternatively, only the digital-to-analog converter can be designed as at least one expandable module. The first logic switch and the second logic switch control all optical switch units. A single expandable digital-to-analog converter can control some optical switch units, and multiple expandable digital-to-analog converters combined can control all optical switch units.

[0061] Based on the aforementioned drive device, a control method is formed to control two states of the drive device, namely the working state and the reset state.

[0062] When the drive unit is in operation, such as Figure 5 The steps of the control method shown are as follows:

[0063] S1. The microprocessor unit acquires and processes external working status control signals. The working status control signals can be issued by the host computer or provided by the path generation unit with button 4 mentioned above.

[0064] S2. The microprocessor processes the received operating status control signal into an operating digital signal, wherein the operating digital signal includes the register address of the output port corresponding to the second electrode of the optical switch unit to be driven and modulated, and the digital value converted into an analog voltage; the microprocessor transmits the operating digital signal to the DAC chip, and the DAC chip transmits the digital value of the corresponding voltage to the register for storage according to the register address. The digital value stored in each register can be the same or different, which needs to be set according to the actual working requirements of each optical switch unit;

[0065] S3. After all working digital signals have been transmitted, the microprocessor sends a synchronous output command to the DAC chip. At the same time, the microprocessor sends an enable signal and a gating signal to the first logic switch through the I / O interface. The enable signal enters the enable terminal EN of the first logic switch and starts the first logic switch. The gating signal enters the gating terminal SEL of the first logic switch.

[0066] S4, the DAC chip converts the digital value stored in the register into the corresponding analog voltage and outputs it through the output port to provide a high potential to the second electrode 12 in the corresponding optical switch unit; the first logic switch selects a suitable path according to the gating signal so that the first electrode 11 in the selected optical switch unit is at a low potential, the second logic switch does not work, and the second conductive layer 3 in the photoelectric switch unit is in a non-polar state; there is a potential difference between the first electrode 11 and the second electrode 12, forming an electric field parallel to the direction of the second conductive layer 3, causing the liquid crystal molecules to rotate in the direction parallel to the second conductive layer 3.

[0067] When the drive device is in the reset state, such as Figure 6 The steps of the control method shown are as follows:

[0068] D1. The microprocessor acquires and processes the external reset status control signal, which can be provided by the host computer or an external interrupt signal.

[0069] D2. The microprocessor processes the received reset status control signal into a reset digital signal. The reset digital signal includes the addresses of all output port registers and the digital values ​​converted into analog voltages. The microprocessor transmits the reset digital signal to the DAC chip and to all registers. The digital values ​​stored in each register are the same.

[0070] D3. The microprocessor sends a synchronous output instruction to the DAC chip; at the same time, the microprocessor sends an enable signal and a gating signal to the first logic switch and the second logic switch. The enable signal enters the enable terminal EN of the first logic switch and the second logic switch and starts the first logic switch and the second logic switch. The gating signal enters the gating terminal SEL of the first logic switch and the second logic switch.

[0071] D4. All digital values ​​stored in the registers are converted into corresponding analog voltages and output through the output ports to provide a high potential to the second electrode 12 in the corresponding optical switch unit. The first logic switch selects a suitable path according to the gating signal to ensure connection with one of the output ports, so that the first electrode 11 in all optical switch units is at a high potential. The second logic switch selects a suitable path according to the gating signal, so that the second conductive layer 3 in all optical switch units is at a low potential. An electric field perpendicular to the direction of the second conductive layer 3 is formed by the voltage difference between the first electrode 11 and the second conductive layer 3, and between the second electrode 12 and the second conductive layer 3. This electric field causes the liquid crystal molecules to rotate in the direction perpendicular to the second conductive layer 3 for reset.

[0072] Based on the specific structure of the drive device and the control methods for the two states, the following operation flow can be formed:

[0073] First, the MCU starts the key scanning program to scan the keys. When a key representing an input port and a key representing an output port are pressed (i.e., only one key in the first column and one key in the second column are pressed), it indicates that the path is selected (for example, if the second key in the first column and the third key in the second column are pressed, it indicates that the path from the second input port to the third output port of the network array composed of optical switch units is selected). Under the detection of the key scanning program, the path information is identified and the corresponding path number is generated.

[0074] Subsequently, the MCU will jump to the digital signal generation module inside the MCU according to the path number to execute the program, and generate the corresponding working digital signal according to the path number; the working digital signal includes the register address of the output port corresponding to the second electrode of the optical switch unit that needs to be driven to implement the path, and the digital value converted to analog voltage; the working digital signal is transmitted through SPI or I 2 The communication method of C transmits the data to the DAC chip, and according to different register addresses, the digital value of the corresponding analog voltage is transmitted to the register of different output ports for storage, until all working digital signals of this path have been transmitted.

[0075] Subsequently, the MCU sends a synchronous output command to the DAC chip. The digital values ​​in the registers of all output ports that receive digital values ​​are converted into corresponding analog voltages and output to the second electrode 12 of the corresponding optical switch unit. At the same time, the MCU sends an enable signal and a strobe signal through the I / O interface to activate the first logic switch. The first input terminal S1 of the first logic switch is connected to the output terminal D. At this time, the second conductive layer 3 of all optical switch units is non-polarized, the first electrode 11 of all optical switch units is grounded, and the second electrode 12 of the optical switch unit connected to the output port of the output analog voltage is the set analog voltage. An electric field parallel to the direction of the second conductive layer 3 is formed between the first electrode 11 and the second electrode 12 in a specific optical switch unit, driving the liquid crystal molecules horizontally parallel to the second conductive layer 3, thereby modulating the transmitted light in the modulation arm waveguide 13 and realizing path switching.

[0076] After modulation ends, a reset operation can be performed. The modulation end signal (i.e., the reset control signal, generated by an external interrupt) is received by the MCU. The digital signal generation module inside the MCU inputs the digital value of the corresponding analog voltage to the registers of all analog voltage output ports until all digital values ​​have been transmitted.

[0077] Finally, the MCU sends a synchronous output command to the DAC chip. The digital value in the DAC chip's control register is converted into the corresponding analog voltage and simultaneously output to the second electrode 12 in all optical switch units. Simultaneously, the MCU sends an enable signal to the second logic switch via the I / O interface, and then sends a strobe signal to the first and second logic switches. The first and second logic switches, through the strobe signal, connect the second input terminal S2 to the output terminal D. At this time, the first electrode 11 and the second electrode 12 in all optical switch units are connected to the analog voltage output port, thus ensuring that the first electrode 11 and the second electrode 12 have the same potential. The second conductive layer 3 is a ground terminal. An electric field perpendicular to the direction of the second conductive layer 3 is formed between the first electrode 11 and the second conductive layer 3, and between the second electrode 12 and the second conductive layer 3. This electric field acts on the liquid crystal molecules, accelerating their return to their initial state perpendicular to the second conductive layer 3, thereby improving the reset response speed of the optical switch unit.

[0078] For path switching, the above control method can also be changed to first perform a reset operation on the liquid crystal molecules, and then perform a working operation to realize path switching. This way, each path switching starts from the initial state, eliminating the influence of the previous path, and can directly switch from one path to the next without using an external interrupt to restore the initial state before switching paths.

[0079] Experiments were conducted using the aforementioned driving device and driving method. For a 2µm thick liquid crystal layer, different driving voltages were applied to it in the parallel direction, and the time it took to recover to the vertical state using only elastic force was measured. In the vertical direction, different driving voltages were applied to it, and the time it took to recover to the vertical state was measured. The results are shown in the table below. The recovery time when the vertical direction was energized was shorter than the time when it recovered using only elastic force, and the advantage became more obvious as the voltage increased, proving that the present invention can improve the switching speed of the optical switch unit.

[0080]

[0081]

[0082] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A driving device for a liquid crystal modulation type on-chip integrated optical switch, characterized in that, include The optical switch network is composed of an array of optical switch units. Each optical switch unit includes a first conductive layer (1), a liquid crystal layer (2) and a second conductive layer (3) arranged in sequence. A first electrode (11) and a second electrode (12) are arranged in the first conductive layer (1). A first logic switch is used to control the potential of the first electrode (11) in the optical switch unit; The second logic switch is used to control the potential of the second conductive layer (3) in the optical switch unit; A digital-to-analog converter unit is used to convert digital signals into analog voltages for corresponding output channels, thereby controlling the electrode potentials of the optical switch unit. The digital-to-analog converter unit includes a DAC chip and peripheral circuitry to ensure its normal operation. The microprocessor receives external control signals, processes them, and sends the processing results to the digital-to-analog converter, the first logic switch, and the second logic switch. The first logic switch and the second logic switch have the same structure, both including a logic chip, a VDD terminal and a VSS terminal for supplying power to the logic chip, an enable terminal and a gating terminal for receiving signals from the microprocessor, a first input terminal, a second input terminal, and an output terminal. The logic chip can control the connection between the first input terminal and the output terminal or between the second input terminal and the output terminal through the input signal of the gating terminal. The DAC chip includes several analog voltage output ports. Digital signals input to the DAC chip are converted into analog voltages and then output through the analog voltage output ports. One of the output ports of the plurality of analog voltages is connected to the second input terminal of the first logic switch, and the remaining output ports of the analog voltages are respectively connected to the second electrodes (12) of different optical switch units; The microprocessor is connected to the enable and select terminals of a first logic switch and a second logic switch via I / O interfaces; the first input terminal of the first logic switch is grounded, and the second input terminal of the first logic switch is connected to one of the analog voltage output ports on the DAC chip; the first input terminal of the second logic switch is grounded through a pull-down resistor, and the second input terminal of the second logic switch is also grounded. The liquid crystal layer is controlled to switch between working state and reset state by controlling the first electrode (11), the second electrode (12) and the second conductive layer (3); in the working state, the orientation of liquid crystal molecules in the liquid crystal layer is changed by adjusting the potential difference between the first electrode (11) and the second electrode (12); in the reset state, the liquid crystal molecules in the liquid crystal layer are rapidly reset by adjusting the potential difference between the first electrode (11), the second electrode (12) and the second conductive layer (3).

2. The driving device for the liquid crystal modulation type on-chip integrated optical switch according to claim 1, characterized in that, The DAC chip and the microprocessor are connected in a communication connection mode for signal transmission, and the communication connection mode is SPI or I 2 C.

3. The driving device for the liquid crystal modulation type on-chip integrated optical switch according to claim 1, characterized in that, It also includes a path generation unit, which provides external control signals to the microprocessor via button operation.

4. The driving device for the liquid crystal modulation type on-chip integrated optical switch according to claim 3, characterized in that, The path generation unit includes several buttons and a button scanning program. The buttons are arranged in an array. The microprocessor runs the button scanning program to obtain the button status and form a corresponding path number. The optical switch network includes several input ports and several output ports. Each input port corresponds to one button, and each output port corresponds to one button.

5. The driving device for a liquid crystal modulation type on-chip integrated optical switch according to claim 1, characterized in that, The first logic switch, the second logic switch, and the digital-to-analog converter form a group, and there is at least one group.

6. The driving device for the liquid crystal modulation type on-chip integrated optical switch according to claim 1, characterized in that, At least one digital-to-analog conversion unit is mentioned.

7. A control method based on the drive device according to any one of claims 1-6, characterized in that, The control method comprises the following steps: S1. The microprocessor acquires and processes external operating status control signals. S2. The microprocessor processes the received working status control signal into a working digital signal. The working digital signal includes the register address of the output port corresponding to the second electrode of the optical switch unit that needs to be driven and modulated, and the digital value converted into an analog voltage. The microprocessor transmits the working digital signal to the DAC chip and transmits it to the corresponding register according to the register address. The digital values ​​stored in each register are the same or different. S3. The microprocessor sends a synchronous output instruction to the DAC chip; at the same time, the microprocessor sends an enable signal and a gating signal to the first logic switch, wherein the enable signal is input to the enable terminal and the gating signal is input to the gating terminal. S4. The DAC chip converts the digital value stored in the register into the corresponding analog voltage and provides a high potential to the second electrode (12) in the corresponding optical switch unit. The first logic switch makes the first electrode (11) in all optical switch units at a low potential. The second logic switch is not working, so that the second conductive layer (3) in all optical switch units is in a non-polar state. An electric field parallel to the direction of the second conductive layer (3) is formed by the first electrode (11) and the second electrode (12) and drives the liquid crystal molecules.

8. A control method based on the drive device according to any one of claims 1-6, characterized in that, The control method comprises the following steps: D1. The microprocessor acquires and processes the external reset status control signal; D2. The microprocessor processes the received reset status control signal into a reset digital signal. The reset digital signal includes the register addresses of all output ports and the digital values ​​converted into analog voltages. The microprocessor transmits the reset digital signal to the DAC chip and to all registers. Each register stores the same digital value. D3. The microprocessor sends a synchronous output instruction to the DAC chip; at the same time, the microprocessor sends an enable signal and a gating signal to the first logic switch and the second logic switch, with the enable signal input to the enable terminal and the gating signal input to the gating terminal. D4. All the digital values ​​stored in the registers are converted into corresponding analog voltages to provide a high potential to the second electrode (12) in the corresponding optical switch unit. The first logic switch is connected to the output port of one of the analog voltages so that the first electrode (11) in all optical switch units is at a high potential. The second logic switch makes the second conductive layer (3) in all optical switch units at a low potential. An electric field perpendicular to the direction of the second conductive layer (3) is formed through the first electrode (11), the second electrode (12) and the second conductive layer (3) and resets the liquid crystal molecules.

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