High-speed high-extinction-ratio cascade MZI electro-optical switch based on electro-optical material

Abstract

The invention discloses a high-speed and high-extinction-ratio cascade MZI (Mach Zehnder Interferometer) electro-optical switch based on an electro-optical material. According to the electro-optical switch, a plurality of MZI structures are cascaded and integrated on an electro-optical material platform (such as lithium niobate or lithium tantalate) with an ultra-wide optical transparent window, and the initial phase error of each modulation arm is subjected to thermo-optical calibration by utilizing the refractive index change of an electro-optical material caused by temperature regulation and control; therefore, the consistency and long-term stability of the initial phase of the cascaded MZI are ensured. After thermo-optical phase calibration is completed, electro-optical refractive index regulation and control can be carried out on a plurality of phase modulation arms of the cascaded MZI at the same time only by applying a single driving voltage, and optical switch switching with the ultrahigh extinction ratio is achieved. The device has a pre-calibration function, a working point is stable and does not drift after calibration, and high-speed and high-extinction-ratio switching can be achieved only through a high-speed signal; and meanwhile, the device has the advantages of simple structure, flexible design, easiness in cascade expansion, low requirement on technological parameter tolerance and the like.

Description

Technical Field

[0001] This invention relates to an optical switching device, and more particularly to a high-speed, high-extinction-ratio cascaded MZI (Mach-Zehnder interferometer) electro-optic switch based on electro-optic materials. Background Technology

[0002] The rapid development of quantum information processors has made the emergence of quantum computers possible, but commercial quantum computers require the parallel control of millions of single quantum gates. Currently, the mainstream neutral atom physics platform suitable for quantum information processors can achieve large-capacity qubits, high-density connections, and massively parallel processing, demonstrating enormous potential in the field of large-scale quantum computing. The control of such systems essentially relies on optical technology: from cooling and trapping to executing high-fidelity quantum gates, multiple stages of its operation require precisely shaped and modulated laser pulse arrays. However, current discrete optoelectronic devices have significant limitations in terms of scale.

[0003] Integrated optical platforms can achieve parallel operation of large-scale integrated optical switching units on centimeter-scale chips, but the requirements for quantum control are particularly stringent, which is closely related to the needs of fault-tolerant quantum computing. First, a feasible platform must operate efficiently within specific wavelength bands (780nm, 850nm) to drive the specific transitions required for qubit control. Switching speeds must be on the order of microseconds to achieve gate operations much faster than the decoherence time of the qubits. Most critically, the on / off extinction ratio (ER) of the optical modulator must be extremely high. Photons leaking from the closed channel can drive idle qubits to produce unwanted rotations, causing gate operation errors to worsen with increasing leakage field strength or light intensity. To reduce gate fidelity below the quantum error correction threshold (typically below 10⁻⁶), further stringent requirements must be met. -3 Therefore, the photon error of a single quantum gate must be suppressed to 10. -4 This requires achieving an extinction ratio exceeding 40 dB, a benchmark that is extremely challenging for integrated devices. Currently, mainstream silicon-on-insulator (SOI) platforms can only achieve switching state transitions through thermal tuning. The millisecond-level switching rate severely affects the number of operations a single quantum gate can perform within the decoherence time, and also suffers from problems such as excessive absorption in the visible light band and excessive overall insertion loss.

[0004] To overcome existing technological limitations, there is an urgent need to develop a new type of on-chip optical switch device, which will provide core technological support for realizing a truly high-speed, high-extinction-ratio, focused neutral atom platform-controlled large-scale integrated optical switch array. Summary of the Invention

[0005] To address the problems existing in the background technology, this invention discloses a high-speed, high-extinction-ratio cascaded MZI (Mach-Zehnder interferometer) electro-optic switch based on electro-optic materials. This electro-optic switch integrates multiple MZI structures cascaded onto an electro-optic material platform (such as lithium niobate or lithium tantalate) with an ultra-wide optically transparent window. It utilizes the temperature-controlled refractive index change of the electro-optic material to perform thermo-optic calibration of the initial phase error of each modulation arm, thereby ensuring the consistency and long-term stability of the initial phase of the cascaded MZI. After completing the thermo-optic phase calibration, this invention only requires the application of a single driving voltage to simultaneously perform electro-optic refractive index control on multiple phase modulation arms of the cascaded MZI, achieving high-speed (<1μs) and high extinction-ratio (>40dB) optical switch switching. This invention features a pre-calibration function; the operating point is stable and drift-free after calibration, requiring only a single high-speed signal to achieve high-speed, high-extinction-ratio switching. It also boasts advantages such as simple structure, flexible design, easy cascading expansion, and low tolerance requirements for process parameters.

[0006] The technical solution adopted in this invention is as follows: I. A high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials The optical switch comprises multiple cascaded MZIs. One output port of the preceding MZI is connected to one input port of the following MZI via a connecting waveguide. A first single-mode end-face coupler is connected to one of the input ports of the first MZI and is used to input optical signals. A second single-mode end-face coupler is connected to one of the output ports of the last MZI and is used to output optical signals. Each MZI has a corresponding optical signal absorption component at one input port and one output port, both of which are in an unused state. Each MZI includes a switch phase error calibration component and a switch state control component.

[0007] The MZI includes two multimode interference couplers. One port of the two multimode interference couplers is connected through a modulation arm waveguide, and the other port of the two multimode interference couplers is connected through another modulation arm waveguide. A corresponding switch state control component is placed at one end of each modulation arm waveguide, and a corresponding switch phase error calibration component is placed at the other end of each modulation arm waveguide.

[0008] The switching state control component includes a push-pull electrode modulator. Multiple electrode branches of the first metal traveling-wave electrode of the push-pull electrode modulator are respectively placed outside the modulation arm waveguide of each MZI, and multiple electrode branches of the second metal traveling-wave electrode are respectively placed inside the two modulation arm waveguides of each MZI. The number of electrode branches of the first metal traveling-wave electrode minus one equals the number of electrode branches of the second metal traveling-wave electrode, and multiple MZIs require only one high-speed drive signal.

[0009] The switching phase error calibration component includes a metal thermoelectric electrode. The metal thermoelectric electrode is placed on the modulation arm waveguide.

[0010] The connecting waveguide includes a bent waveguide.

[0011] The multimode interference coupler is a 2×2 multimode interference coupler with a 50:50 splitting ratio.

[0012] II. A method for switching the state of an optical signal A reference optical signal is introduced into the high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials. The phase error calibration component corresponding to each MZI in the optical switch is adjusted so that the initial phase of the optical switch is consistent with the theory, that is, it reaches the "0" state, thus completing the phase error calibration. The target optical signal is then introduced into the phase error calibrated optical switch to control the switch state control component in the optical switch, that is, to introduce a square wave signal, thereby realizing the state switching of the target optical signal.

[0013] III. An optical switch array The optical switch array comprises several of the aforementioned high-speed, high-extinction-ratio cascaded MZI electro-optic switches based on electro-optic materials. The beneficial effects of this invention are: This invention is a high-speed, high-extinction-ratio cascaded MZI electro-optic switch suitable for large-scale on-chip optical switch arrays. It has the advantages of simple process and simple structure, and has excellent performance such as real-time fast static phase calibration, low inter-channel crosstalk, low insertion loss, ultra-high extinction ratio, and ultra-fast modulation.

[0014] This invention, by introducing thermoelectric electrodes and metal absorbing electrodes, fully analyzes the influencing factors of extinction ratio, including inter-channel crosstalk, phase error, and waveguide backscattered light, thereby achieving initial phase calibration of cascaded MZI, which can be flexibly changed and easily adjusted.

[0015] This invention utilizes a push-pull electrode modulation method to load electrical signals onto cascaded MZIs, enabling the output optical switch signal to switch states rapidly, and requiring only one high-speed drive signal for multiple MZIs.

[0016] This invention introduces an electro-optic material system, which simplifies the overall chip design and system structure, while also reducing chip power consumption and circuit losses, and simplifying the phase control method. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the optical switch of the present invention.

[0018] Figure 2 It is the cross-section of the waveguide structure of the optical switch. Figure 1 .

[0019] Figure 3 It is the cross-section of the waveguide structure of the optical switch. Figure 2 .

[0020] Figure 4 It is the cross-section of the waveguide structure of the optical switch. Figure 3 .

[0021] Figure 5 These are the extinction ratio and half-wave voltage of the optical switch.

[0022] Figure 6 It refers to the switching speed (rise edge time) of the optical switch.

[0023] In the figure: First single-mode end-face coupler 1a, second single-mode end-face coupler 1b, first multimode interference coupler 2a, second multimode interference coupler 2b, third multimode interference coupler 2c, fourth multimode interference coupler 2d, first modulation arm waveguide 3a, second modulation arm waveguide 3b, third modulation arm waveguide 3c, fourth modulation arm waveguide 3d, first connecting bend waveguide 4a, first metal thermoelectric electrode 5a, second metal thermoelectric electrode 5b, third metal thermoelectric electrode 5c, fourth metal thermoelectric electrode 5d, first metal push-pull electrode 6a, second metal push-pull electrode 6b, first metal absorbing electrode 7a, second metal absorbing electrode 7b, third metal absorbing electrode 7c, fourth metal absorbing electrode 7d, upper cladding 100, core ridge electro-optic material waveguide 101, lower cladding 102, silicon substrate 103, electrode 104. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] This embodiment uses two MZIs as an example to specifically illustrate the optical switch of the present invention.

[0026] like Figure 1As shown, the optical switch includes a first single-mode end-face coupler 1a, a second single-mode end-face coupler 1b, a first multimode interference coupler 2a, a second multimode interference coupler 2b, a third multimode interference coupler 2c, a fourth multimode interference coupler 2d, a first modulation arm waveguide 3a, a second modulation arm waveguide 3b, a third modulation arm waveguide 3c, a fourth modulation arm waveguide 3d, a first connecting bend waveguide 4a, a first metal thermoelectric electrode 5a, a second metal thermoelectric electrode 5b, a third metal thermoelectric electrode 5c, a fourth metal thermoelectric electrode 5d, a first metal push-pull electrode 6a, a second metal push-pull electrode 6b, a first metal absorption electrode 7a, a second metal absorption electrode 7b, a third metal absorption electrode 7c, and a fourth metal absorption electrode 7d; a single-wavelength optical signal is controlled by the first single-mode... The input terminal of end-face coupler 1a receives the signal, which is then input into the first multimode interference coupler 2a via the first single-mode end-face coupler 1a. The signal is then divided into two parts, which respectively enter the first modulation arm waveguide 3a and the second modulation arm waveguide 3b and are transmitted along the waveguide transmission direction. The signal is then input into the second multimode interference coupler 2b, where it interferes and is divided into two parts. One part is absorbed by the second metal absorbing electrode 7b, and the other part is input into the third multimode interference coupler 2c via the first connecting bend waveguide 4a. The signal is then divided into two parts, which respectively enter the third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d and are transmitted along the waveguide transmission direction. The signal is then input into the fourth multimode interference coupler 2d, where it interferes and is divided into two parts. One part is absorbed by the fourth metal absorbing electrode 7d, and the other part is output after passing through the second single-mode end-face coupler 1b.

[0027] After entering the first multimode interference coupler 2a, the two parts of light are split into two parts and then thermo-optically modulated in the first modulation arm waveguide 3a and the second modulation arm waveguide 3b. Different splitting ratios are achieved through the second multimode interference coupler 2b to realize the state calibration of the first-stage MZI.

[0028] After entering the third multimode interference coupler 2c, the two parts of light are split into two parts and then thermo-optically modulated in the third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d. Different splitting ratios are achieved through the fourth multimode interference coupler 2d to realize the state calibration of the second-stage MZI.

[0029] The light entering the first single-mode end-face coupler 1a is electro-optically modulated by a single drive through the cascaded MZI in the first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d. Different optical power outputs are achieved through the second single-mode end-face coupler 1b, realizing the switching of the switching state.

[0030] The first single-mode end-face coupler 1a and the second single-mode end-face coupler 1b are placed in parallel and have the same shape. Optionally, both the first single-mode end-face coupler 1a and the second single-mode end-face coupler 1b are inverted cone shapes.

[0031] The first multimode interference coupler 2a, the second multimode interference coupler 2b, the third multimode interference coupler 2c, and the fourth multimode interference coupler 2d are all identical in shape and are all 2×2 multimode interference couplers with a 50:50 splitting ratio. The first multimode interference coupler 2a and the second multimode interference coupler 2b are located on the same horizontal straight line, and the third multimode interference coupler 2c and the fourth multimode interference coupler 2d are located on the same horizontal straight line.

[0032] The first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d are placed in parallel. The distance between the first modulation arm waveguide 3a and the second modulation arm waveguide 3b is the same as the distance between the third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d. The first modulation arm waveguide 3a and the second modulation arm waveguide 3b are located on both sides of the first multimode interference coupler 2a and the second multimode interference coupler 2b and are equidistant from each other. The third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d are located on both sides of the third multimode interference coupler 2c and the fourth multimode interference coupler 2d and are equidistant from each other. The waveguide lengths of the first modulation arm waveguide 3a and the second modulation arm waveguide 3b can be the same or different. If the waveguide lengths of the first modulation arm waveguide 3a and the second modulation arm waveguide 3b are different, the phase error caused by the different lengths can be overcome by phase error calibration.

[0033] Each of the first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d is equipped with metal electrodes for calibrating the switching phase error, namely the first metal thermoelectric electrode 5a, the second metal thermoelectric electrode 5b, the third metal thermoelectric electrode 5c, and the fourth metal thermoelectric electrode 5d. The cross-section of the waveguide structure is as follows: Figure 2 As shown, the single-mode end-face coupler, the modulation arm straight waveguide, the multimode interference coupler waveguide, and all waveguides connecting the waveguides are made of electro-optic materials. The first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d are made of ferroelectric materials. By applying different voltages to the metal electrodes, the refractive index of the ferroelectric materials is changed through the thermo-optic effect, thereby calibrating the phase error of the cascaded MZI optical switch.

[0034] Each of the first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d is provided with metal electrodes for controlling the switching state, namely the first metal push-pull electrode 6a and the second metal push-pull electrode 6b. The cross-section of the waveguide structure is as follows: Figure 3As shown, metal electrodes 104 are arranged on the sides of the front half of the core-ridge electro-optic material waveguide 101 in the first modulation arm waveguide 3a, second modulation arm waveguide 3b, third modulation arm waveguide 3c, and fourth modulation arm waveguide 3d. The metal electrodes 104 and the core-ridge electro-optic material waveguide 101 are located in the hollowed-out region of the upper cladding 100. The first modulation arm waveguide 3a, second modulation arm waveguide 3b, third modulation arm waveguide 3c, and fourth modulation arm waveguide 3d are made of ferroelectric materials. A voltage is applied to the metal electrodes through a single driving voltage, and then the domain orientation of the ferroelectric material is controlled through the electro-optic effect to achieve high-speed modulation of the optical refractive index, thereby controlling the operation of the cascaded MZI optical switch.

[0035] Above the rear half of the first modulation arm waveguide 3a, second modulation arm waveguide 3b, third modulation arm waveguide 3c, and fourth modulation arm waveguide 3d, there are first metal thermoelectric electrodes 5a, second metal thermoelectric electrodes 5b, third metal thermoelectric electrodes 5c, and fourth metal thermoelectric electrodes 5d, parallel to the waveguides. One end of each of the first, second, third, and fourth metal thermoelectric electrodes 5a, 5b, 5c, and 5d is grounded, and the other end is connected to a multi-channel current source for controlling metal heating. Specifically, the negative terminals of the first, second, third, and fourth metal thermoelectric electrodes 5a, 5b, 5c, and 5d are connected together via traces and can be grounded simultaneously. The positive terminals are connected to different ports of the multi-channel voltage source via traces, allowing for simultaneous regulation of different voltages. A first metal push-pull electrode 6a and a second metal push-pull electrode 6b are provided next to the front half of the first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d. The lateral portions of the first metal push-pull electrode 6a and the second metal push-pull electrode 6b are parallel to the first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d, and the portion crossing the waveguide is perpendicular to the lateral portion. The first metal push-pull electrode 6a is grounded, and the second metal push-pull electrode 6b is connected to an external signal generator for receiving switching signals.

[0036] Because of the backscattered optical power in the waveguide, and to prevent interference between the backscattered light and the forward-propagating light from generating higher-order modes, the ports adjacent to the signal input terminals of the first multimode interference coupler 2a, the second multimode interference coupler 2b, the third multimode interference coupler 2c, and the fourth multimode interference coupler 2d are equipped with a first metal absorbing electrode 7a, a second metal absorbing electrode 7b, a third metal absorbing electrode 7c, and a fourth metal absorbing electrode 7d, respectively, to eliminate backscattered light. The waveguide structure cross-section is shown below. Figure 4As shown, from top to bottom, the structure comprises an electrode 104, an upper cladding layer 100, a core-layer ridge-shaped electro-optic material waveguide 101, a lower cladding layer 102, and a silicon substrate 103. The first metal absorbing electrode 7a, the second metal absorbing electrode 7b, the third metal absorbing electrode 7c, and the fourth metal absorbing electrode 7d are parallel to the first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d, and do not require connection to external circuitry; they are used to attenuate the optical signal input to this channel.

[0037] The calibration process for the switching phase error is as follows: When the first metal thermoelectrode 5a, the second metal thermoelectrode 5b, the third metal thermoelectrode 5c, and the fourth metal thermoelectrode 5d are not energized, the optical signal is input from the first single-mode end-face coupler 1a. After passing through the first multimode interference coupler 2a, the signal is split into two beams and enters the first modulation arm waveguide 3a and the second modulation arm waveguide 3b, respectively. The two beams re-converge and interfere in the second multimode interference coupler 2b. Most of the light is absorbed by the second metal absorption electrode 7b. The remaining light is split into two beams after passing through the third multimode interference coupler 2c and enters the third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d, respectively. The two beams re-converge and interfere in the fourth multimode interference coupler 2d. Most of the remaining light is absorbed by the fourth metal absorption electrode 7d. The very small portion of the remaining light is output through the second single-mode end-face coupler 1b. At this time, the optical output power is extremely low, corresponding to the "0" state of the optical switch. However, in practice, due to processing errors, surface flatness of the thin film material, etc., the phase of the light signal will change during the transmission of light through the first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, and the fourth modulation arm waveguide 3d. This will cause a certain phase difference between the first modulation arm waveguide 3a and the second modulation arm waveguide 3b, and between the third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d. When interference occurs in the second multimode interference coupler 2b and the fourth multimode interference coupler 2d, it will affect the beam splitting ratio, thereby causing the state of the optical switch to drift and changing the initial "0" state of the optical switch. When the first metal thermoelectrode 5a, the second metal thermoelectrode 5b, the third metal thermoelectrode 5c, and the fourth metal thermoelectrode 5d are energized, the output light power can be detected, and different voltages can be adjusted to compensate for the phase difference generated between the first modulation arm waveguide 3a and the second modulation arm waveguide 3b, and between the third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d through the thermo-optical effect. This ensures that the initial phase of the optical switch is consistent with the theory and reaches the "0" state.

[0038] Voltage is applied via push-pull modulation: the first metal push-pull electrode 6a is grounded, and the second metal push-pull electrode 6b is loaded with a single-drive electrical signal. Through this push-pull modulation, the refractive index changes between the first modulation arm waveguide 3a and the second modulation arm waveguide 3b, and between the third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d, are always equal in magnitude and opposite in direction. Therefore, the resonant optical signal will be output at different ports. Utilizing the electro-optic effect, the light intensity at wavelength λ can be detected at the output port of the second single-mode end-face coupler 1b, meaning the output power has a peak at λ, corresponding to a "1" level. If the applied voltage changes, causing the light with wavelength λ to be absorbed by the ports of the second metal absorbing electrode 7b and the fourth metal absorbing electrode 7d in the second multimode interference coupler 2b and the fourth multimode interference coupler 2d, then the second single-mode end-face coupler 1b, as the output port, will have no light output with wavelength λ, or the intensity will be extremely low, corresponding to a "0" level. If the absolute value of the difference between the voltage V0 that maximizes the light intensity and the voltage V1 that minimizes the light intensity is taken, the half-wave voltage Vpi is obtained. At this time, the extinction ratio of the maximum optical power P0 and the minimum optical power P1 is obtained, which can realize high-speed switching of the switching state.

[0039] Typically, a single driving voltage of varying high and low is applied to the metal electrode at the front end of the straight waveguide of the modulation arm to load a binary switching signal of 0101, thereby achieving the switching of the output signal state of the cascaded optical switch.

[0040] During initialization, a certain current is applied to the metal electrode at the rear section of the straight waveguide of the modulation arm for state calibration, thereby achieving the calibration of the phase error of the monopole MZI modulation arm.

[0041] In one feasible implementation, the first multimode interference coupler 2a, the second multimode interference coupler 2b, the third multimode interference coupler 2c, the fourth multimode interference coupler 2d, the first modulation arm waveguide 3a, the second modulation arm waveguide 3b, the third modulation arm waveguide 3c, the fourth modulation arm waveguide 3d, and the first connecting curved waveguide 4a are all ridge waveguide structures with asymmetrical cross-sections. The optical waveguide core layer is ridge-shaped, and both sides of the ridge are partially etched with the same etching depth.

[0042] Optionally, the upper and lower cladding layers are made of silicon dioxide.

[0043] The waveguide material selection features electro-optic materials with large electro-optic coefficients, high damage thresholds, low refractive index differences, and low DC drift.

[0044] The core layer of all waveguides—single-mode end-face couplers, modulation arm straight waveguides, multimode interference couplers, and connecting waveguides—is made of ferroelectric material. These ferroelectric materials are integrated to form a ferroelectric waveguide. Ferroelectric waveguides exhibit electro-optic and thermo-optic effects, enabling high-speed switching.

[0045] The optical signal state switching method proposed in this invention includes the following steps: A reference optical signal is introduced into a high-speed, high-extinction-ratio cascaded MZI optical switch based on an electro-optic material system. The phase error calibration component corresponding to each MZI in the optical switch is adjusted so that the initial phase of the optical switch is consistent with the theory, that is, it reaches the "0" state, thus completing the phase error calibration. The target optical signal is then introduced into the phase error calibrated optical switch, and the switch state control component in the optical switch is controlled by introducing a single-drive square wave signal to realize the state switching of the target optical signal.

[0046] During phase error calibration, a tunable laser (TL) with a polarizer (PC) and an optical power detector (PD) are connected via end-face coupling. An external multi-channel current source applies a constant current at the thermoelectrode through a probe to calibrate the phase error of the cascaded MZI and bring it to the "0" state.

[0047] In this embodiment of the invention, a signal generator applies a triangular wave signal to the traveling wave electrode portion of the optical switch via a high-speed GSG probe, inputs a single-wavelength optical signal into the optical switch chip, and records the change ΔV of the detected optical power signal using an optical power detector and a subsequent oscilloscope. The extinction ratio (>40dB), half-wave voltage (~3V), and response speed (<1μs) of the optical switch are then calculated. The results for the extinction ratio and half-wave voltage of the optical switch are as follows: Figure 5 As shown, the response speed results are as follows: Figure 6 As shown in the image.

[0048] The following is a specific implementation case of a high-speed, high-extinction-ratio cascaded MZI optical switch.

[0049] In the design of a high-speed, high-extinction-ratio cascaded MZI optical switch, the waveguide widths of the first modulation arm waveguide 3a, second modulation arm waveguide 3b, third modulation arm waveguide 3c, fourth modulation arm waveguide 3d, and first connecting curved waveguide 4a are 1 μm. The curved waveguides are Euler bends with a radius of 60 μm. The multimode interference regions of the first multimode interference coupler 2a, second multimode interference coupler 2b, third multimode interference coupler 2c, and fourth multimode interference coupler 2d have a length of 98.5 μm and a width of 4.5 μm. The port channel spacing is 3 μm, and the port waveguides gradually change from 1.5 μm to 1 μm with a length of 20 μm. The waveguide widths of the first single-mode end-face coupler 1a and second single-mode end-face coupler 1b gradually change from 0.2 μm to 1 μm, and the ribbed waveguide width gradually changes from 0.2 μm to 5 μm. This effectively improves the coupling coefficient and reduces transmission loss while ensuring single-mode transmission.

[0050] The high-speed, high-extinction-ratio cascaded MZI optical switch was fabricated using a lithium-on-insulator (LTOI) material system. The LTOI consists of a 3μm silicon oxide insulating layer and a 250nm thin-film lithium tantalate layer. The refractive index of lithium tantalate is anisotropic. o The value is 2.163, n e The refractive index of silicon oxide is 1.44, and the refractive index of the silicon oxide is 2.168. The fabrication process is as follows: etching of the thin-film lithium tantalate ridge waveguide—secondary etching of the rib region of the single-mode end-face coupler—deposition and wet etching of the silicon oxide cladding film—evaporation of the metal hot electrode—evaporation of the metal push-pull electrode. Specifically, the etching depth of the waveguide is 150 nm; the etching depth of the rib region of the single-mode end-face coupler is 100 nm; the growth height of the silicon oxide cladding is 1.5 μm; the wet etching depth at the metal push-pull electrode is 1.5 μm; the metal hot electrode is a Ti-Au electrode, with a Ti thickness of 120 nm and an Au thickness of 20 nm; the metal push-pull electrode is a Ti-Au electrode, with a Ti thickness of 20 nm and an Au thickness of 500 nm.

[0051] First, end-face coupling is achieved at the first single-mode end-face coupler 1a and the second single-mode end-face coupler 1b via lens fiber. After light transmission, a multi-channel voltage source applies different voltages to the first metal thermoelectrode 5a, the second metal thermoelectrode 5b, the third metal thermoelectrode 5c, and the fourth metal thermoelectrode 5d to minimize the output optical power, thereby calibrating the initial state. This allows the extinction ratios of the MZIs to be superimposed, and the extinction ratio can stably exceed 40dB. Subsequently, a digital signal is output through an arbitrary waveform generator and applied to the first metal push-pull electrode 6a and the second metal push-pull electrode 6b in a push-pull manner to form electro-optic modulation. Since the refractive index changes between the first modulation arm waveguide 3a and the second modulation arm waveguide 3b, and between the third modulation arm waveguide 3c and the fourth modulation arm waveguide 3d, are the same but opposite in direction, the carrier wave will be output at different ports, enabling the optical switch to switch states at speeds up to the nanosecond level. This demonstrates that the cascaded MZI optical switch has the characteristics of high speed and high extinction ratio.

[0052] As can be seen from this implementation, the present invention has a pre-calibration function, and the operating point is stable and drift-free after calibration. Only a high-speed signal is needed to achieve high-speed high extinction ratio switching. At the same time, it also has the advantages of simple structure, flexible design, easy cascading expansion and low tolerance requirements for process parameters.

[0053] 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. A high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials, characterized in that, The system comprises multiple cascaded MZIs, with one output port of the preceding MZI connected to one input port of the following MZI via a connecting waveguide; a first single-mode end-face coupler (1a) is connected to one of the input ports of the first MZI and is used to input optical signals; a second single-mode end-face coupler (1b) is connected to one of the output ports of the last MZI and is used to output optical signals; each MZI has a corresponding optical signal absorption component at one input port and one output port; each MZI also includes a switch phase error calibration component and a switch state control component.

2. The high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials according to claim 1, characterized in that, The MZI includes two multimode interference couplers. One port of the two multimode interference couplers is connected through a modulation arm waveguide, and the other port of the two multimode interference couplers is connected through another modulation arm waveguide. A corresponding switch state control component is placed at one end of each modulation arm waveguide, and a corresponding switch phase error calibration component is placed at the other end of each modulation arm waveguide.

3. The high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials according to claim 1, characterized in that, The switch state control component includes a push-pull electrode modulator.

4. The high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials according to claim 1, characterized in that, The switch phase error calibration component includes a metal thermoelectrode.

5. A high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials according to claim 1, characterized in that, The connecting waveguide includes a bent waveguide.

6. A high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials according to claim 1, characterized in that, The multimode interference coupler is a 2×2 multimode interference coupler with a 50:50 splitting ratio.

7. A high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials according to claim 1, characterized in that, The electro-optical material of the electro-optical switch is lithium niobate or lithium tantalate.

8. A method for switching the state of an optical signal, characterized in that, Includes the following steps: A reference optical signal is introduced into the high-speed, high-extinction-ratio cascaded MZI electro-optic switch based on electro-optic materials as described in claim 1. The phase error calibration component corresponding to each MZI in the optical switch is adjusted so that the initial phase of the optical switch is consistent with the theory, thus completing the phase error calibration. The target optical signal is introduced into the phase error calibrated optical switch, and the switch state control component in the optical switch is controlled to realize the state switching of the target optical signal.

9. An optical switch array, characterized in that, The optical switch array includes several high-speed, high-extinction-ratio cascaded MZI electro-optic switches based on electro-optic materials as described in claim 1.

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