Silicon-based integrated device for synchronously measuring microwave frequency and angle of arrival and measuring method

Abstract

The invention discloses a silicon-based integrated device for synchronously measuring microwave frequency and an angle of arrival and a measuring method. The light source is used for emitting light carriers to the input end of the double-parallel Mach-Zehnder photoelectric intensity modulator, and the two radar antennas arranged at intervals receive microwave signals to be measured and send the microwave signals to the double-parallel Mach-Zehnder photoelectric intensity modulator. The double-parallel Mach-Zehnder photoelectric intensity modulator loads a microwave signal to be measured onto an optical carrier to generate two paths of optical carrier microwave signals and sends the two paths of optical carrier microwave signals to the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit and the arrival angle measurement unit, and rough frequency measurement, fine frequency measurement and arrival angle measurement of the optical carrier microwave signals are carried out respectively. A single structure is adopted, synchronous and efficient measurement of the frequency and the arrival angle of a radar microwave signal is achieved, the detection efficiency is remarkably improved, the technical problem of simultaneous measurement of the microwave frequency and the arrival angle with on-chip integration, high precision, light weight, low power consumption and powerful functions is solved, the practicability of the system is improved, and the application range of the system is widened.

Description

Technical Field

[0001] The present invention belongs to the fields of microwave photonics technology and silicon-based integrated photonics, and more specifically, relates to a silicon-based integrated device and a measurement method for synchronous measurement of microwave frequency and angle of arrival. Background Art

[0002] With the rapid development of radar / communication technology, the microwave frequency bands used by modern electronic information devices are becoming wider and the dynamics are continuously increasing. The future technological development has put forward higher standards for the measurement of microwave signals. On the one hand, the measurement tasks have expanded from the two basic parameters of traditional frequency and amplitude to the measurement of multi-dimensional parameters including frequency, amplitude, phase, signal type, angle of arrival, and time of arrival; on the other hand, the operating frequency range continues to increase, almost covering the frequency band from 2 MHz to 300 GHz. However, traditional electronic frequency measurement schemes usually can only cover up to 18 GHz and can no longer meet the new requirements. These technical bottlenecks urgently require new solutions.

[0003] Microwave photonics technology combines the advantages of microwaves and photonics. By using photon technology to generate, transmit, and process microwave signals, it exhibits significant characteristics such as large instantaneous bandwidth, light weight, low loss, and strong anti-electromagnetic interference ability. This technology has been widely used in fields such as radar, satellite communication, and information technology, and at the same time provides a new solution path for the measurement of microwave signal frequency and angle of arrival. In recent years, much progress has been made in the research on the measurement of microwave signal frequency and angle of arrival based on microwave photonics technology, and the relevant results have been widely reported. The existing microwave frequency measurement methods mainly include three types: frequency-amplitude mapping, frequency-space mapping, and frequency-time domain mapping. These methods indirectly infer the frequency parameter by converting the frequency information of the microwave signal into power or time information. Among them, frequency-amplitude mapping has attracted much attention due to its simple design and high accuracy. However, the existing schemes usually rely on a single optical filter and it is difficult to simultaneously achieve a wide measurement bandwidth and high measurement accuracy. In addition, there is currently no device that can simultaneously measure frequency and angle of arrival.

[0004] Therefore, the prior art lacks a chip-integrated, lightweight, low-power, and powerful microwave frequency and angle of arrival measurement scheme. Summary of the Invention

[0005] Aiming at the problems existing in the background art, the object of the present invention is to provide a device and method for measuring microwave frequency and angle of arrival by using a dual-parallel Mach-Zehnder modulator, aiming to solve the technical problem of synchronous measurement of frequency and angle of arrival of radar microwave signals under high-precision and large-bandwidth conditions, and solve the technical problem of simultaneous measurement of microwave frequency and angle of arrival with chip integration, light weight, low power consumption, and powerful functions.

[0006] The technical solution adopted by the present invention is as follows: 1. A silicon-based integrated device for synchronous measurement of microwave frequency and angle of arrival: It includes two radar antennas arranged at intervals, connected to the electrical modulation terminals of a dual-parallel Mach-Zehnder electro-optic intensity modulator, for receiving an external microwave signal to be measured and sending it to the dual-parallel Mach-Zehnder electro-optic intensity modulator; It includes a dual-parallel Mach-Zehnder electro-optic intensity modulator, for receiving an optical carrier input from an external light source and loading the microwave signal to be measured of the radar antenna onto the optical carrier, thereby generating two optical carrier microwave signals and sending them to a measurement unit for synchronous measurement of microwave frequency and angle of arrival; It includes a first instantaneous frequency measurement unit, an angle of arrival measurement unit, and a second instantaneous frequency measurement unit, connected to the output terminals of the dual-parallel Mach-Zehnder electro-optic intensity modulator, respectively used for rough measurement of the frequency of the optical carrier microwave signal, measurement of the angle of arrival, and fine measurement of the frequency.

[0007] The device structure of the present invention is based on an optical waveguide structure. The first instantaneous frequency measurement unit, the angle of arrival measurement unit, and the second instantaneous frequency measurement unit are all similar waveguide structures, but they are not the same.

[0008] The dual-parallel Mach-Zehnder electro-optic intensity modulator is mainly composed of two Mach-Zehnder electro-optic intensity modulators. Each Mach-Zehnder electro-optic intensity modulator is provided with two output terminals. The four output terminals of the two Mach-Zehnder electro-optic intensity modulators are combined into one output terminal and connected to the angle of arrival measurement unit, and the remaining two output terminals are respectively connected to the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit.

[0009] In the dual-parallel Mach-Zehnder electro-optic intensity modulator, a Y-branch is provided at the output terminal of each Mach-Zehnder electro-optic intensity modulator to divide each optical carrier microwave signal output by itself into two paths with uniform intensity. The two Mach-Zehnder electro-optic intensity modulators altogether form four optical carrier microwave signals. Among them, two optical carrier microwave signals are respectively input to the first and second frequency measurement units, and the other two are combined and input to the angle of arrival measurement unit.

[0010] The two Mach-Zehnder electro-optic intensity modulators respectively process optical carrier microwave signals with different phases.

[0011] The double parallel Mach-Zehnder optoelectronic intensity modulator includes a first Mach-Zehnder optoelectronic intensity modulator, a second Mach-Zehnder optoelectronic intensity modulator, a thermal electrode, a first Y-branch, and a second Y-branch; the input ends of the first Mach-Zehnder optoelectronic intensity modulator and the second Mach-Zehnder optoelectronic intensity modulator are used to connect to a light source after passing through an input Y-branch, and the output ends of the first Mach-Zehnder optoelectronic intensity modulator and the second Mach-Zehnder optoelectronic intensity modulator are each divided into two output ends via the first Y-branch and the second Y-branch respectively. One branch end of each of the first Y-branch and the second Y-branch is respectively connected to a first instantaneous frequency measurement unit and a second instantaneous frequency measurement unit, and the other branch ends of the first Y-branch and the second Y-branch are combined into one path / one end and connected to an arrival angle measurement unit; the input Y-branch at the output end of the Mach-Zehnder optoelectronic intensity modulator divides each output optical carrier microwave signal into two paths with uniform intensity. The two Mach-Zehnder optoelectronic intensity modulators output a total of four optical carrier microwave signals, where two optical carrier microwave signals are respectively input to the first and second frequency measurement units, and the other two are combined at the combined branch end and input to the arrival angle measurement unit; near the collective end of one of the first Y-branch and the second Y-branch, a thermal electrode is provided, and a voltage is applied to the thermal electrode to heat-modulate the phase of the optical carrier microwave signal passing through the Y-branch.

[0012] Each of the radar antennas receives a microwave signal to be measured of an external object to be measured from the three-dimensional space, and the two radar antennas are electrically connected to the traveling wave electrodes of the two Mach-Zehnder optoelectronic intensity modulators, and the two received microwave signals to be measured with a phase difference are respectively loaded and modulated onto the optical carriers.

[0013] Each of the measurement units includes a thermally tunable microring resonator, an unequal-arm Mach-Zehnder interferometer, and two detection modules; the input end of the unequal-arm Mach-Zehnder interferometer is connected to an output end of the double parallel Mach-Zehnder optoelectronic intensity modulator via a waveguide, a thermally tunable microring resonator is provided beside the waveguide at the input end of the unequal-arm Mach-Zehnder interferometer, the two output ends of the unequal-arm Mach-Zehnder interferometer are respectively connected to the two detection modules, and delay lines, thermal electrodes, or microrings are provided on the interference arms inside the unequal-arm Mach-Zehnder interferometer.

[0014] The first instantaneous frequency measurement unit includes a first thermally tunable microring resonator, a first unequal-arm Mach-Zehnder interferometer, a first detection module, and a second detection module; the input end of the first unequal-arm Mach-Zehnder interferometer is connected to the first output end of the double parallel Mach-Zehnder optoelectronic intensity modulator via a waveguide, a first thermally tunable microring resonator is provided beside the waveguide at the input end of the first unequal-arm Mach-Zehnder interferometer, the two output ends of the first unequal-arm Mach-Zehnder interferometer are respectively connected to the first detection module and the second detection module, and a delay line and a thermal electrode are respectively provided on the two interference arms inside the first unequal-arm Mach-Zehnder interferometer; The second instantaneous frequency measurement unit includes a third thermally tunable microring resonator, a second unbalanced Mach-Zehnder interferometer, a fifth detection module, and a sixth detection module; the input end of the second unbalanced Mach-Zehnder interferometer is connected to the second output end of the dual-parallel Mach-Zehnder electro-optic intensity modulator through a waveguide, a third thermally tunable microring resonator is arranged beside the waveguide at the input end of the second unbalanced Mach-Zehnder interferometer, the two output ends of the second unbalanced Mach-Zehnder interferometer are respectively connected to the fifth detection module and the sixth detection module, and delay lines and thermal electrodes are respectively arranged on the two interference arms inside the first unbalanced Mach-Zehnder interferometer; The arrival angle measurement unit includes a second thermally tunable microring resonator, a microring-assisted unbalanced Mach-Zehnder interferometer, a third detection module, and a fourth detection module; the input end of the microring-assisted unbalanced Mach-Zehnder interferometer is connected to the third output end of the dual-parallel Mach-Zehnder electro-optic intensity modulator through a waveguide, a second thermally tunable microring resonator is arranged beside the waveguide at the input end of the microring-assisted unbalanced Mach-Zehnder interferometer, the two output ends of the microring-assisted unbalanced Mach-Zehnder interferometer are respectively connected to the third detection module and the fourth detection module, delay lines and microrings are respectively arranged on the two interference arms inside the microring-assisted unbalanced Mach-Zehnder interferometer, a thermal electrode is arranged beside the input waveguide beside the delay line, and a thermal electrode is arranged beside the microring; The lengths of the delay lines of the second instantaneous frequency measurement unit are all greater than those of the delay lines of the first instantaneous frequency measurement unit and the arrival angle measurement unit; the sizes of the thermally tunable microring resonators of the first instantaneous frequency measurement unit, the second instantaneous frequency measurement unit, and the arrival angle measurement unit are the same, and each thermally tunable microring resonator is provided with a thermal electrode.

[0015] The arrival angle described in the present invention is a planar angle or a solid angle.

[0016] The first detection module, the second detection module, the third detection module, the fourth detection module, the fifth detection module, and the sixth detection module are photodetectors or vertical coupling gratings.

[0017] II. A method for synchronously measuring microwave frequency and arrival angle, the method simultaneously measures microwave frequency and arrival angle, specifically: II. A method for measuring high-precision and large-bandwidth microwave frequency: In order to achieve high-precision and large-bandwidth microwave frequency measurement, the present invention provides a silicon-based integrated microwave frequency measuring instrument, which includes a microwave source, a multi-path programmable voltage source, a multi-channel oscilloscope, and a 1550 nm tunable laser. The tunable laser is arranged as a light source at the input end of the silicon-based integrated device, and the multi-path programmable voltage source and the multi-channel oscilloscope are both connected to the silicon-based integrated device. The multi-channel oscilloscope uses a multi-channel low-speed oscilloscope.

[0018] At this time, the silicon-based integrated device for frequency measurement only includes a first Mach-Zehnder photoelectric intensity modulator, a second Mach-Zehnder photoelectric intensity modulator, an input Y-branch, a first instantaneous frequency measurement unit, a second instantaneous frequency measurement unit, a microwave source, which is connected to each traveling-wave electrode of the first Mach-Zehnder photoelectric intensity modulator and the second Mach-Zehnder photoelectric intensity modulator, a multi-path programmable voltage source, which is connected to each thermal electrode of the first instantaneous frequency measurement unit, the second instantaneous frequency measurement unit, and the thermal electrodes of the Mach-Zehnder photoelectric intensity modulator, and a multi-channel oscilloscope, which is connected to each detector of the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit in the silicon-based integrated device.

[0019] In a specific implementation, the microwave measuring instrument of the present invention is provided with an optical carrier by an external 1550 tunable single-wavelength laser 5.

[0020] Step 1: Connect the silicon-based integrated device as an optical chip to a tunable laser, a radar antenna, a multi-channel oscilloscope, and a multi-path programmable voltage source respectively; the 1550 nm tunable laser is used as a light source.

[0021] Step 2: Turn on the tunable laser to emit a calibrated optical carrier of 1550 nm and divide the optical carrier into two paths with equal intensity through the Y-branch, and send them into the first Mach-Zehnder photoelectric intensity modulator and the second Mach-Zehnder photoelectric intensity modulator respectively to form two optical carrier microwave signals of the calibrated optical carrier, and adjust the bias voltage to make the first and second Mach-Zehnder photoelectric intensity modulators work at the minimum bias point to form a carrier suppression modulation format. Step 3: After the first optical carrier microwave signal is divided into two paths with equal amplitude through the first Y-branch, one path enters the first instantaneous frequency measurement unit. After the second optical carrier microwave signal is divided into two paths with equal amplitude through the second Y-branch, one path enters the second instantaneous frequency measurement unit. Step 4: Use the multi-channel voltage source to control the thermally tunable microring resonators in the first and second instantaneous frequency measurement units, specifically the thermally tunable microring resonators laid at the microring and the waveguide of the unequal-arm Mach-Zehnder interferometer, so that they work in the required working state, that is, the center wavelength of their operation is the same as the wavelength of the optical carrier. Step 5: Use a microwave source to perform frequency sweeping within the operating range of the frequency meter to control the frequency of the optically carried microwave signal, and record the output powers of the two output signals of the first and second instantaneous frequency measurement units respectively through a multi-channel oscilloscope. Subsequently, divide and compare the output powers of the two output signals of each instantaneous frequency measurement unit at each input microwave signal frequency during frequency sweeping to obtain a power ratio. For each instantaneous frequency measurement unit, fit and establish the relationship between the input microwave signal frequency of different frequency sweeps and the corresponding power ratio to obtain a comparison function relationship, thus completing the calibration work; obtain the relationship between the microwave frequency and the output power of the instantaneous frequency measurement unit through the amplitude comparison function.

[0022] Step 6: Input the microwave signal to be measured into the first and second Mach-Zehnder electro-optic intensity modulators to obtain the first and second optically carried microwave signals of the microwave signal to be measured respectively, and then input them into the first and second instantaneous frequency measurement units respectively, and record the real-time output powers of the first and second instantaneous frequency measurement units respectively through a multi-channel oscilloscope. Step 7: Substitute the real-time output powers into the respective comparison function relationships of the first and second instantaneous frequency measurement units for calculation to obtain the measured frequency of the microwave signal to be measured. In the said Step 5, a bias voltage is applied through a voltage source to change the frequency of the microwave signals input to the first and second Mach-Zehnder electro-optic intensity modulators, so as to establish the relationship between the power ratio of the two output powers of the first and second instantaneous measurement units respectively and the input signal frequency and fit and construct a comparison function relationship. The power ratio is expressed by the formula: ACF = P up / P down = tan 2 (πn g ΔL / λ) P up = sin 2 (πn g ΔL / λ)E 2 P down = cos 2 (πn g ΔL / λ)E 2 Wherein, ACF is the power ratio, n g is the group refractive index of the fundamental mode in the waveguide of the silicon-based optical chip, ΔL is the length difference between the upper and lower two interference arms of the unbalanced Mach-Zehnder interferometer, λ is the optical wavelength input to the unbalanced Mach-Zehnder interferometer, and λ is converted to reflect the frequency. E 2 is the amplitude when the optically carried microwave signal enters the unbalanced Mach-Zehnder interferometer, and P up , P down are the output powers of the two output ends of the unbalanced Mach-Zehnder interferometer respectively.

[0023] In specific implementation, applying a bias voltage and inputting a microwave signal are not performed by the same device. A microwave source is used to generate the input microwave signal, and a voltage source is used to apply the bias voltage.

[0024] In step 7, after obtaining the measured frequencies of the microwave signals to be measured obtained by the first and second instantaneous frequency measurement units respectively, since the first instantaneous frequency measurement unit performs a rough measurement and its result is only a roughly estimated result, while the second instantaneous frequency measurement unit performs an accurate measurement and its result has several accurate results, the measured frequency of the microwave signal to be measured obtained corresponding to the first instantaneous frequency measurement unit is used as the reference measurement frequency, and the one closest to the reference measurement frequency is found among the several measured frequencies of the microwave signals to be measured obtained corresponding to the second instantaneous frequency measurement unit as the final accurate measurement frequency.

[0025] III. A method for measuring the arrival angle of a high-precision radar microwave signal: In order to achieve large-range and high-precision measurement of the arrival angle of radar signals, an arrival angle measurement unit is further additionally added to form an arrival angle measuring instrument, and the respective thermal electrodes of the arrival angle measurement unit are connected to a multi-path programmable voltage source.

[0026] Step 8: The radar signals received by two radar antennas within a range of one microwave signal wavelength are respectively connected to a first and a second Mach-Zehnder electro-optical intensity modulator to form a first and a second optical carrier microwave signal of the microwave signal to be measured respectively. The radar antennas use the wavelength of the microwave signal, in millimeters or centimeters. This enables the distance between the two radar antennas to reach the optical wavelength range and be at the mm level.

[0027] Based on step 3, after the first optical carrier microwave signal and the second optical carrier microwave signal are respectively divided into two optical signals with equal amplitudes by the first Y-branch and the second Y-branch, one path is taken from each and combined to form a dual-parallel Mach-Zehnder intensity modulator, and then it is sent to the arrival angle measurement unit. Step 9: The arrival angle measurement unit receives the optical carrier microwave signal output by the Mach-Zehnder electro-optical intensity modulator, divides it into two parts of the upper and lower sidebands, and outputs them respectively. After passing through photodetectors, they are input into a multi-channel oscilloscope. In the arrival angle measurement unit, a micro-ring-assisted unbalanced Mach-Zehnder interferometer is used to divide the optical carrier microwave signal output by the Mach-Zehnder electro-optical intensity modulator into two parts centered on the optical carrier according to the wavelength, which are used as the upper and lower sidebands respectively.

[0028] Step 10: Adjust the thermally tunable microring resonator laid at one-arm waveguide of the dual-parallel Mach-Zehnder electro-optic intensity modulator, change the phase difference between the upper and lower sidebands of the optical carrier microwave signals output from the two arms, and obtain the arrival angle of the radar microwave signal by recording the waveforms on the multi-channel oscilloscope.

[0029] In the said Step 5, by applying a bias voltage through the microwave source to change the microwave signal frequencies input to the first and second Mach-Zehnder electro-optic intensity modulators, respectively establish the relationship between the power ratio of the two output powers of each of the two paths of the first and second instantaneous measurement units and the input signal frequency and fit to construct a comparison function relationship. The power ratio is expressed by the formula: ACF = P up / P down = tan 2 (πn g ΔL / λ) P up = sin 2 (πn g ΔL / λ)E 2 P down = cos 2 (πn g ΔL / λ)E 2 Wherein, ACF is the power ratio, n g is the group refractive index of the fundamental mode in the waveguide of the silicon-based optical chip, ΔL is the length difference between the upper and lower two interference arms of the unbalanced Mach-Zehnder interferometer, λ is the optical wavelength input to the unbalanced Mach-Zehnder interferometer, and is reflected as the frequency by λ conversion. E 2 is the amplitude when the optical carrier microwave signal enters the unbalanced Mach-Zehnder interferometer, and P up 、P down are the output powers of the two output ends of the unbalanced Mach-Zehnder interferometer respectively.

[0030] In the said Step 7, after obtaining the measurement frequencies of the microwave signals to be measured obtained by the first and second instantaneous frequency measurement units respectively, since the first instantaneous frequency measurement unit conducts a rough measurement and its result is only a roughly estimated result, and the second instantaneous frequency measurement unit conducts an accurate measurement and its result has several accurate results, therefore, take the measurement frequency of the microwave signal to be measured obtained corresponding to the first instantaneous frequency measurement unit as the reference measurement frequency, and find the one closest to the reference measurement frequency among the several measurement frequencies of the microwave signal to be measured obtained corresponding to the second instantaneous frequency measurement unit as the final accurate measurement frequency.

[0031] In the said Step 10, the output power of the arrival angle measurement unit is a function of the phase difference of the optical carrier microwave signals output from the two Mach-Zehnder electro-optic modulators of the dual-parallel Mach-Zehnder electro-optic intensity modulator, and is expressed as follows: P +1 = 2E0 2 J +1 2 (m)[1 + cos(β - α)] P -1 = 2E0 2 J -1 2 (m)[1 + cos(β + α)] Among them, P +1 is the sum of the output powers of the upper sideband, P -1 is the output power of the lower sideband, E0 is the amplitude of the input optical carrier, β is the phase difference caused by the distance difference between the two radar antennas, α is the phase difference of the optical-carried microwave signal, J n (m) represents the nth-order Bessel function and satisfies J -n (m)=(-1) n J n (m), m represents the independent variable of the Bessel function, usually corresponding to the spatial or frequency parameter in the physical problem; According to the above formula, by combining and inversely calculating the phase difference of the optical-carried microwave signal from the output powers of the upper and lower sidebands, the phase difference of the microwave signals received by the two antennas can be obtained, and then the time delay of the microwave signals received by the two radar antennas can be inferred based on the phase difference. Furthermore, the angle of arrival can be obtained through conversion calculation based on the radar spacing distance.

[0032] The dual-parallel Mach-Zehnder electro-optic intensity modulator of the present invention is used to load a microwave signal to be measured with a specific angle of arrival onto an optical carrier to generate two optical-carried microwave signals. Each signal is divided into two paths with uniform intensity through a Y-branch structure, forming a total of four optical-carried microwave signals. Two of them are respectively input into two frequency measurement units, and the other two are combined and then input into an angle-of-arrival measurement unit. The frequency measurement unit maps the frequency of the optical-carried microwave signal to a power value by providing two independent linear frequency responses, and accurately measures the frequency of the microwave signal through power detection. The angle-of-arrival measurement unit infers the relative phase of the two optical-carried microwave signals by detecting the power value of the output port, and then calculates the angle of arrival of the microwave signal.

[0033] The present invention adopts a single structure to achieve synchronous and efficient measurement of the frequency and angle of arrival of radar microwave signals, significantly improving the detection efficiency, and enhancing the practicability and application range of the system.

[0034] The beneficial effects of the present invention are: The silicon-based microwave frequency measuring instrument proposed by the present invention adopts two-stage unequal-arm Mach-Zehnder interferometers with different delay amounts, and realizes the complementary measurement performance by combining the preliminary measurement with large bandwidth and low precision and the fine measurement with small bandwidth and high precision, thus achieving a wide measurement range and high measurement precision of microwave frequency.

[0035] The silicon-based microwave detection scheme of the present invention can not only measure the frequency of microwave signals with high precision, but also synchronously achieve high-precision measurement of the arrival angle of microwave signals, greatly improving the functionality and practicality of the system.

[0036] By realizing the hybrid integration of modulators, detectors and thermal tuning devices, the present invention has remarkable characteristics such as high integration, light weight and low loss, providing strong support for constructing a high-performance silicon-based microwave detection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of the present invention; Figure 2 is an experimental device diagram of the present invention; Figure 3 is a schematic diagram of the transmission spectrum of the first frequency measurement unit 200 of the present invention and the obtained amplitude comparison function; Figure 4 is a schematic diagram of the transmission spectrum of the second frequency measurement unit 400 of the present invention and the obtained amplitude comparison function; Figure 5 is a schematic diagram of the output spectrum pattern of the arrival angle measurement unit 300 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] As Figure 1 shown, the device structure includes a dual-parallel Mach-Zehnder electro-optic intensity modulator, a first instantaneous frequency measurement unit 200, an arrival angle measurement unit 300 and a second instantaneous frequency measurement unit 400.

[0040] It may include a light source 5 for emitting an optical carrier to the input end of the dual-parallel Mach-Zehnder electro-optic intensity modulator.

[0041] It includes two radar antennas arranged at intervals, connected to the electrical modulation terminals of a dual-parallel Mach-Zehnder electro-optic intensity modulator, and is used to receive the microwave signal to be measured with a specific angle of arrival from the outside and send it to the dual-parallel Mach-Zehnder electro-optic intensity modulator 100.

[0042] It includes a dual-parallel Mach-Zehnder electro-optic intensity modulator 100, which is used to receive the optical carrier input from an external light source 5, load the microwave signal to be measured by the radar antenna onto the optical carrier to modulate the optical carrier, and then generate two optical carrier microwave signals and send them to three measurement units for synchronous measurement of microwave frequency and angle of arrival.

[0043] It includes a first instantaneous frequency measurement unit 200, an angle of arrival measurement unit 300, and a second instantaneous frequency measurement unit 400, which are optically connected to the output terminal of the dual-parallel Mach-Zehnder electro-optic intensity modulator 100 and are respectively used for relatively rough measurement of the frequency of the optical carrier microwave signal, measurement of the angle of arrival, and relatively fine measurement of the frequency.

[0044] The dual-parallel Mach-Zehnder electro-optic intensity modulator 100 is mainly composed of two Mach-Zehnder electro-optic intensity modulators arranged in parallel. Each Mach-Zehnder electro-optic intensity modulator is provided with two output terminals. The four output terminals of the two Mach-Zehnder electro-optic intensity modulators are combined into one output terminal and connected to the angle of arrival measurement unit 300, and the other two output terminals are respectively connected to the first instantaneous frequency measurement unit 200 and the second instantaneous frequency measurement unit 400, so that a total of three output terminals are formed as a whole.

[0045] The dual-parallel Mach-Zehnder electro-optic intensity modulator 100 includes a first Mach-Zehnder electro-optic intensity modulator 110, a second Mach-Zehnder electro-optic intensity modulator 120, a thermal electrode 101, a first Y-branch 102, and a second Y-branch 103; the first Mach-Zehnder electro-optic intensity modulator 110 and the second Mach-Zehnder electro-optic intensity modulator 120 are arranged in parallel. The input terminals of the first Mach-Zehnder electro-optic intensity modulator 110 and the second Mach-Zehnder electro-optic intensity modulator 120 are used to connect to the light source 5 after passing through an input Y-branch. More specifically, the input terminals of the first Mach-Zehnder electro-optic intensity modulator 110 and the second Mach-Zehnder electro-optic intensity modulator 120 are both connected to the two branch ends of the Y-branch, and the collective end of the Y-branch serves as the input terminal of the dual-parallel Mach-Zehnder electro-optic intensity modulator 100 to receive the light source 5.

[0046] The output ends of the first Mach-Zehnder optoelectronic intensity modulator 110 and the second Mach-Zehnder optoelectronic intensity modulator 120 are each divided into two output ends via a first Y-branch 102 and a second Y-branch 103 respectively. More specifically, the input ends of the first Mach-Zehnder optoelectronic intensity modulator 110 and the second Mach-Zehnder optoelectronic intensity modulator 120 are respectively connected to the collective ends of the first Y-branch 102 and the second Y-branch 103, and the two branch ends of each of the first Y-branch 102 and the second Y-branch 103 are used to connect to a measurement unit.

[0047] One of the branch ends of each of the first Y-branch 102 and the second Y-branch 103 is respectively connected to a first instantaneous frequency measurement unit 200 and a second instantaneous frequency measurement unit 400, and the other branch ends of the first Y-branch 102 and the second Y-branch 103 are combined into one path / one end and connected to an angle-of-arrival measurement unit 300. Near the collective end of one of the first Y-branch 102 and the second Y-branch 103, there is a thermal electrode 101 for modulation. A voltage is applied to the thermal electrode 101 to heat-modulate the phase of the optical carrier microwave signal passing through the Y-branch, performing a phase-shifting function.

[0048] The input Y-branch at the output end of the Mach-Zehnder optoelectronic intensity modulator divides each optical carrier microwave signal output by the Mach-Zehnder optoelectronic intensity modulator into two paths with uniform intensity. The two Mach-Zehnder optoelectronic intensity modulators altogether output four optical carrier microwave signals. Among them, two optical carrier microwave signals are respectively input into the first and second frequency measurement units 200 and 400, and the other two are combined at the combined branch end and input into the angle-of-arrival measurement unit 300; Inside each Mach-Zehnder optoelectronic intensity modulator, there are two interference arms, and traveling-wave electrodes are arranged on each interference arm and between the two interference arms.

[0049] The first and second Mach-Zehnder optoelectronic intensity modulators are used to load the microwave signals to be measured with a certain phase difference received by two radar antennas onto an optical carrier, forming an optical carrier microwave signal, and retaining the phase difference information of the microwave signals.

[0050] In a specific implementation, a thermal electrode 101 is arranged beside the first Y-branch 102, such that the first Y-branch 102 has a phase-shifting function; a non-thermal electrode is arranged beside the second Y-branch 103, such that the first Y-branch 102 does not have a phase-shifting function. The thermal electrode 101 is placed beside one of the Y-branches, and it can be used to adjust the output phase of any one of the Mach-Zehnder optoelectronic modulators in the dual-parallel Mach-Zehnder optoelectronic modulator, thereby realizing the adjustment of the output sideband power.

[0051] The silicon-based integrated device of the present invention is used to measure the frequency and azimuth of radar microwave signals. Each radar antenna is arranged at intervals and faces the three-dimensional space, and respectively receives the microwave signals to be measured of an external object to be measured from the three-dimensional space. Two radar antennas are electrically connected to the traveling-wave electrodes of two Mach-Zehnder electro-optic intensity modulators. Since the two radar antennas are arranged at intervals, the microwave signals to be measured received by the two radar antennas have a phase difference, and the two received microwave signals to be measured with a phase difference are respectively loaded and modulated onto their corresponding optical carriers.

[0052] The frequency measurement unit maps the frequency of the optical carrier microwave signal into a power value by providing two independent linear frequency responses, and accurately measures the frequency of the microwave signal through power detection; specifically, it is divided into a first instantaneous frequency measurement unit and a second instantaneous frequency measurement unit: among them, the first instantaneous frequency measurement unit roughly measures the frequency of an unknown microwave signal over a large range by detecting the output power, and it has the characteristics of a large measurement range and good real-time performance; the second instantaneous measurement unit finely measures the frequency information of the unknown microwave signal by detecting the output power, and it has the characteristics of high accuracy and good real-time performance.

[0053] The angle of arrival measurement unit infers the relative phase of the two optical carrier microwave signals by detecting the power value at the output port, and then calculates the arrival angle of the microwave signal.

[0054] Each measurement unit includes a thermally tunable microring resonator, an unbalanced Mach-Zehnder interferometer, and two detection modules; the input end of the unbalanced Mach-Zehnder interferometer is connected to an output end of a dual-parallel Mach-Zehnder electro-optic intensity modulator through a waveguide, a thermally tunable microring resonator is arranged beside the waveguide at the input end of the unbalanced Mach-Zehnder interferometer, the two output ends of the unbalanced Mach-Zehnder interferometer are respectively connected to the two detection modules, and a delay line, a thermal electrode or a microring is arranged on the interference arms inside the unbalanced Mach-Zehnder interferometer.

[0055] The first instantaneous frequency measurement unit 200 includes a first thermally tunable microring resonator 201, a first unbalanced Mach-Zehnder interferometer 210, a first detection module 202 and a second detection module 203; the input end of the first unbalanced Mach-Zehnder interferometer 210 is connected to the first output end of a dual-parallel Mach-Zehnder electro-optic intensity modulator 100 through a waveguide, that is, it is connected to one branch end of the first Y-branch 102 at the output end of the first Mach-Zehnder electro-optic intensity modulator 110 of the dual-parallel Mach-Zehnder electro-optic intensity modulator 100; a first thermally tunable microring resonator 201 is arranged beside the waveguide at the input end of the first unbalanced Mach-Zehnder interferometer 210, the two output ends of the first unbalanced Mach-Zehnder interferometer 210 are respectively connected to the first detection module 202 and the second detection module 203, and a delay line 211 and a thermal electrode 212 are respectively arranged on the two interference arms inside the first unbalanced Mach-Zehnder interferometer 210.

[0056] The delay line 211 is used to change the delay of the two arms of the Mach-Zehnder interferometer 210, so that the output waveform changes periodically according to the sine function type. The thermal electrode 212 is used to finely adjust the delay of the two arms of the Mach-Zehnder interferometer 210 and regulate the central wavelength of the output waveform. A fixed voltage value is loaded on the first thermally tunable microring 201 to accurately adjust the central wavelength of the microring, which is used to filter out the optical carrier and only retain the optical carrier microwave signal after microwave signal modulation, improving the measurement frequency accuracy.

[0057] The second instantaneous frequency measurement unit 400 includes a third thermally tunable microring resonator 401, a second unbalanced Mach-Zehnder interferometer 410, a fifth detection module 402, and a sixth detection module 403; the input end of the second unbalanced Mach-Zehnder interferometer 410 is connected to the second output end of the dual-parallel Mach-Zehnder electro-optic intensity modulator 100 through a waveguide, that is, connected to one branch end of the second Y-branch 103 at the output end of the second Mach-Zehnder electro-optic intensity modulator 120 of the dual-parallel Mach-Zehnder electro-optic intensity modulator 100; a third thermally tunable microring resonator 401 is arranged beside the waveguide at the input end of the second unbalanced Mach-Zehnder interferometer 410, the two output ends of the second unbalanced Mach-Zehnder interferometer 410 are respectively connected to the fifth detection module 402 and the sixth detection module 403, and a delay line 411 and a thermal electrode 412 are respectively arranged on the two interference arms inside the first unbalanced Mach-Zehnder interferometer 210.

[0058] The delay line 411 is used to change the delay of the two arms of the Mach-Zehnder interferometer 410, so that the output waveform changes periodically according to the sine function type. The difference from the delay line 211 is that the changed delay amount is different, making the output spectrum period smaller. The thermal electrode 412 is used to finely adjust the delay of the two arms of the Mach-Zehnder interferometer 410 and regulate the central wavelength of the output waveform. A fixed voltage value is loaded on the second thermally tunable microring 401, which is used to filter out the optical carrier and improve the measurement frequency accuracy.

[0059] The arrival angle measurement unit 300 includes a second thermally tunable microring resonator 301, a microring-assisted unbalanced Mach-Zehnder interferometer 310, a third detection module 302, and a fourth detection module 303; the input end of the microring-assisted unbalanced Mach-Zehnder interferometer 310 is connected to the third output end of the dual-parallel Mach-Zehnder electro-optic intensity modulator 100 through a waveguide, a second thermally tunable microring resonator 301 is arranged beside the waveguide at the input end of the microring-assisted unbalanced Mach-Zehnder interferometer 310, the two output ends of the microring-assisted unbalanced Mach-Zehnder interferometer 310 are respectively connected to the third detection module 302 and the fourth detection module 303, a delay line 311 and a microring 312 are respectively arranged on the two interference arms inside the microring-assisted unbalanced Mach-Zehnder interferometer 310, a thermal electrode 314 is arranged beside the input waveguide beside the delay line 311, and a thermal electrode 313 is arranged beside the microring 312.

[0060] The delay line 311 is used to change the delay of the two arms of the Mach-Zehnder interferometer 410. The microring 312 is used to form a microring-assisted unbalanced Mach-Zehnder interferometer 310 to adjust the output spectrum. The thermal electrode 314 is used to finely control the delay of the two arms of the Mach-Zehnder interferometer 410 and regulate the central wavelength of the output waveform. The thermal electrode 313 is used to adjust the optical path length of the microring, regulate the central wavelength of the microring output, change the delay of the light output from the two arms, and thus change the output spectrum of the microring-assisted unbalanced Mach-Zehnder interferometer. A fixed voltage value is loaded on the second thermally tunable microring 301 to filter out the optical carrier and improve the measurement frequency accuracy.

[0061] The microring-assisted unbalanced Mach-Zehnder interferometer 310 is used for wavelength division multiplexing. It uses a 1×2 structure to output the upper and lower first-order sidebands of the dual-parallel Mach-Zehnder photoelectric modulator at the two outputs respectively.

[0062] The microring 312 uses a narrowband large free spectral range band-stop filter with a Q value of 10 6 , and the free spectral range is 1 nm. Its central wavelength and extinction ratio can be adjusted by the thermal electrodes on the microring.

[0063] The first unbalanced Mach-Zehnder interferometer has a 2×2 asymmetric Mach-Zehnder interferometer structure with a free spectral range FSR of 100 GHz, which can realize the mapping relationship between microwave frequencies and output powers in a large range with low precision.

[0064] The second unbalanced Mach-Zehnder interferometer has a 2×2 asymmetric Mach-Zehnder interferometer structure with a free spectral range of 20 GHz, which can realize the mapping of microwave frequencies and output powers with high precision in a small range.

[0065] When the second instantaneous frequency measurement unit is used complementarily with the first instantaneous measurement module, the system can maintain a large measurement range while having relatively high measurement accuracy.

[0066] Both Mach-Zehnder photoelectric intensity modulators operate at the minimum bias point to generate a carrier-suppressed double-sideband optical carrier microwave signal.

[0067] The length of the delay line 411 of the second instantaneous frequency measurement unit 400 is greater than that of the delay line 211 of the first instantaneous frequency measurement unit 200 and the delay line 311 of the arrival angle measurement unit 300. The delay line 211 of the first instantaneous frequency measurement unit 200 and the delay line 311 of the arrival angle measurement unit 300 are about the same; The sizes of the thermal tuning microring resonators of the first instantaneous frequency measurement unit 200, the second instantaneous frequency measurement unit 400, and the angle of arrival measurement unit 300 are the same, and each thermal tuning microring resonator is provided with a thermal electrode; that is, the sizes of the first thermal tuning microring resonator 201 of the first instantaneous frequency measurement unit 200, the third thermal tuning microring resonator 401 of the second instantaneous frequency measurement unit 400, and the second thermal tuning microring resonator 301 of the angle of arrival measurement unit 300 are the same, and are respectively provided with a thermal electrode 204, a thermal electrode 404, and a thermal electrode 304.

[0068] The first detection module, the second detection module, the third detection module, the fourth detection module, the fifth detection module, and the sixth detection module are photodetectors or vertical coupling gratings.

[0069] In the examples of the present invention, the specific radar signal microwave frequency and the scheme principle and examples of angle of arrival measurement include the following steps: First, design a silicon-based integrated microwave frequency measuring instrument, including a microwave source, a multi-path programmable voltage source, a multi-channel oscilloscope, and a 1550 nm tunable laser. The tunable laser is arranged as a light source 5 at the input end of the silicon-based integrated device, and the multi-path programmable voltage source and the multi-channel oscilloscope are both connected to the silicon-based integrated device. The multi-channel oscilloscope uses a multi-channel low-speed oscilloscope.

[0070] For frequency measurement, the silicon-based integrated device at this time only includes a first Mach-Zehnder electro-optic intensity modulator, a second Mach-Zehnder electro-optic intensity modulator, an input Y-branch, a first instantaneous frequency measurement unit, and a second instantaneous frequency measurement unit. The microwave source is connected to each traveling-wave electrode of the first Mach-Zehnder electro-optic intensity modulator and the second Mach-Zehnder electro-optic intensity modulator. The multi-path programmable voltage source is connected to each thermal electrode of the first instantaneous frequency measurement unit, the second instantaneous frequency measurement unit, and the thermal electrode 101 of the Mach-Zehnder electro-optic intensity modulator. The multi-channel oscilloscope is connected to each detector of the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit in the silicon-based integrated device.

[0071] In specific implementation, the microwave measuring instrument of the present invention is provided with an optical carrier by an external 1550 tunable single-wavelength laser 5.

[0072] Step 1: As Figure 2 shown, connect the silicon-based integrated optical chip to a 1550 nm tunable laser, a vector network analyzer, a multi-channel oscilloscope, and a multi-path programmable voltage source respectively. Among them, the 1550 nm tunable laser outputs an optical carrier, and the optical wave angular frequency is denoted as ω c , the amplitude is denoted as E0, the initial phase is φ, and the continuous optical wave is input into the dual-parallel Mach-Zehnder modulator. Among them, the optical carrier can be expressed as: E in (t) = E0exp[j(ωc (t) + φ)] Among them, E in (t) represents the optical carrier amplitude, exp[] represents the exponential function with the natural constant e (approx. 2.71828) as the base, j represents the imaginary unit, and t represents time (s).

[0073] Step 2: Use a vector network analyzer to simulate the radar signal to be measured received by the radar antenna, and divide the microwave signal into two paths with equal amplitudes. One path is directly input into the first Mach-Zehnder electro-optic intensity modulator without passing through a phase shifter, and the other path passes through a phase shifter to simulate the microwave phase difference caused by the difference in the position of the radar antenna, and then is input into the second Mach-Zehnder intensity modulator. Moreover, both Mach-Zehnder intensity modulators are controlled by a voltage source to operate at the minimum bias point. Among them, the amplitude of the input microwave signal at time t is V0, and the frequency is ω RF . The microwave signal at time t can be expressed as: V RF (t) = V0cos(ω RF (t) + θ) Among them, θ represents the phase difference between the two arms of the Mach-Zehnder electro-optic intensity modulator caused by the DC bias voltage.

[0074] Step 3: The first and second optical carrier microwave signals are respectively connected to the first and second instantaneous frequency measurement units after passing through Y-branches.

[0075] Specifically, after the first optical carrier microwave signal is divided into two paths with equal amplitudes by the first Y-branch 102, one path enters the first instantaneous frequency measurement unit; after the second optical carrier microwave signal is divided into two paths with equal amplitudes by the second Y-branch 103, one path enters the second instantaneous frequency measurement unit.

[0076] Step 4: Adjust its central wavelength to optimize the measurement performance.

[0077] Specifically, by applying different voltages to the thermal electrode 204 of the first thermally tunable microring 201 and the thermal electrode 404 of the third thermally tunable microring 401, the resonant wavelength of the microring is aligned with the optical carrier wavelength, thereby further filtering out the optical carrier and reducing its interference with subsequent measurements. By applying voltages to the thermal electrode 212 in the first unbalanced Mach-Zehnder interferometer 210 and the thermal electrode 412 in the second unbalanced Mach-Zehnder interferometer 410, the working central wavelength of the filtering response is accurately aligned with the optical carrier wavelength.

[0078] It should be noted that the length of the delay line 211 in the first unbalanced Mach-Zehnder interferometer is different from the length of the delay line 411 in the second unbalanced Mach-Zehnder interferometer, so their filtering response periods are also different.

[0079] In this example, the free spectral range of the first unbalanced Mach-Zehnder interferometer is 100 GHz, while that of the second unbalanced Mach-Zehnder interferometer is 20 GHz. This difference in the free spectral range provides technical support for achieving high-precision and wide-range frequency measurements.

[0080] Step 5: Use a vector network analyzer as a microwave source to sweep the input signal frequency of the control optical carrier within the operating range of the frequency meter, and record the output powers of the two output signals of the first and second instantaneous frequency measurement units 200 and 400 respectively through a multi-channel oscilloscope. Subsequently, divide and compare the output powers of the two output signals of each instantaneous frequency measurement unit at each swept input signal frequency to obtain a power ratio. For each instantaneous frequency measurement unit, fit and establish the relationship between the swept input signal frequencies and the corresponding power ratios to obtain a comparison function relationship, thus completing the calibration work; obtain the relationship between the microwave frequency and the output power of the instantaneous frequency measurement unit through the amplitude comparison function.

[0081] Apply a bias voltage through the microwave source to change the microwave signal frequencies input to the first and second Mach-Zehnder electro-optic intensity modulators 110 and 210, respectively, to establish the relationship between the power ratio of the two output powers of the first and second instantaneous measurement units 200 and 400 and the input signal frequency, and fit and construct a comparison function relationship. The power ratio is expressed by the formula: ACF = P up / P down = tan 2 (πn g ΔL / λ) P up = sin 2 (πn g ΔL / λ)E 2 P down = cos 2 (πn g ΔL / λ)E 2 Among them, ACF is the power ratio, n g is the group refractive index of the fundamental mode in the waveguide of the silicon-based optical chip, ΔL is the length difference between the upper and lower interference arms of the unbalanced Mach-Zehnder interferometer, λ is the optical wavelength input to the unbalanced Mach-Zehnder interferometer, which is reflected as a frequency by conversion. E 2 is the amplitude when the optical carrier microwave signal enters the unbalanced Mach-Zehnder interferometer, and P up , P down are the output powers of the two output terminals of the unbalanced Mach-Zehnder interferometer respectively.

[0082] The comparison function relationship between the output power of the instantaneous frequency measurement unit constructed using an unequal-arm Mach-Zehnder interferometer and the input signal frequency. The above relationship of the power ratio proves the power irrelevance, making the measurement result of the system not affected by the input optical power and microwave power.

[0083] The thermally tunable microring resonator mainly consists of a heating electrode, a heating electrode wire, and a heating electrode pad; the heating electrode is arranged above the microring and the unequal-arm Mach-Zehnder interferometer, and both sides of the heating electrode are respectively connected to two heating electrode pads through the heating electrode wires.

[0084] The material of the heating electrode is titanium gold, and the material of the heating electrode wire is copper-aluminum alloy.

[0085] The output spectrum and amplitude comparison function curve of the first instantaneous frequency measurement unit are as Figure 3 shown, and the output spectrum and amplitude comparison function curve of the first instantaneous frequency measurement unit are as Figure 4 shown.

[0086] Step 6: Use a vector network analyzer to generate the microwave signal to be measured, input the microwave signal to be measured into the first and second Mach-Zehnder electro-optical intensity modulators 110 and 210 respectively to obtain the first and second optical carrier microwave signals of the microwave signal to be measured, and then input them into the first and second instantaneous frequency measurement units 200 and 400 respectively, and record the real-time output power of the first and second instantaneous frequency measurement units 200 and 400 through a multi-channel oscilloscope respectively.

[0087] Step 7: Substitute the real-time output power into the respective comparison function relationships of the first and second instantaneous frequency measurement units 200 and 400 for calculation to obtain the measurement frequency of the microwave signal to be measured.

[0088] Since the free spectral ranges of the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit are different, their measurement ranges and precisions are also different. The first instantaneous frequency measurement unit has a larger measurement range, which can cover half of its free spectral range (i.e., 50 GHz), and is suitable for measuring a wide frequency range; while the second instantaneous frequency measurement unit has a smaller spectral period and a relatively narrow measurement range, but under the same system noise conditions, its measurement precision is higher.

[0089] Taking the measurement frequency of the microwave signal to be measured obtained by the first instantaneous frequency measurement unit 200 as the reference measurement frequency, find the one closest to the reference measurement frequency among the measurement frequencies of several microwave signals to be measured obtained by the second instantaneous frequency measurement unit 400 as the final accurate measurement frequency. Thus, by simultaneously collecting the output results of the two frequency measurement units, the requirements of both a wide measurement range and high measurement precision can be met.

[0090] In addition, while measuring the frequency of the radar microwave signal, the angle-of-arrival measurement unit can also synchronously monitor relevant parameters of the radar signal, thereby further enhancing the functionality and application value of the system.

[0091] Step 8: Further additionally add an angle-of-arrival measurement unit to form an angle-of-arrival measuring instrument, and each thermal electrode of the angle-of-arrival measurement unit is connected to a multi-path programmable voltage source.

[0092] The output lights of the first Mach-Zehnder intensity modulator 110 and the second Mach-Zehnder modulator 120 are combined together through the Y-branch 104, and an external thermo-optic tuning unit 101 is added to form a dual-parallel Mach-Zehnder intensity modulator 100.

[0093] The radar signals received by two radar antennas within a range of one optical wavelength are respectively connected to the first and second Mach-Zehnder optoelectronic intensity modulators to respectively form the first and second optical-carrier microwave signals with radar signals of the microwave signal to be measured. After the first optical-carrier microwave signal and the second optical-carrier microwave signal are respectively divided into two optical signals with equal amplitudes through the first Y-branch 102 and the second Y-branch 103, one path is taken from each and combined to form a dual-parallel Mach-Zehnder intensity modulator, and then it is sent to the angle-of-arrival measurement unit 300.

[0094] Thus, the output of the dual-parallel Mach-Zehnder modulator is connected to the angle-of-arrival measurement unit. The input microwave signal can be expressed as: V up (t) = V cos(ω RF t) V down (t) = V cos(ω RF t + β) Step 9: Use the angle-of-arrival measurement module to detect the input optical-carrier microwave signal.

[0095] The angle-of-arrival measurement unit 300 receives the optical-carrier microwave signal output by the Mach-Zehnder optoelectronic intensity modulator, divides it into two parts of the upper and lower sidebands, and outputs them respectively. After passing through the photodetectors, they are input into a multi-channel oscilloscope.

[0096] Specifically, first, the multi-path programmable voltage source in Figure 2 is used to control the thermal electrode 304 on the thermo-tuned micro-ring 301 to adjust the center wavelength of the micro-ring to align with the optical carrier wavelength, and further filter it to reduce the influence on subsequent measurements. Then, by controlling the thermal electrodes 313 and 314 on the Mach-Zehnder interferometer 310 assisted by the tuned micro-ring, wavelength separation of the upper and lower sidebands of the optical-carrier microwave signal is achieved. The upper and lower sideband signals are respectively guided to the photodetectors 302 and 303 for detection, and the detection results are input into the oscilloscope for recording.

[0097] At this time, the upper and lower sidebands of the optical carrier microwave signal can be expressed as: P +1 = 2E0 2 J +1 2 (m)[1 + cos(β - α)] P -1 = 2E0 2 J -1 2 (m)[1 + cos(β + α)] Among them, P +1 is the sum of the output powers of the upper sideband, and P -1 is the output power of the lower sideband, E0 is the amplitude of the input optical carrier, β is the phase difference caused by the distance difference between the two radar antennas, α is the phase difference of the optical carrier microwave signal, and J n (m) represents the nth-order Bessel function and satisfies J -n (m)=(-1) n J n (m), m represents the independent variable of the Bessel function, usually corresponding to the spatial or frequency parameter in the physical problem; Step 10: By controlling the thermal electrode 101 in the dual-parallel Mach-Zehnder electro-optic modulator to change the parameter α, and then by observing the amplitude change of the oscilloscope, the phase information of the radar microwave signal can be obtained, and then the arrival angle of the unknown radar microwave signal can be inferred from the parameters of the receiving radar antenna.

[0098] According to the relational expressions of the output powers and phase differences of the upper and lower sidebands, the phase difference of the optical carrier microwave signal is inversely calculated, and then the arrival angle is obtained through conversion calculation processing based on the phase difference, the speed of light, and the distance between the antennas.

[0099] Figure 5 from (a) to Figure 5 (d) respectively simulate the output signal power changes of the two output channels of the arrival angle measurement unit when the phase differences of the microwave signals received by the radar antennas are -π / 12, π / 12, -π / 3, and π / 3.

[0100] In summary, the present invention realizes the synchronous measurement of the frequency information and direction information of the radar microwave signal through the cooperation of the dual-parallel Mach-Zehnder electro-optic modulator, the frequency measurement unit, and the arrival angle measurement unit. This scheme has the remarkable characteristics of simple structure, high measurement accuracy, wide measurement range, and excellent stability. In practical engineering applications, the design parameters of the measurement unit can be flexibly adjusted according to specific requirements, so as to further improve the measurement accuracy and meet the requirements of diverse application scenarios.

[0101] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A silicon-based integrated device for synchronous measurement of microwave frequency and angle of arrival, characterized in that: It includes two radar antennas arranged at intervals, connected to the electrical modulation terminals of a dual-parallel Mach-Zehnder electro-optic intensity modulator, for receiving an external microwave signal to be measured and sending it to the dual-parallel Mach-Zehnder electro-optic intensity modulator (100); It includes a dual-parallel Mach-Zehnder electro-optic intensity modulator (100), for receiving an optical carrier input from an external light source (5) and loading the microwave signal to be measured of the radar antenna onto the optical carrier, and then generating two optical carrier microwave signals and sending them to a measurement unit for synchronous measurement of microwave frequency and angle of arrival; It includes a first instantaneous frequency measurement unit (200), an angle of arrival measurement unit (300) and a second instantaneous frequency measurement unit (400), connected to the output terminals of the dual-parallel Mach-Zehnder electro-optic intensity modulator (100), respectively used for rough measurement of the frequency of the optical carrier microwave signal, measurement of the angle of arrival, and fine measurement of the frequency.

2. The silicon-based integrated device for synchronous measurement of microwave frequency and angle of arrival according to claim 1, characterized in that: The dual-parallel Mach-Zehnder electro-optic intensity modulator (100) is mainly composed of two Mach-Zehnder electro-optic intensity modulators. Each Mach-Zehnder electro-optic intensity modulator is provided with two output terminals. The four output terminals of the two Mach-Zehnder electro-optic intensity modulators are combined into one output terminal and connected to the angle of arrival measurement unit (300), and the other two output terminals are respectively connected to the first instantaneous frequency measurement unit (200) and the second instantaneous frequency measurement unit (400).

3. A silicon-based integrated device for synchronous measurement of microwave frequency and angle of arrival, according to claim 1 or 2, characterized in that: The dual-parallel Mach-Zehnder electro-optic intensity modulator (100) includes a first Mach-Zehnder electro-optic intensity modulator (110), a second Mach-Zehnder electro-optic intensity modulator (120), a thermal electrode (101), a first Y-branch (102) and a second Y-branch (103); The input terminals of the first Mach-Zehnder electro-optic intensity modulator (110) and the second Mach-Zehnder electro-optic intensity modulator (120) are used to connect to the light source (5) after passing through an input Y-branch. The output terminals of the first Mach-Zehnder electro-optic intensity modulator (110) and the second Mach-Zehnder electro-optic intensity modulator (120) are each divided into two output terminals through the first Y-branch (102) and the second Y-branch (103). One branch terminal of each of the first Y-branch (102) and the second Y-branch (103) is respectively connected to the first instantaneous frequency measurement unit (200) and the second instantaneous frequency measurement unit (400). The other branch terminals of the first Y-branch (102) and the second Y-branch (103) are combined into one path / one end and connected to the angle of arrival measurement unit (300); The input Y-branch at the output end of the Mach-Zehnder electro-optic intensity modulator divides each output optical carrier microwave signal into two paths with uniform intensity. The two Mach-Zehnder electro-optic intensity modulators altogether output four optical carrier microwave signals. Two of the optical carrier microwave signals are respectively input to the first and second frequency measurement units (200, 400), and the other two are combined at the combined branch end and then input to the arrival angle measurement unit (300); near the collective end of one of the first Y-branch (102) and the second Y-branch (103), a thermal electrode (101) is provided, and a voltage is applied to the thermal electrode (101) to heat-modulate the phase of the optical carrier microwave signal passing through the Y-branch.

4. The silicon-based integrated device for synchronous measurement of microwave frequency and angle of arrival according to claim 3, wherein: Each of the radar antennas receives the microwave signals to be measured of an external object to be measured from the three-dimensional space. The two radar antennas are electrically connected to the traveling-wave electrodes of the two Mach-Zehnder electro-optic intensity modulators, and the two received microwave signals to be measured with a phase difference are respectively loaded and modulated onto the optical carriers.

5. The silicon-based integrated device for synchronous measurement of microwave frequency and angle of arrival according to claim 1, characterized in that: Each of the measurement units includes a thermally tunable microring resonator, an unequal-arm Mach-Zehnder interferometer, and two detection modules; the input end of the unequal-arm Mach-Zehnder interferometer is connected to an output end of a dual-parallel Mach-Zehnder electro-optic intensity modulator through a waveguide. A thermally tunable microring resonator is provided beside the waveguide at the input end of the unequal-arm Mach-Zehnder interferometer. The two output ends of the unequal-arm Mach-Zehnder interferometer are respectively connected to the two detection modules, and a delay line, a thermal electrode or a microring is provided on the interference arms inside the unequal-arm Mach-Zehnder interferometer.

6. The silicon-based integrated device for synchronous measurement of microwave frequency and angle of arrival according to claim 5, wherein: The first instantaneous frequency measurement unit (200) includes a first thermally tunable microring resonator (201), a first unequal-arm Mach-Zehnder interferometer (210), a first detection module (202) and a second detection module (203); the input end of the first unequal-arm Mach-Zehnder interferometer (210) is connected to the first output end of a dual-parallel Mach-Zehnder electro-optic intensity modulator (100) through a waveguide. A first thermally tunable microring resonator (201) is provided beside the waveguide at the input end of the first unequal-arm Mach-Zehnder interferometer (210). The two output ends of the first unequal-arm Mach-Zehnder interferometer (210) are respectively connected to the first detection module (202) and the second detection module (203), and a delay line (211) and a thermal electrode (212) are respectively provided on the two interference arms inside the first unequal-arm Mach-Zehnder interferometer (210); The second instantaneous frequency measurement unit (400) includes a third thermally tunable microring resonator (401), a second unbalanced Mach-Zehnder interferometer (410), a fifth detection module (402) and a sixth detection module (403); the input end of the second unbalanced Mach-Zehnder interferometer (410) is connected to the second output end of the dual-parallel Mach-Zehnder electro-optic intensity modulator (100) through a waveguide, a third thermally tunable microring resonator (401) is arranged beside the waveguide at the input end of the second unbalanced Mach-Zehnder interferometer (410), the two output ends of the second unbalanced Mach-Zehnder interferometer (410) are respectively connected to the fifth detection module (402) and the sixth detection module (403), and a delay line (411) and a thermal electrode (412) are respectively arranged on the two interference arms inside the first unbalanced Mach-Zehnder interferometer (210); The arrival angle measurement unit (300) includes a second thermally tunable microring resonator (301), a microring-assisted unbalanced Mach-Zehnder interferometer (310), a third detection module (302) and a fourth detection module (303); the input end of the microring-assisted unbalanced Mach-Zehnder interferometer (310) is connected to the third output end of the dual-parallel Mach-Zehnder electro-optic intensity modulator (100) through a waveguide, a second thermally tunable microring resonator (301) is arranged beside the waveguide at the input end of the microring-assisted unbalanced Mach-Zehnder interferometer (310), the two output ends of the microring-assisted unbalanced Mach-Zehnder interferometer (310) are respectively connected to the third detection module (302) and the fourth detection module (303), a delay line (311) and a microring (312) are respectively arranged on the two interference arms inside the microring-assisted unbalanced Mach-Zehnder interferometer (310), a thermal electrode (314) is arranged on the side of the input waveguide beside the delay line (311), and a thermal electrode (313) is arranged beside the microring (312); The lengths of the delay lines (411) of the second instantaneous frequency measurement unit (400) are all greater than those of the delay line (211) of the first instantaneous frequency measurement unit (200) and the delay line (311) of the arrival angle measurement unit (300); the sizes of the thermally tunable microring resonators of the first instantaneous frequency measurement unit (200), the second instantaneous frequency measurement unit (400) and the arrival angle measurement unit (300) are the same, and each thermally tunable microring resonator is provided with a thermal electrode.

7. A method for synchronously measuring microwave frequency and angle of arrival applied to the silicon-based integrated device according to any one of claims 1-6, characterized in that: The method simultaneously measures the microwave frequency and the arrival angle, specifically: Step 1: Connect the silicon-based integrated device to a tunable laser, a radar antenna, a multi-channel oscilloscope and a multi-channel programmable voltage source respectively; Step 2: Turn on the tunable laser to emit a calibration optical carrier at 1550 nm, and divide the optical carrier into two paths with equal intensity through a Y-branch, and send them into the first Mach-Zehnder electro-optic intensity modulator (110) and the second Mach-Zehnder electro-optic intensity modulator (120) respectively to form two optical carrier microwave signals of the calibration optical carrier, and adjust the bias voltage to make the first and second Mach-Zehnder electro-optic intensity modulators work at the minimum bias point to form a carrier-suppressed modulation format; Step 3: After the first optical microwave signal is split into two paths with equal amplitudes by the first Y-branch (102), one path enters the first instantaneous frequency measurement unit; After the second optical microwave signal is split into two paths with equal amplitudes by the second Y-branch (103), one path enters the second instantaneous frequency measurement unit; Step 4: Use a multi-channel voltage source to control the thermally tunable microring resonators (201, 401) in the first and second instantaneous frequency measurement units (200, 400); Step 5: Use a microwave source to sweep the frequency of the optical microwave signal within the working range and record the output powers of the two output signals of the first and second instantaneous frequency measurement units (200, 400) respectively through a multi-channel oscilloscope. Subsequently, compare the output powers of the two output signals of each instantaneous frequency measurement unit at each input microwave signal frequency during the frequency sweep to obtain a power ratio. For each instantaneous frequency measurement unit, fit and establish the relationship between the input microwave signal frequency of different frequency sweeps and the corresponding power ratio to obtain a comparison function relationship, thus completing the calibration work; Step 6: Input the microwave signal to be measured into the first and second Mach-Zehnder electro-optic intensity modulators (110, 210) to obtain the first and second optical microwave signals of the microwave signal to be measured respectively, and then input them into the first and second instantaneous frequency measurement units (200, 400) respectively, and record the real-time output powers of the first and second instantaneous frequency measurement units (200, 400) through a multi-channel oscilloscope; Step 7: Substitute the real-time output powers into the respective comparison function relationships of the first and second instantaneous frequency measurement units (200, 400) for calculation to obtain the measured frequency of the microwave signal to be measured; Step 8: The radar signals received by the two radar antennas are respectively connected to the first and second Mach-Zehnder electro-optic intensity modulators to form the first and second optical microwave signals of the microwave signal to be measured respectively; After the first optical microwave signal and the second optical microwave signal are respectively split into two optical signals with equal amplitudes by the first Y-branch (102) and the second Y-branch (103), one path from each is combined and sent to the angle-of-arrival measurement unit (300); Step 9: The angle-of-arrival measurement unit (300) receives the optical microwave signal output by the Mach-Zehnder electro-optic intensity modulator and splits it into two parts of the upper and lower sidebands, and outputs them respectively. After passing through photodetectors, they are input into a multi-channel oscilloscope; Step 10: Adjust the thermally tunable microring resonator laid at one arm waveguide of the double-parallel Mach-Zehnder electro-optic intensity modulator to change the phase difference between the upper and lower sidebands of the optical microwave signals output by the two arms. The angle of arrival of the radar microwave signal is obtained by recording the waveform on the multi-channel oscilloscope.

8. A method for synchronously measuring microwave frequency and angle of arrival according to claim 7, characterized in that: In the said Step 5, by changing the frequencies of the microwave signals input to the first and second Mach-Zehnder electro-optic intensity modulators (110, 210), establish the relationship between the power ratio of the two output powers of the first and second instantaneous measurement units (200, 400) and the input signal frequency respectively and fit and construct a comparison function relationship. The power ratio is expressed by the formula: ACF = P up / P down = tan 2 (πn g ΔL / λ) P up = sin 2 (πn g ΔL / λ)E 2 P down = cos 2 (πn g ΔL / λ)E 2 where, ACF is the power ratio, n g is the group refractive index of the fundamental mode in the waveguide of the silicon-based optical chip, ΔL is the length difference between the upper and lower interference arms of the unbalanced Mach-Zehnder interferometer, λ is the optical wavelength input to the unbalanced Mach-Zehnder interferometer, E 2 is the amplitude when the optical carrier microwave signal enters the unbalanced Mach-Zehnder interferometer, P up and P down are the output powers of the two output terminals of the unbalanced Mach-Zehnder interferometer respectively.

9. A method for synchronously measuring microwave frequency and angle of arrival according to claim 7, characterized in that: In step 7, after obtaining the measurement frequencies of the microwave signals to be measured obtained by the first and second instantaneous frequency measurement units (200, 400), the measurement frequency of the microwave signals to be measured obtained by the first instantaneous frequency measurement unit (200) is used as a reference measurement frequency, and one of the measurement frequencies of the microwave signals to be measured obtained by the second instantaneous frequency measurement unit (400) that is closest to the reference measurement frequency is found as the final accurate measurement frequency.

10. A method for synchronously measuring microwave frequency and angle of arrival according to claim 7, characterized in that: In step 10, the output power of the arrival angle measurement unit is a function of the phase difference of the light-carrying microwave signals output by two Mach-Zehnder photoelectric modulators of the dual parallel Mach-Zehnder photoelectric intensity modulator, which is expressed as follows: P +1 = 2E0 2 J +1 2 (m)[1 + cos(β - α)] P -1 = 2E0 2 J -1 2 (m)[1 + cos(β + α)] Among them, P +1 is the sum of the output powers of the upper sideband, and P -1 is the output power of the lower sideband. E0 is the amplitude of the input optical carrier, β is the phase difference caused by the distance difference between the two radar antennas, α is the phase difference of the optical carrier microwave signal, and J n (m) represents the nth-order Bessel function and satisfies J -n (m) = (-1) n J n (m), where m represents the independent variable of the Bessel function; According to the above formula, the phase difference of the optical microwave signal is calculated based on the output power of the upper and lower sidebands, which is the phase difference of the microwave signals received by the two antennas. Then, the time delay of the two radar antennas receiving the microwave signals can be inferred based on the phase difference, and then the arrival angle can be obtained by conversion and calculation based on the radar spacing distance.

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