A silicon-based integrated device and measurement method for synchronous measurement of microwave frequency and arrival angle

Abstract

The present invention discloses a silicon-based integrated device and measurement method for synchronous measurement of microwave frequency and arrival angle. A light source is used to emit an optical carrier to the input end of a dual-parallel Mach-Zehnder optoelectronic intensity modulator. Two radar antennas arranged at intervals receive the microwave signal to be measured and send it to the dual-parallel Mach-Zehnder optoelectronic intensity modulator. The dual-parallel Mach-Zehnder optoelectronic intensity modulator loads the microwave signal to be measured onto the optical carrier to generate two optical microwave signals and sends them to a first and second instantaneous frequency measurement unit and an arrival angle measurement unit, respectively, to perform rough and fine frequency measurement and arrival angle measurement of the optical microwave signal. The present invention adopts a single structure to achieve synchronous and efficient measurement of radar microwave signal frequency and arrival angle, significantly improving detection efficiency, solving the technical problems of on-chip integration, high precision, lightweight, low power consumption, and powerful simultaneous measurement of microwave frequency and arrival angle, and enhancing the practicality and applicability of the system.

Description

Technical Field

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

[0002] With the rapid development of radar and communication technologies, the microwave frequency bands used in modern electronic information devices are becoming increasingly wider and more dynamic. Future technological developments will place higher standards on microwave signal measurement. On the one hand, measurement tasks have expanded from the traditional two basic parameters of frequency and amplitude to include multi-dimensional parameters such as frequency, amplitude, phase, signal type, angle of arrival, and time of arrival. On the other hand, the operating frequency range continues to increase, covering almost all frequencies from 2 MHz to 300 GHz. However, traditional electronic frequency measurement solutions typically only cover up to 18 GHz, which is no longer able to meet these new requirements. These technical bottlenecks urgently require new solutions.

[0003] Microwave photonics technology combines the advantages of microwaves and photonics. By utilizing photonics to generate, transmit, and process microwave signals, it exhibits remarkable characteristics such as wide instantaneous bandwidth, light weight, low loss, and strong resistance to electromagnetic interference. This technology has been widely applied in fields such as radar, satellite communications, and information technology, and it also provides a new solution for measuring the frequency and angle of arrival of microwave signals. In recent years, research on microwave signal frequency and angle of arrival measurement based on microwave photonics has made significant progress, and related results have been widely reported. Existing microwave frequency measurement methods mainly include frequency-amplitude mapping, frequency-space mapping, and frequency-time domain mapping. These methods convert the frequency information of the microwave signal into power or time information, thereby indirectly inferring the frequency parameters. Frequency-amplitude mapping has attracted much attention due to its simple design and high accuracy. However, existing solutions generally rely on a single optical filter, which makes it difficult to achieve both wide measurement bandwidth and high measurement accuracy. Furthermore, no device currently exists that can simultaneously measure frequency and angle of arrival.

[0004] Therefore, the existing technology lacks an on-chip, lightweight, low-power, and powerful microwave frequency and arrival angle measurement solution. Summary of the Invention

[0005] In response to the problems existing in the background technology, the purpose of the present invention is to provide a device and method for realizing microwave frequency and arrival angle measurement using a dual parallel Mach-Zehnder modulator. Its core goal is to solve the technical difficulties of synchronously measuring the frequency and arrival angle of radar microwave signals under high-precision and large-bandwidth conditions, and to solve the technical problems of simultaneous measurement of microwave frequency and arrival angle in an on-chip integrated, lightweight, low-power and powerful manner.

[0006] The technical solution adopted in the present invention is:

[0007] 1. A silicon-based integrated device for synchronous measurement of microwave frequency and arrival angle:

[0008] The invention comprises two radar antennas arranged at intervals, connected to the electrical modulation end of the dual-parallel Mach-Zehnder optoelectronic intensity modulator, and used for receiving an external microwave signal to be measured and sending the signal to the dual-parallel Mach-Zehnder optoelectronic intensity modulator;

[0009] It includes a dual-parallel Mach-Zehnder optoelectronic intensity modulator, which is used to receive an optical carrier input from an external light source and load the microwave signal to be measured from the radar antenna onto the optical carrier, thereby generating two optical-carrying microwave signals and sending them to a measurement unit for synchronous measurement of microwave frequency and arrival angle;

[0010] It includes a first instantaneous frequency measurement unit, an arrival angle measurement unit and a second instantaneous frequency measurement unit, which are connected to the output end of the dual parallel Mach-Zehnder photoelectric intensity modulator and are used for performing rough frequency measurement, arrival angle measurement and fine frequency measurement of the light-carrying microwave signal respectively.

[0011] The device structure of the present invention is based on an optical waveguide structure. The first instantaneous frequency measurement unit, the arrival angle measurement unit and the second instantaneous frequency measurement unit are all similar waveguide structures, but they are different.

[0012] The dual-parallel Mach-Zehnder photoelectric intensity modulator is mainly composed of two Mach-Zehnder photoelectric intensity modulators, each of which is provided with two output ends. The four output ends of the two Mach-Zehnder photoelectric intensity modulators are combined into one output end and connected to the angle of arrival measurement unit, and the remaining two output ends are connected to the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit respectively.

[0013] In the dual-parallel Mach-Zehnder optoelectronic intensity modulator, a Y branch is provided at the output end of each Mach-Zehnder optoelectronic intensity modulator to split each optical microwave signal outputted by the modulator into two channels with uniform intensity. The two Mach-Zehnder optoelectronic intensity modulators form a total of four optical microwave signals, two of which are input to the first and second frequency measurement units respectively, and the other two channels are combined and input to the arrival angle measurement unit.

[0014] Two Mach-Zehnder optoelectronic intensity modulators process optically carried microwave signals of different phases respectively.

[0015] The dual parallel Mach-Zehnder photoelectric intensity modulator includes a first Mach-Zehnder photoelectric intensity modulator, a second Mach-Zehnder photoelectric intensity modulator, a hot electrode, a first Y branch and a second Y branch; the input ends of the first Mach-Zehnder photoelectric intensity modulator and the second Mach-Zehnder photoelectric intensity modulator are used to connect to the light source after passing through an input Y branch, and the output ends of the first Mach-Zehnder photoelectric intensity modulator and the second Mach-Zehnder photoelectric intensity modulator are respectively divided into two output ends through the first Y branch and the second Y branch, and one of the branch ends of each of the first Y branch and the second Y branch is connected to the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit respectively, and the first Y branch The other branch ends of the branch and the second Y branch are merged into one path / one end and connected to the angle of arrival measurement unit; the input Y branch of the output end of the Mach-Zehnder photoelectric intensity modulator divides each output optical microwave signal into two paths with uniform intensity. The two Mach-Zehnder photoelectric intensity modulators output a total of four optical microwave signals, two of which are input to the first and second frequency measurement units respectively, and the other two are combined through the merged branch end and input to the angle of arrival measurement unit; a hot electrode is provided near the collective end of one of the first Y branch and the second Y branch, and a voltage is applied to the hot electrode to heat and modulate the phase of the optical microwave signal passing through the Y branch.

[0016] Each of the radar antennas receives a microwave signal to be measured from an external object to be measured in three-dimensional space. The two radar antennas are electrically connected to traveling wave electrodes of two Mach-Zehnder photoelectric intensity modulators, and the two received microwave signals to be measured with a phase difference are respectively loaded into the modulated optical carrier.

[0017] The measurement units each include a thermally tuned 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 photoelectric intensity modulator via a waveguide; a thermally tuned microring resonator is arranged on the side of 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 thermode, or a microring is arranged on the interference arm inside the unequal-arm Mach-Zehnder interferometer.

[0018] The first instantaneous frequency measurement unit includes a first thermally tuned 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 dual-parallel Mach-Zehnder photoelectric intensity modulator via a waveguide, the first thermally tuned microring resonator is arranged on the side of the waveguide of 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 the two interference arms inside the first unequal-arm Mach-Zehnder interferometer are respectively provided with a delay line and a thermode;

[0019] The second instantaneous frequency measurement unit includes a third thermally tuned microring resonator, a second unequal-arm Mach-Zehnder interferometer, a fifth detection module, and a sixth detection module; the input end of the second unequal-arm Mach-Zehnder interferometer is connected to the second output end of the dual-parallel Mach-Zehnder photoelectric intensity modulator via a waveguide, a third thermally tuned microring resonator is provided on the side of the waveguide of the input end of the second unequal-arm Mach-Zehnder interferometer, two output ends of the second unequal-arm Mach-Zehnder interferometer are respectively connected to the fifth detection module and the sixth detection module, and a delay line and a hot electrode are respectively provided on the two interference arms inside the first unequal-arm Mach-Zehnder interferometer;

[0020] The arrival angle measurement unit includes a second thermally tuned microring resonator, a microring-assisted unequal-arm Mach-Zehnder interferometer, a third detection module, and a fourth detection module; the input end of the microring-assisted unequal-arm Mach-Zehnder interferometer is connected to the third output end of the dual-parallel Mach-Zehnder photoelectric intensity modulator via a waveguide, a second thermally tuned microring resonator is provided on the side of the waveguide at the input end of the microring-assisted unequal-arm Mach-Zehnder interferometer, two output ends of the microring-assisted unequal-arm Mach-Zehnder interferometer are connected to the third detection module and the fourth detection module respectively, a delay line and a microring are provided on the two interference arms inside the microring-assisted unequal-arm Mach-Zehnder interferometer respectively, a hot electrode is provided on the input waveguide side next to the delay line, and a hot electrode is provided on the side of the microring;

[0021] The length of the delay line of the second instantaneous frequency measurement unit is greater than the delay line of the first instantaneous frequency measurement unit and the delay line of the arrival angle measurement unit; the thermally tuned microring resonators of the first instantaneous frequency measurement unit, the second instantaneous frequency measurement unit, and the arrival angle measurement unit are the same size, and each thermally tuned microring resonator is provided with a hot electrode.

[0022] The arrival angle described in the present invention is a plane angle, and may also be a solid angle.

[0023] 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 vertically coupled gratings.

[0024] 2. A method for synchronously measuring microwave frequency and arrival angle, wherein the method simultaneously measures microwave frequency and arrival angle, specifically:

[0025] 2. A high-precision, wide-bandwidth microwave frequency measurement method:

[0026] To achieve high-precision, wide-bandwidth microwave frequency measurement, the present invention provides a silicon-based integrated microwave frequency measuring instrument. The instrument comprises a microwave source, a multi-channel controlled voltage source, a multi-channel oscilloscope, and a 1550 nm tunable laser. The tunable laser serves as the light source and is located at the input of the silicon-based integrated device. The multi-channel controlled voltage source and the multi-channel oscilloscope are both connected to the silicon-based integrated device. The multi-channel oscilloscope utilizes a multi-channel low-speed oscilloscope.

[0027] At this time, the silicon-based integrated device for frequency measurement only includes the first Mach-Zehnder photoelectric intensity modulator, the second Mach-Zehnder photoelectric intensity modulator, the input Y branch, the first instantaneous frequency measurement unit, and the second instantaneous frequency measurement unit. The microwave source is connected to the traveling wave electrodes of the first Mach-Zehnder photoelectric intensity modulator and the second Mach-Zehnder photoelectric intensity modulator. The multi-path controlled voltage source is connected to the hot electrodes of the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit and the hot electrodes of the Mach-Zehnder photoelectric intensity modulator. The multi-channel oscilloscope is connected to the detectors of the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit in the silicon-based integrated device.

[0028] 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 .

[0029] Step 1: The silicon-based integrated device is used as an optical chip and is connected to a tunable laser, a radar antenna, a multi-channel oscilloscope, and a multi-path controlled voltage source respectively; a 1550 nm tunable laser is used as a light source.

[0030] Step 2: Turn on the tunable laser to emit a 1550 nm calibration optical carrier and split the optical carrier into two equal-intensity paths through a Y-branch. The two paths are sent to the first and second Mach-Zehnder intensity modulators, forming two optical microwave signals of the calibration optical carrier. The bias voltage is adjusted so that the first and second Mach-Zehnder intensity modulators operate at the minimum bias point, forming a carrier suppression modulation format.

[0031] Step 3: The first optical microwave signal is split into two paths with equal amplitudes through the first Y branch, and one path enters the first instantaneous frequency measurement unit;

[0032] The second optical microwave signal is split into two paths with equal amplitudes by the second Y branch, and one path enters the second instantaneous frequency measurement unit;

[0033] Step 4: Use a multi-channel voltage source to control the thermally tuned microring resonators in the first and second instantaneous frequency measurement units, specifically the thermally tuned microring resonators laid on the microring and the unequal-arm Mach-Zehnder interferometer waveguide, so that they operate in the required working state, that is, their operating center wavelength is consistent with the wavelength of the optical carrier;

[0034] Step 5: Use a microwave source to sweep the frequency of the optical microwave signal within the working range of the frequency measuring instrument and record the output power of the two output signals of the first and second instantaneous frequency measurement units respectively through a multi-channel oscilloscope. Then, divide and compare the output power of the two output signals of each instantaneous frequency measurement unit at each swept input microwave signal frequency to obtain a power ratio. For each instantaneous frequency measurement unit, fit and establish the relationship between the input microwave signal frequency of different swept frequencies and the corresponding power ratio to obtain a comparison function relationship, and complete 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.

[0035] Step 6: Inputting the microwave signal to be measured into the first and second Mach-Zehnder photoelectric intensity modulators to obtain the first and second light-carrying microwave signals of the microwave signal to be measured, respectively, and then inputting them into the first and second instantaneous frequency measurement units, respectively, and recording the real-time output power of the first and second instantaneous frequency measurement units using a multi-channel oscilloscope;

[0036] Step 7: Substituting the real-time output power into the comparison function relationship of the first and second instantaneous frequency measurement units respectively to calculate and obtain the measurement frequency of the microwave signal to be measured;

[0037] In step 5, a bias voltage is applied by a voltage source to change the frequency of the microwave signals input to the first and second Mach-Zehnder intensity modulators, thereby establishing a relationship between the power ratio between the two output powers of the first and second instantaneous measurement units and the input signal frequency and fitting a comparison function relationship. The power ratio is expressed by the formula:

[0038] ACF = P up / P down = tan 2 (πn g ΔL / λ)

[0039] P up = sin 2 (πn g ΔL / λ)E 2

[0040] P down = cos 2 (πn g ΔL / λ)E 2

[0041] Where ACF is the power ratio, n g is the group refractive index of the fundamental mode in the silicon-based optical chip waveguide, ΔL is the length difference between the upper and lower interference arms of the unequal-arm Mach-Zehnder interferometer, and λ is the wavelength of light input to the unequal-arm Mach-Zehnder interferometer, which is converted by λ as the frequency.2 is the amplitude of the optical microwave signal when it enters the unequal-arm Mach-Zehnder interferometer, P up 、P down are the output powers at the two output ends of the unequal-arm Mach-Zehnder interferometer.

[0042] In a specific implementation, applying the bias voltage and inputting the microwave signal are not the same device. The microwave source is used to generate the input microwave signal, and the voltage source is used to apply the bias voltage.

[0043] 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, since the first instantaneous frequency measurement unit performs a rough measurement and its result is only a rough estimate, and the second instantaneous frequency measurement unit performs a precise measurement and its result is several precise results, the measurement frequency of the microwave signals to be measured obtained by the first instantaneous frequency measurement unit is used as the reference measurement frequency, and among the measurement frequencies of the microwave signals to be measured obtained by the second instantaneous frequency measurement unit, the one closest to the reference measurement frequency is found as the final precise measurement frequency.

[0044] 3. A high-precision radar microwave signal arrival angle measurement method:

[0045] In order to achieve large-scale, high-precision radar signal arrival angle measurement, an arrival angle measurement unit is further added to form an arrival angle measuring instrument. Each hot electrode of the arrival angle measurement unit is connected to a multi-path controlled voltage source.

[0046] Step 8: The radar signals received by two radar antennas within a microwave signal wavelength range are respectively connected to the first and second Mach-Zehnder photoelectric intensity modulators to form the first and second optically-carried microwave signals of the microwave signal to be measured;

[0047] The radar antenna uses a microwave signal wavelength of millimeters or centimeters, so that the distance between the two radar antennas can reach the optical wavelength range, which can reach the mm level.

[0048] Based on step 3, the first optical microwave signal and the second optical microwave signal are respectively split into two optical signals with equal amplitudes through the first Y branch and the second Y branch, and one of the optical signals is combined to form a dual parallel Mach-Zehnder intensity modulator, which is then sent to the arrival angle measurement unit;

[0049] Step 9: The arrival angle measurement unit receives the optical microwave signal output by the Mach-Zehnder photoelectric intensity modulator and divides it into two parts, the upper sideband and the lower sideband, and outputs them respectively. After passing through the photodetector, they are input into the multi-channel oscilloscope;

[0050] In the arrival angle measurement unit, a micro-ring assisted unequal-arm Mach-Zehnder interferometer is used to split the optical microwave signal output by the Mach-Zehnder photoelectric intensity modulator into two parts according to the wavelength with the optical carrier as the center, respectively serving as the upper and lower sidebands.

[0051] Step 10: Adjust the thermally tuned microring resonator laid on one arm waveguide of the dual parallel Mach-Zehnder optoelectronic intensity modulator to change the phase difference between the upper and lower sidebands of the optical microwave signal output by the two arms, and obtain the arrival angle of the radar microwave signal by recording the waveform on a multi-channel oscilloscope.

[0052] In step 5, a bias voltage is applied by a microwave source to change the frequency of the microwave signals input to the first and second Mach-Zehnder intensity modulators, so as to establish a relationship between the power ratio between the two output powers of the first and second instantaneous measurement units and the input signal frequency and fit a comparison function relationship. The power ratio is expressed by the formula:

[0053] ACF = P up / P down = tan 2 (πn g ΔL / λ)

[0054] P up = sin 2 (πn g ΔL / λ)E 2

[0055] P down = cos 2 (πn g ΔL / λ)E 2

[0056] Where ACF is the power ratio, n g is the group refractive index of the fundamental mode in the silicon-based optical chip waveguide, ΔL is the length difference between the upper and lower interference arms of the unequal-arm Mach-Zehnder interferometer, and λ is the wavelength of light input to the unequal-arm Mach-Zehnder interferometer, which is converted by λ as the frequency. 2 is the amplitude of the optical microwave signal when it enters the unequal-arm Mach-Zehnder interferometer, P up 、P down are the output powers at the two output ends of the unequal-arm Mach-Zehnder interferometer.

[0057] 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, since the first instantaneous frequency measurement unit performs a rough measurement and its result is only a rough estimate, and the second instantaneous frequency measurement unit performs a precise measurement and its result is several precise results, the measurement frequency of the microwave signals to be measured obtained by the first instantaneous frequency measurement unit is used as the reference measurement frequency, and among the measurement frequencies of the microwave signals to be measured obtained by the second instantaneous frequency measurement unit, the one closest to the reference measurement frequency is found as the final precise measurement frequency.

[0058] 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 the two Mach-Zehnder photoelectric modulators of the dual parallel Mach-Zehnder photoelectric intensity modulator, which is expressed as follows:

[0059] P +1 = 2E0 2 J +1 2 (m)[1 + cos(β - α)]

[0060] P -1 = 2E0 2 J -1 2 (m)[1 + cos(β + α)]

[0061] Among them, P +1 is the output power sum of the upper sideband, P -1 is the output power of the lower sideband, E0 is the input optical carrier amplitude, β is the phase difference caused by the distance difference between the two radar antennas, α is the phase difference of the optical 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, which usually corresponds to the space or frequency parameter in physical problems;

[0062] 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 is inferred based on the phase difference, and the arrival angle is obtained by conversion and calculation based on the radar separation distance.

[0063] The dual-parallel Mach-Zehnder photoelectric intensity modulator described in the present invention is used to load a microwave signal to be measured with a specific arrival angle onto an optical carrier to generate two optically-carried microwave signals. Each signal is divided into two paths of uniform intensity by a Y-branch structure, forming a total of four optically-carried microwave signals, two of which are input into two frequency measurement units respectively, and the other two are combined and input into the arrival angle measurement unit. The frequency measurement unit maps the frequency of the optically-carried microwave signal to a power value by providing two independent linear frequency responses, and accurately determines the frequency of the microwave signal through power detection. The arrival angle measurement unit infers the relative phase of the two optically-carried microwave signals by detecting the power value of the output port, and then calculates the arrival angle of the microwave signal.

[0064] The present invention adopts a single structure to achieve synchronous and efficient measurement of radar microwave signal frequency and arrival angle, significantly improves detection efficiency, and enhances the practicality and applicability of the system.

[0065] The present invention has the following beneficial effects:

[0066] The silicon-based microwave frequency measuring instrument proposed in the present invention adopts a two-stage unequal-arm Mach-Zehnder interferometer with different delay amounts. By combining the preliminary measurement with large bandwidth and low precision with the fine measurement with small bandwidth and high precision, the complementary measurement performance is achieved, and a wide microwave frequency measurement range and high measurement accuracy are realized.

[0067] The silicon-based microwave detection solution of the present invention can not only measure the frequency of microwave signals with high precision, but also simultaneously achieve high-precision measurement of the arrival angle of microwave signals, greatly improving the functionality and practicality of the system.

[0068] The present invention realizes hybrid integration of multiple physical fields by integrating modulators, detectors and thermal tuning devices, and has significant characteristics such as high integration, light weight and low loss, providing strong support for building high-performance silicon-based microwave detection systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a structural schematic diagram of the present invention;

[0070] Figure 2 is a diagram of the experimental apparatus of the present invention;

[0071] 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;

[0072] 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;

[0073] Figure 5 FIG. 3 is a schematic diagram of the output spectrum of the arrival angle measurement unit 300 of the present invention. DETAILED DESCRIPTION

[0074] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0075] like Figure 1 As shown, the device structure includes a dual parallel Mach-Zehnder photoelectric intensity modulator, a first instantaneous frequency measurement unit 200 , an arrival angle measurement unit 300 and a second instantaneous frequency measurement unit 400 .

[0076] A light source 5 may be included for emitting an optical carrier to the input end of a dual parallel Mach-Zehnder optoelectronic intensity modulator.

[0077] The invention comprises two radar antennas arranged at intervals and connected to the electrical modulation end of the dual-parallel Mach-Zehnder optoelectronic intensity modulator, and is used for receiving the external microwave signal to be measured with a specific arrival angle and sending it to the dual-parallel Mach-Zehnder optoelectronic intensity modulator 100 .

[0078] It includes a dual-parallel Mach-Zehnder photoelectric intensity modulator 100, which is used to receive an optical carrier input from an external light source 5 and load the microwave signal to be measured from the radar antenna onto the optical carrier to modulate the optical carrier, thereby generating two optically-carried microwave signals and sending them to three measurement units for synchronous measurement of microwave frequency and arrival angle.

[0079] The system comprises a first instantaneous frequency measurement unit 200, an arrival angle measurement unit 300 and a second instantaneous frequency measurement unit 400, which are optically connected to the output end of the dual parallel Mach-Zehnder photoelectric intensity modulator 100 and are used for performing a relatively coarse frequency measurement, an arrival angle measurement and a relatively fine frequency measurement of the light-carrying microwave signal respectively.

[0080] The dual-parallel Mach-Zehnder optical intensity modulator 100 is mainly composed of two Mach-Zehnder optical intensity modulators arranged in parallel. Each Mach-Zehnder optical intensity modulator is provided with two output terminals. The four output terminals of the two Mach-Zehnder optical intensity modulators are combined into one output terminal and connected to the angle of arrival measurement unit 300. The remaining two output terminals are respectively connected to the first instantaneous frequency measurement unit 200 and the second instantaneous frequency measurement unit 400, thereby forming three output terminals as a whole.

[0081] The dual-parallel Mach-Zehnder photoelectric intensity modulator 100 includes a first Mach-Zehnder photoelectric intensity modulator 110, a second Mach-Zehnder photoelectric intensity modulator 120, a hot electrode 101, a first Y branch 102 and a second Y branch 103; the first Mach-Zehnder photoelectric intensity modulator 110 and the second Mach-Zehnder photoelectric intensity modulator 120 are arranged in parallel, and the input ends of the first Mach-Zehnder photoelectric intensity modulator 110 and the second Mach-Zehnder photoelectric intensity modulator 120 are used to connect to the light source 5 after passing through an input Y branch. More specifically, the input ends of the first Mach-Zehnder photoelectric intensity modulator 110 and the second Mach-Zehnder photoelectric intensity modulator 120 are both connected to the two branch ends of the Y branch, and the collective end of the Y branches serves as the input end of the dual-parallel Mach-Zehnder photoelectric intensity modulator 100 for receiving the light source 5.

[0082] The output ends of the first Mach-Zehnder photoelectric intensity modulator 110 and the second Mach-Zehnder photoelectric intensity modulator 120 are respectively divided into two output ends through the first Y branch 102 and the second Y branch 103. More specifically, the input ends of the first Mach-Zehnder photoelectric intensity modulator 110 and the second Mach-Zehnder photoelectric intensity modulator 120 are respectively connected to the collection end of the first Y branch 102 and the second Y branch 103. The two branch ends of each of the first Y branch 102 and the second Y branch 103 are used to connect to the measurement unit.

[0083] One of the branch ends of each of the first Y-branch 102 and the second Y-branch 103 is connected to the first instantaneous frequency measurement unit 200 and the second instantaneous frequency measurement unit 400, respectively. The other branch ends of each 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. A thermode 101 for modulation is provided near the combined end of one of the first Y-branch 102 and the second Y-branch 103. A voltage is applied to the thermode 101 to heat and modulate the phase of the optical microwave signal passing through the Y-branch, thereby performing a phase shifting function.

[0084] The input Y branch at the output end of the Mach-Zehnder photoelectric intensity modulator splits each optical microwave signal output by the Mach-Zehnder photoelectric intensity modulator into two paths with uniform intensity. The two Mach-Zehnder photoelectric intensity modulators output a total of four optical microwave signals, two of which are input to the first and second frequency measurement units 200 and 400 respectively, and the other two are combined through the combined branch end and input to the arrival angle measurement unit 300.

[0085] Each Mach-Zehnder photoelectric intensity modulator has two interferometer arms inside, and a traveling wave electrode is provided on each interferometer arm and between the two interferometer arms.

[0086] The first and second Mach-Zehnder photoelectric intensity modulators are used to load the microwave signals to be measured with a certain phase difference received by the two radar antennas onto the optical carrier to form an optically carried microwave signal and retain the phase difference information of the microwave signal.

[0087] In a specific implementation, a hot electrode 101 is positioned next to the first Y-branch 102, enabling the first Y-branch 102 to have a phase shifting function. A non-hot electrode is positioned next to the second Y-branch 103, disabling the first Y-branch 102 from having a phase shifting function. The hot electrode 101, placed next to one of the Y-branch 103, is used to adjust the output phase of either of the dual parallel MZEMs, thereby adjusting the output sideband power.

[0088] 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 a three-dimensional space, and each receives a microwave signal to be measured from an external object to be measured in the three-dimensional space. The two radar antennas are electrically connected to traveling wave electrodes of two Mach-Zehnder photoelectric 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. The two received microwave signals to be measured with a phase difference are each loaded and modulated into its corresponding optical carrier.

[0089] The frequency measurement unit maps the frequency of the optical microwave signal to a power value by providing two independent linear frequency responses, and accurately determines the frequency of the microwave signal through power detection. It is specifically divided into a first instantaneous frequency measurement unit and a second instantaneous frequency measurement unit: the first instantaneous frequency measurement unit performs a large-scale rough measurement of the frequency of the unknown microwave signal by detecting the output power, and has the characteristics of a large measurement range and good real-time performance; the second instantaneous measurement unit performs a fine measurement of the frequency information of the unknown microwave signal by detecting the output power, and has the characteristics of high precision and good real-time performance.

[0090] The arrival angle measurement unit infers the relative phase of the two optical microwave signals by detecting the power value of the output port, and then calculates the arrival angle of the microwave signal.

[0091] Each measurement unit includes a thermally tuned 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 photoelectric intensity modulator via a waveguide; a thermally tuned microring resonator is arranged on the side of 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 thermode or a microring is arranged on the interference arm inside the unequal-arm Mach-Zehnder interferometer.

[0092] The first instantaneous frequency measurement unit 200 includes a first thermally tuned 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 the dual-parallel Mach-Zehnder optical intensity modulator 100 via 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 optical intensity modulator 110 of the dual-parallel Mach-Zehnder optical intensity modulator 100. The first thermally tuned microring resonator 201 is arranged on the side of 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. The two interference arms inside the first unequal-arm Mach-Zehnder interferometer 210 are respectively provided with a delay line 211 and a hot electrode 212.

[0093] Delay line 211 is used to change the delay between the two arms of Mach-Zehnder interferometer 210, causing the output waveform to vary periodically according to a sinusoidal function. Thermocouple 212 is used to finely control the delay between the two arms of Mach-Zehnder interferometer 210, thereby adjusting the center wavelength of the output waveform. A fixed voltage is applied to the first thermally tuned microring 201 to precisely adjust the microring's center wavelength, filtering out the optical carrier and retaining only the microwave signal after microwave signal modulation, thereby improving frequency measurement accuracy.

[0094] The second instantaneous frequency measurement unit 400 includes a third thermally tuned microring resonator 401, a second unequal-arm Mach-Zehnder interferometer 410, a fifth detection module 402, and a sixth detection module 403. The input end of the second unequal-arm Mach-Zehnder interferometer 410 is connected to the second output end of the dual-parallel Mach-Zehnder optical intensity modulator 100 via a waveguide, that is, it is connected to one branch end of the second Y-branch 103 at the output end of the second Mach-Zehnder optical intensity modulator 120 of the dual-parallel Mach-Zehnder optical intensity modulator 100. The third thermally tuned microring resonator 401 is arranged on the side of the waveguide at the input end of the second unequal-arm Mach-Zehnder interferometer 410. The two output ends of the second unequal-arm Mach-Zehnder interferometer 410 are respectively connected to the fifth detection module 402 and the sixth detection module 403. The two interference arms inside the first unequal-arm Mach-Zehnder interferometer 210 are respectively provided with a delay line 411 and a hot electrode 412.

[0095] Delay line 411 is used to vary the delay between the two arms of Mach-Zehnder interferometer 410, causing the output waveform to vary periodically according to a sinusoidal function. This differs from delay line 211 in that it varies the delay, resulting in a smaller output spectrum period. Thermocouple 412 is used to finely control the delay between the two arms of Mach-Zehnder interferometer 410, adjusting the central wavelength of the output waveform. A fixed voltage is applied to the second thermally tuned microring 401 to filter out the optical carrier and improve frequency measurement accuracy.

[0096] The arrival angle measurement unit 300 includes a second thermally tuned microring resonator 301, a microring-assisted unequal-arm Mach-Zehnder interferometer 310, a third detection module 302, and a fourth detection module 303. The input end of the microring-assisted unequal-arm Mach-Zehnder interferometer 310 is connected to the third output end of the dual-parallel Mach-Zehnder optical intensity modulator 100 via a waveguide. The second thermally tuned microring resonator 301 is arranged on the side of the waveguide at the input end of the microring-assisted unequal-arm Mach-Zehnder interferometer 310. The two output ends of the microring-assisted unequal-arm 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 unequal-arm Mach-Zehnder interferometer 310. A hot electrode 314 is arranged on the input waveguide side next to the delay line 311, and a hot electrode 313 is arranged on the side of the microring 312.

[0097] Delay line 311 is used to change the delay between the two arms of the Mach-Zehnder interferometer 410. Microring 312 is used to form a microring-assisted unequal-arm Mach-Zehnder interferometer 310, adjusting the output spectrum. Thermopole 314 is used to finely control the delay between the two arms of the Mach-Zehnder interferometer 410, thereby adjusting the center wavelength of the output waveform. Thermopole 313 is used to adjust the microring optical path length, control the microring output center wavelength, change the delay between the two arms of the output light, and thereby change the output spectrum of the microring-assisted unequal-arm Mach-Zehnder interferometer. A fixed voltage is applied to the second thermally tuned microring 301 to filter out the optical carrier and improve the measurement frequency accuracy.

[0098] The micro-ring assisted unequal-arm Mach-Zehnder interferometer 310 is used for wavelength division multiplexing. It uses a 1×2 structure so that the two outputs respectively output the upper and lower order sidebands of the dual parallel Mach-Zehnder optoelectronic modulator.

[0099] Microring 312 uses a narrowband, wide free spectral range, band-stop filter with a Q value of 10 6 The free spectral range is 1 nm. The central wavelength and extinction ratio can be adjusted by the thermoelectrode on the microring.

[0100] The first unequal-arm Mach-Zehnder interferometer is a 2×2 asymmetric Mach-Zehnder interferometer structure with a free spectral range (FSR) of 100 GHz, which can realize a large-scale low-precision mapping relationship between microwave frequency and output power.

[0101] The second unequal-arm Mach-Zehnder interferometer is a 2×2 asymmetric Mach-Zehnder interferometer structure with a free spectral range of 20 GHz, which can achieve high-precision mapping between microwave frequency and output power in a small range.

[0102] When the second instantaneous frequency measurement unit is used in a complementary manner with the first instantaneous frequency measurement module, the system can have a relatively high measurement accuracy while maintaining a large measurement range.

[0103] The two Mach-Zehnder optoelectronic intensity modulators are both in the minimum bias point working state, generating carrier-suppressed double-sideband optical microwave signals.

[0104] The length of the delay line 411 of the second instantaneous frequency measurement unit 400 is greater than 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 similar.

[0105] The thermally tuned 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 of the same size, and each thermally tuned microring resonator is provided with a thermode; that is, the first thermally tuned microring resonator 201 of the first instantaneous frequency measurement unit 200, the third thermally tuned microring resonator 401 of the second instantaneous frequency measurement unit 400, and the second thermally tuned microring resonator 301 of the arrival angle measurement unit 300 are of the same size, and are respectively provided with a thermode 204, a thermode 404, and a thermode 304.

[0106] 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 vertically coupled gratings.

[0107] In the embodiment of the present invention, the specific scheme principle and example of measuring the microwave frequency and arrival angle of radar signals include the following steps:

[0108] First, a silicon-based integrated microwave frequency measurement instrument was designed, consisting of a microwave source, a multi-channel controlled voltage source, a multi-channel oscilloscope, and a 1550 nm tunable laser. The tunable laser, serving as light source 5, was placed at the input of the silicon-based integrated device. Both the multi-channel controlled voltage source and the multi-channel oscilloscope were connected to the silicon-based integrated device. The multi-channel oscilloscope employed a multi-channel low-speed oscilloscope.

[0109] At this time, the silicon-based integrated device for frequency measurement only includes the first Mach-Zehnder photoelectric intensity modulator, the second Mach-Zehnder photoelectric intensity modulator, the input Y branch, the first instantaneous frequency measurement unit, and the second instantaneous frequency measurement unit. The microwave source is connected to the traveling wave electrodes of the first Mach-Zehnder photoelectric intensity modulator and the second Mach-Zehnder photoelectric intensity modulator. The multi-path controlled voltage source is connected to the hot electrodes of the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit and the hot electrode 101 of the Mach-Zehnder photoelectric intensity modulator. The multi-channel oscilloscope is connected to the detectors of the first instantaneous frequency measurement unit and the second instantaneous frequency measurement unit in the silicon-based integrated device.

[0110] 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 .

[0111] Step 1: If Figure 2 As shown in the figure, the silicon-based integrated optical chip is connected to a 1550nm tunable laser, a vector network analyzer, a multi-channel oscilloscope and a multi-path controlled voltage source. Among them, the 1550nm tunable laser outputs an optical carrier, and the angular frequency of the light wave is recorded as ω c , the amplitude is recorded as E0, the initial phase is φ, and the continuous light wave is input to the dual parallel Mach-Zehnder modulator. Among them, the optical carrier can be expressed as:

[0112] E in (t) = E0exp[j(ω c (t) + φ)]

[0113] Among them, E in (t) represents the optical carrier amplitude, exp[] represents the exponential function with the natural constant e (approximately 2.71828) as the base, j represents the imaginary unit, and t represents time (s).

[0114] 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 equal amplitude paths. One path is directly input into the first Mach-Zehnder optoelectronic 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 input into the second Mach-Zehnder intensity modulator. In addition, both Mach-Zehnder intensity modulators are controlled by a voltage source to operate at the minimum bias point. Among them, the input microwave signal amplitude at time t is V0, and the frequency is ω. RF The microwave signal at time t can be expressed as:

[0115] V RF (t) = V0cos(ω RF (t) + θ)

[0116] Here, θ represents the phase difference between the two arms of the MZED caused by the DC bias voltage.

[0117] Step 3: The first and second optically-carried microwave signals are connected to the first and second instantaneous frequency measurement units after passing through respective Y branches.

[0118] Specifically, the first optical microwave signal is split into two paths with equal amplitudes through the first Y branch 102, and one path enters the first instantaneous frequency measurement unit; the second optical microwave signal is split into two paths with equal amplitudes through the second Y branch 103, and one path enters the second instantaneous frequency measurement unit.

[0119] Step 4: Adjust its central wavelength to optimize measurement performance.

[0120] Specifically, by applying different voltages to the thermode 204 of the first thermally tuned microring 201 and the thermode 404 of the third thermally tuned microring 401, the resonant wavelength of the microrings is aligned with the wavelength of the optical carrier, thereby further filtering out the optical carrier and reducing its interference with subsequent measurements. By applying voltages to the thermode 212 in the first unequal-arm Mach-Zehnder interferometer 210 and the thermode 412 in the second unequal-arm Mach-Zehnder interferometer 410, the operating center wavelength of the filter response is precisely aligned with the wavelength of the optical carrier.

[0121] It is worth noting that the length of the delay line 211 in the first unequal-arm Mach-Zehnder interferometer is different from the length of the delay line 411 in the second unequal-arm Mach-Zehnder interferometer, and therefore the filtering response periods of the two are also different.

[0122] In this example, the free spectral range of the first unequal-arm Mach-Zehnder interferometer is 100 GHz, while the free spectral range of the second unequal-arm Mach-Zehnder interferometer is 20 GHz. This difference in free spectral range provides the technical basis for achieving high-precision and wide-range frequency measurements.

[0123] Step 5: Use a vector network analyzer as a microwave source to sweep the input signal frequency of the optical carrier within the working range of the frequency measuring instrument and record the output power of the two output signals of the first and second instantaneous frequency measurement units 200 and 400 respectively through a multi-channel oscilloscope. Then, divide and compare the output power 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 input signal frequency of different sweeps and the corresponding power ratio to obtain a comparison function relationship, and complete 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.

[0124] By applying a bias voltage from a microwave source to change the frequency of the microwave signals input to the first and second Mach-Zehnder intensity modulators 110 and 210, a 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 is established and a comparison function relationship is constructed. The power ratio is expressed as follows:

[0125] ACF = P up / P down = tan 2 (πn g ΔL / λ)

[0126] P up = sin2 (πn g ΔL / λ)E 2

[0127] P down = cos 2 (πn g ΔL / λ)E 2

[0128] Where ACF is the power ratio, n g is the group refractive index of the fundamental mode in the silicon-based optical chip waveguide, ΔL is the length difference between the upper and lower interference arms of the unequal-arm Mach-Zehnder interferometer, and λ is the wavelength of light input to the unequal-arm Mach-Zehnder interferometer, which is converted by λ as the frequency. 2 is the amplitude of the optical microwave signal when it enters the unequal-arm Mach-Zehnder interferometer, P up 、P down are the output powers at the two output ends of the unequal-arm Mach-Zehnder interferometer.

[0129] The comparative functional relationship between the output power and input signal frequency of the instantaneous frequency measurement unit constructed using an unequal-arm Mach-Zehnder interferometer is demonstrated. The above power ratio relationship proves the power independence, which makes the measurement results of the system unaffected by the input optical power and microwave power.

[0130] The thermally tuned microring resonator is mainly composed 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 the two sides of the heating electrode are connected to the two heating electrode pads through the heating electrode wire.

[0131] The material of the heating electrode is titanium, and the material of the heating electrode wire is copper-aluminum alloy.

[0132] The output spectrum and amplitude comparison function curve of the first instantaneous frequency measurement unit are as follows: Figure 3 As shown, the output spectrum and amplitude comparison function curve of the first instantaneous frequency measurement unit are as follows: Figure 4 shown.

[0133] Step 6: Use a vector network analyzer to generate a microwave signal to be measured, input the microwave signal to be measured into the first and second Mach-Zehnder photoelectric intensity modulators 110 and 210, respectively, to obtain the first and second light-carrying 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 using a multi-channel oscilloscope.

[0134] Step 7: Substitute the real-time output power into the comparison function relationship of the first and second instantaneous frequency measurement units 200 and 400 respectively to calculate and obtain the measured frequency of the microwave signal to be measured.

[0135] Because the first and second instantaneous frequency measurement units have different free spectral ranges, their measurement ranges and accuracies differ. The first instantaneous frequency measurement unit has a larger measurement range, covering half of its free spectral range (i.e., 50 GHz), making it suitable for wide frequency range measurements. The second instantaneous frequency measurement unit, on the other hand, has a smaller spectral period and a relatively narrow measurement range, but offers higher measurement accuracy under the same system noise conditions.

[0136] The measurement frequency of the microwave signal to be measured obtained by the first instantaneous frequency measurement unit 200 is used as the reference measurement frequency, and the one closest to the reference measurement frequency is found 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. In this way, by simultaneously collecting the output results of the two frequency measurement units, it is possible to ensure a wide measurement range while taking into account the requirements of high measurement accuracy.

[0137] In addition, while measuring the frequency of the radar microwave signal, the arrival angle measurement unit can also synchronously monitor the relevant parameters of the radar signal, thereby further enhancing the functionality and application value of the system.

[0138] Step 8: Further add an arrival angle measurement unit to form an arrival angle measurement instrument, and each hot electrode of the arrival angle measurement unit is connected to a multi-path controlled voltage source.

[0139] 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 a thermal tuning unit 101 is added to form a dual parallel Mach-Zehnder intensity modulator 100 .

[0140] Radar signals received by two radar antennas within an optical wavelength of each other are connected to first and second Mach-Zehnder photoelectric intensity modulators, respectively, to form first and second optically-carried microwave signals carrying radar signals, which are microwave signals to be measured. The first and second optically-carried microwave signals are respectively split into two optical signals of equal amplitude through the first Y-branch 102 and the second Y-branch 103. One of the signals is then combined to form a dual-parallel Mach-Zehnder intensity modulator, which is then sent to the angle of arrival measurement unit 300.

[0141] The output of the dual parallel Mach-Zehnder modulator is connected to the arrival angle measurement unit. The input microwave signal can be expressed as:

[0142] V up (t) = V cos(ω RFt)

[0143] V down (t) = V cos(ω RF t + β)

[0144] Step 9: Use the arrival angle measurement module to detect the input optical microwave signal.

[0145] The arrival angle measurement unit 300 receives the optical microwave signal output by the Mach-Zehnder photoelectric intensity modulator and divides it into two parts, the upper sideband and the lower sideband, and outputs them respectively. After passing through the photoelectric detector, they are input into the multi-channel oscilloscope.

[0146] Specifically, firstly by using Figure 2 The multi-path controlled voltage source in the thermally tuned microring 301 controls the thermode 304 to adjust the microring's center wavelength to align with the optical carrier wavelength, further filtering it out and minimizing its impact on subsequent measurements. Next, by controlling the thermode 313 and 314 on the tuned microring-assisted Mach-Zehnder interferometer 310, the wavelength separation of the upper and lower sidebands of the optical microwave signal is achieved. The upper and lower sideband signals are respectively directed to photodetectors 302 and 303 for detection, and the detection results are recorded on an oscilloscope.

[0147] At this time, the upper and lower sidebands of the optical microwave signal can be expressed as:

[0148] P +1 = 2E0 2 J +1 2 (m)[1 + cos(β - α)]

[0149] P -1 = 2E0 2 J -1 2 (m)[1 + cos(β + α)]

[0150] Among them, P +1 is the output power sum of the upper sideband, P -1 is the output power of the lower sideband, E0 is the input optical carrier amplitude, β is the phase difference caused by the distance difference between the two radar antennas, α is the phase difference of the optical 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, which usually corresponds to the space or frequency parameter in physical problems;

[0151] Step 10: By controlling the hot electrode 101 in the dual parallel Mach-Zehnder optoelectronic modulator to change the parameter α, and then by observing the amplitude change on 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 by the parameters of the receiving radar antenna.

[0152] The phase difference of the optical microwave signal is inversely calculated based on the relationship between the output power and phase difference of the upper and lower sidebands, and then the arrival angle is obtained by conversion and calculation based on the phase difference combined with the speed of light and the distance between the antennas.

[0153] Figure 5 (a) to Figure 5 (d) simulates the output signal power changes of the two output channels of the arrival angle measurement unit when the radar antenna receives microwave signals with phase differences of -π / 12, π / 12, -π / 3 and π / 3 respectively.

[0154] In summary, the present invention achieves the simultaneous measurement of radar microwave signal frequency and directional information by combining dual parallel Mach-Zehnder optoelectronic modulators with a frequency measurement unit and an angle-of-arrival measurement unit. This solution boasts a simple structure, high measurement accuracy, a wide measurement range, and excellent stability. In practical engineering applications, the design parameters of the measurement unit can be flexibly adjusted according to specific needs, further improving measurement accuracy and meeting the requirements of diverse application scenarios.

[0155] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A silicon-based integrated device for synchronous measurement of microwave frequency and arrival angle, characterized by: It includes two radar antennas arranged at intervals, connected to the electrical modulation end of the dual-parallel Mach-Zehnder photoelectric intensity modulator, and used for receiving an external microwave signal to be measured and sending it to the dual-parallel Mach-Zehnder photoelectric intensity modulator (100); It includes a dual parallel Mach-Zehnder photoelectric intensity modulator (100) for receiving an optical carrier input from an external light source (5) and loading a microwave signal to be measured from a radar antenna onto the optical carrier, thereby generating two optically-carried microwave signals and sending them to a measurement unit for synchronous measurement of microwave frequency and arrival angle; The device comprises a first instantaneous frequency measurement unit (200), an arrival angle measurement unit (300), and a second instantaneous frequency measurement unit (400), which are connected to the output end of the dual-parallel Mach-Zehnder photoelectric intensity modulator (100) and are used for respectively performing rough frequency measurement, arrival angle measurement, and fine frequency measurement of the light-carrying microwave signal; The measurement units each include a thermally tuned 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 photoelectric intensity modulator via a waveguide. A thermally tuned microring resonator is arranged on the side of 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 two detection modules. A delay line, a thermode or a microring is arranged on the interference arm inside the unequal-arm Mach-Zehnder interferometer.

2. The silicon-based integrated device for synchronous measurement of microwave frequency and arrival angle according to claim 1, characterized in that: The dual-parallel Mach-Zehnder photoelectric intensity modulator (100) is mainly composed of two Mach-Zehnder photoelectric intensity modulators, each Mach-Zehnder photoelectric intensity modulator is provided with two output ends, the four output ends of the two Mach-Zehnder photoelectric intensity modulators are combined into one output end and connected to the angle of arrival measurement unit (300), and the remaining two output ends 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 arrival angle according to claim 1 or 2, characterized in that: The dual-parallel Mach-Zehnder photoelectric intensity modulator (100) comprises a first Mach-Zehnder photoelectric intensity modulator (110), a second Mach-Zehnder photoelectric intensity modulator (120), a hot electrode (101), a first Y branch (102) and a second Y branch (103); The input ends of the first Mach-Zehnder photoelectric intensity modulator (110) and the second Mach-Zehnder photoelectric intensity modulator (120) are connected to the light source (5) through an input Y branch, and the output ends of the first Mach-Zehnder photoelectric intensity modulator (110) and the second Mach-Zehnder photoelectric intensity modulator (120) are respectively divided into two output ends through the first Y branch (102) and the second Y branch (103), and one branch end 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), and the other branch ends of each of the first Y branch (102) and the second Y branch (103) are merged 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 photoelectric intensity modulator divides each output light-carrying microwave signal into two paths with uniform intensity. The two Mach-Zehnder photoelectric intensity modulators output a total of four light-carrying microwave signals, two of which are respectively input to the first and second frequency measurement units (200, 400), and the other two are combined through the combined branch end and input to the arrival angle measurement unit (300). A hot electrode (101) is provided near the collective end of one of the first Y branch (102) and the second Y branch (103), and a voltage is applied to the hot electrode (101) to heat and modulate the phase of the light-carrying microwave signal passing through the Y branch.

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

5. The silicon-based integrated device for synchronous measurement of microwave frequency and arrival angle according to claim 1, characterized in that: The first instantaneous frequency measurement unit (200) comprises a first thermally tuned microring resonator (201), a first unequal-arm Mach-Zehnder interferometer (210), a first detection module (202), and a second detection module (203); an input end of the first unequal-arm Mach-Zehnder interferometer (210) is connected to a first output end of a dual-parallel Mach-Zehnder photoelectric intensity modulator (100) via a waveguide; a first thermally tuned microring resonator (201) is provided on a side of the waveguide at the input end of the first unequal-arm Mach-Zehnder interferometer (210); 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 hot electrode (212) are respectively provided on two interference arms inside the first unequal-arm Mach-Zehnder interferometer (210); The second instantaneous frequency measurement unit (400) comprises a third thermally tuned microring resonator (401), a second unequal-arm Mach-Zehnder interferometer (410), a fifth detection module (402), and a sixth detection module (403); an input end of the second unequal-arm Mach-Zehnder interferometer (410) is connected to a second output end of a dual-parallel Mach-Zehnder photoelectric intensity modulator (100) via a waveguide, a third thermally tuned microring resonator (401) is provided on the side of the waveguide at the input end of the second unequal-arm Mach-Zehnder interferometer (410), two output ends of the second unequal-arm 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 hot electrode (412) are respectively provided on two interference arms inside the first unequal-arm Mach-Zehnder interferometer (210); The arrival angle measurement unit (300) comprises a second thermally tuned microring resonator (301), a microring-assisted unequal-arm Mach-Zehnder interferometer (310), a third detection module (302), and a fourth detection module (303); an input end of the microring-assisted unequal-arm Mach-Zehnder interferometer (310) is connected to a third output end of a dual-parallel Mach-Zehnder photoelectric intensity modulator (100) via a waveguide, and a second waveguide is provided on the side of the waveguide at the input end of the microring-assisted unequal-arm Mach-Zehnder interferometer (310). A thermally tuned microring resonator (301), two output ends of a microring-assisted unequal-arm Mach-Zehnder interferometer (310) are respectively connected to a third detection module (302) and a fourth detection module (303), two interference arms inside the microring-assisted unequal-arm Mach-Zehnder interferometer (310) are respectively provided with a delay line (311) and a microring (312), a thermocouple (314) is provided on the input waveguide side of the delay line (311), and a thermocouple (313) is provided on the side of the microring (312); The length of the delay line (411) of the second instantaneous frequency measurement unit (400) is greater than 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 thermally tuned 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 of the same size, and each thermally tuned microring resonator is provided with a thermoelectrode.

6. A method for synchronously measuring microwave frequency and arrival angle applied to the silicon-based integrated device according to any one of claims 1 to 5, characterized in that: The method measures microwave frequency and arrival angle simultaneously, specifically: Step 1: connecting the silicon-based integrated device to a tunable laser, a radar antenna, a multi-channel oscilloscope, and a multi-channel controlled voltage source respectively; Step 2: Turn on the tunable laser to emit a 1550 nm calibration optical carrier and split the optical carrier into two paths with equal intensity through a Y branch, and send them to the first Mach-Zehnder optoelectronic intensity modulator (110) and the second Mach-Zehnder optoelectronic intensity modulator (120) respectively, to form two optically carried microwave signals of the calibration optical carrier, and adjust the bias voltage so that the first and second Mach-Zehnder optoelectronic intensity modulators operate at the minimum bias point, thereby forming a carrier suppression modulation format; Step 3: The first optical microwave signal is evenly divided into two paths with equal amplitudes through the first Y branch (102), and one path enters the first instantaneous frequency measurement unit; The second optically-carried microwave signal is evenly divided into two paths with equal amplitudes through the second Y branch (103), and one path enters the second instantaneous frequency measurement unit; Step 4: Using a multi-channel voltage source to control the thermally tuned microring resonators (201, 401) in the first and second instantaneous frequency measurement units (200, 400); Step 5: using a microwave source to sweep the frequency within the working range to control the frequency of the optically carried microwave signal and respectively record the output power of the two output signals of the first and second instantaneous frequency measurement units (200, 400) through a multi-channel oscilloscope, then comparing the output power of the two output signals of each instantaneous frequency measurement unit at each swept input microwave signal frequency to obtain a power ratio, fitting and establishing a relationship between the input microwave signal frequency of different swept frequencies and the corresponding power ratio for each instantaneous frequency measurement unit to obtain a comparison function relationship, and completing the calibration work; Step 6: inputting the microwave signal to be measured into the first and second Mach-Zehnder photoelectric intensity modulators (110, 210) to obtain first and second light-carrying microwave signals of the microwave signal to be measured, respectively, and then inputting them into the first and second instantaneous frequency measurement units (200, 400), respectively, and recording the real-time output power of the first and second instantaneous frequency measurement units (200, 400) using a multi-channel oscilloscope; Step 7: Substituting the real-time output power into the respective comparison function relationships of the first and second instantaneous frequency measurement units (200, 400) to calculate and obtain the measured frequency of the microwave signal to be measured; Step 8: The radar signals received by the two radar antennas are connected to the first and second Mach-Zehnder photoelectric intensity modulators, respectively, to form the first and second optically-carried microwave signals of the microwave signal to be measured; The first optical microwave signal and the second optical microwave signal are respectively divided into two optical signals with equal amplitudes through the first Y branch (102) and the second Y branch (103), and one optical signal is taken from each signal and then beam-combined and sent to the arrival angle measurement unit (300); Step 9: the arrival angle measurement unit (300) receives the light-carrying microwave signal output by the Mach-Zehnder photoelectric intensity modulator and divides it into two parts, the upper sideband and the lower sideband, and outputs them respectively, and then inputs them into a multi-channel oscilloscope after passing through a photoelectric detector; Step 10: Adjust the thermally tuned microring resonator laid on one arm waveguide of the dual parallel Mach-Zehnder optoelectronic intensity modulator to change the phase difference between the upper and lower sidebands of the optical microwave signal output by the two arms, and obtain the arrival angle of the radar microwave signal by recording the waveform on a multi-channel oscilloscope.

7. The method for synchronously measuring microwave frequency and arrival angle according to claim 6, wherein: In step 5, by changing the frequency of the microwave signals input to the first and second Mach-Zehnder photoelectric intensity modulators (110, 210), the relationship between the power ratio between the two output powers of the first and second instantaneous measurement units (200, 400) and the input signal frequency is established and a comparison function relationship is constructed by fitting. 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 silicon-based optical chip waveguide, ΔL is the length difference between the upper and lower interference arms of the unequal-arm Mach-Zehnder interferometer, λ is the wavelength of the light input to the unequal-arm Mach-Zehnder interferometer, and E 2 is the amplitude of the optical microwave signal when it enters the unequal-arm Mach-Zehnder interferometer, P up 、P down are the output powers at the two output ends of the unequal-arm Mach-Zehnder interferometer.

8. The method for synchronously measuring microwave frequency and arrival angle according to claim 6, wherein: 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 a final accurate measurement frequency.

9. The method for synchronously measuring microwave frequency and arrival angle according to claim 6, wherein: 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 the 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 output power sum of the upper sideband, P -1 is the output power of the lower sideband, E0 is the input optical carrier amplitude, β is the phase difference caused by the distance difference between the two radar antennas, α is the phase difference of the optical 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; 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 is inferred based on the phase difference, and the arrival angle is obtained by conversion and calculation based on the radar separation distance.

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