A time-domain balanced zero-beat detection device based on silicon-based optoelectronic chip

Abstract

The present invention discloses a time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip, which can be used to precisely measure the orthogonal components of a pulsed coherent state light field with an intensity at the photon number level. The device comprises three parts: a high numerical aperture optical fiber array, a silicon-based optoelectronic chip and a peripheral circuit. The high numerical aperture optical fiber array is connected to the silicon-based optoelectronic chip by end-face coupling, and the signal light and the local light can be introduced into the silicon-based chip. The silicon-based chip comprises two end-face couplers, a 50 / 50 multimode interference coupler, two optical attenuators, and two germanium photodiodes. The peripheral circuit provides the precision voltage source and low-noise amplifier circuit required for the operation of the chip. The detection device has the advantages of small size, low power consumption, low cost, high precision, and good stability.

Description

Technical Field

[0001] The present invention relates to the field of continuous variable quantum information, and in particular to a time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip that can be used to precisely measure orthogonal components of a pulsed coherent state light field with an intensity at the photon number level. Background Art

[0002] Balanced zero-beat detection devices can measure the orthogonal components of the light field and are widely used in quantum information fields such as quantum communication, quantum tomography, quantum computing, and quantum precision measurement. The detection device can be mainly divided into two types: frequency domain and time domain. The time domain detection device can directly measure the orthogonal components of the pulse light field without the need for frequency sideband technology. At the same time, the detection device has the advantages of being compatible with photon counting detection technology and accurately measuring the orthogonal components of the pulse light field with an intensity of the photon number level, but it needs to have a high common mode rejection ratio. In quantum information experiments of free space and optical fiber devices, two photodiodes with consistent responses and optical fiber bending attenuation are usually used to achieve a high common mode rejection ratio of the detection device. However, due to the limitations of silicon-based optoelectronic chip technology, silicon-based optoelectronic chip technology is compatible with CMOS technology, and optoelectronic devices are integrated on silicon-based chips on a large scale using processes such as lithography, doping, and etching. Therefore, the above technology is not suitable for integrated silicon-based optoelectronic chips.

[0003] In the existing related technical research, the literatures "Silicon photonics interfaced with integrated electronics for 9GHz measurement of squeezed light. Nature Photonics, 15(1), 11-15(2021)" and "Integrated balanced homodyne photonic–electronic detector for beyond 20GHz shot-noise-limited measurements. Optica, 8(9), 1146-1152(2021)" only report on the frequency domain balanced zero-beat detector based on silicon-based optoelectronic chips. However, there are currently no reports on the specific implementation of the technical solution of the time domain balanced zero-beat detection device based on silicon-based optoelectronic chips. The silicon-based optoelectronic chips mentioned in the above two documents use vertical coupling technology of signal light and local light, but this coupling loss is large, resulting in low detection efficiency of the detector; in addition, in the double-arm balancing process, an MZ interferometer based on a thermal phase shifter is introduced to attenuate the light field. During the attenuation process, it has the disadvantages of extinction point drift, unstable attenuation, poor accuracy, and difficulty in achieving subsequent double-arm automatic balancing. Therefore, the design of the above chip is not suitable for time-domain balanced zero-beat detection technology based on silicon-based optoelectronic chips. Summary of the invention

[0004] The present invention aims at the technical defects of the existing time-domain balanced zero-beat detection devices in the application of silicon-based optoelectronic chips in the background technology and the detection efficiency problems of the time-domain balanced zero-beat detection devices, so as to achieve precise measurement of the orthogonal components of the pulse light field with an intensity at the level of photons. The detection device disclosed in the present invention introduces the signal light and the local light into the silicon-based optoelectronic chip in an end-face coupling manner, thereby achieving lower coupling loss; at the same time, based on the carrier absorption effect, a PIN phase modulator is used to achieve precise and stable adjustment of the light intensity of the two output arms on the chip, thereby achieving a high common-mode rejection ratio on the chip. Based on the above theoretical analysis of feasibility and experimental verification, the present invention uses the technology on silicon-based integrated circuits to design, manufacture, and package optical devices and optoelectronic integrated circuits, thereby achieving a breakthrough in cost, volume, and power consumption. To this end, the present invention provides a time-domain balanced zero-beat detection device based on silicon-based optoelectronic chips.

[0005] In order to achieve the expected effects of the theoretical analysis and experimental verification of the above technical scheme, the present invention adopts the following technical scheme: a time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip, comprising an optical fiber array, which comprises a first polarization-maintaining optical fiber connector and a second polarization-maintaining optical fiber connector, and the two optical fiber connection ends are respectively connected to each other through a first optical fiber and a second optical fiber. In addition, the above-mentioned time-domain balanced zero-beat detection device also includes a silicon-based optoelectronic chip and a peripheral circuit connected to each other in a metal shielding cover, the silicon-based optoelectronic chip includes a first end face coupler and a second end face coupler connected to the optical fiber connection end by light curing, the first end face coupler and the second end face coupler are respectively connected to the incident end of a 50 / 50 multimode interference coupler, and the two optical signals are interfered by the 50 / 50 multimode interference coupler. The optical signal is divided into two paths, wherein one path of the optical signal is converted into a photocurrent signal after passing through the first optical attenuator and the first germanium photodiode in sequence, and the other path of the optical signal is converted into another photocurrent signal after passing through the second optical attenuator and the second germanium photodiode in sequence. The two photocurrent signals are output after subtraction. The first adjustable bias voltage source, the second adjustable bias voltage source, the third adjustable bias voltage source, and the fourth adjustable bias voltage source are respectively arranged at the two ends of the first optical attenuator, the second optical attenuator, the first germanium photodiode, and the second germanium photodiode. The peripheral circuit includes a charge amplifier circuit for integrating the photocurrent signals after the two paths are subtracted. The integrated photocurrent signal is converted into a Gaussian pulse photocurrent signal after passing through a shaping amplifier circuit and is output by a radio frequency interface. The radio frequency interface is arranged on a metal shielding cover.

[0006] As a further limitation and explanation of the above embodiment, the first optical fiber and the second optical fiber are both high numerical aperture polarization maintaining optical fibers, and the numerical aperture NA thereof matches the mode field diameter of the first end face coupler and the second end face coupler.

[0007] As a further limitation and explanation of the above embodiment, the first end face coupler and the second end face coupler are both inverted tapered end face couplers, which respectively convert the closed mode in the silicon-based waveguide into an optical fiber mode, thereby solving the mode matching and refractive index matching problems and further reducing coupling losses.

[0008] As a further limitation and explanation of the above-mentioned embodiment, the attenuation principle of the first optical attenuator and the second optical attenuator is based on the absorption effect of carriers on the light field, and both adopt PIN-type phase modulators, and adjustable forward bias voltages are applied to both ends by the first adjustable bias voltage source and the second adjustable bias voltage source respectively, thereby achieving precise adjustment of the light intensity by one ten-thousandth.

[0009] As a further limitation and explanation of the above embodiment, the first germanium photodiode and the second germanium photodiode adopt the process of epitaxial growth of germanium on a silicon substrate, and are PIN-type detectors, and adjustable reverse bias voltages are applied to both ends of the two diodes by a third adjustable bias voltage source and a fourth adjustable bias voltage source, respectively.

[0010] As a further limitation and explanation of the above embodiment, the charge amplifier circuit adopts a charge amplifier, wherein the inverting input terminal of the charge amplifier is connected to the input capacitor C i and a feedback resistor R is connected between its inverting input terminal and output terminal. f , the feedback resistor R f There is a feedback capacitor C in parallel f , the non-inverting input of the charge amplifier is grounded, and the input capacitor C i The other electrode and the input resistor R i One end is connected to the input resistor R i The other end is grounded, and the photocurrent signal after subtraction of the two photodiodes passes through the input resistor R i , input capacitor C i Extract the AC pulse signal with a frequency higher than 100 Hz, and then the feedback capacitor C of the charge amplifier f The feedback resistor R f It has the function of providing DC working point and discharge. After integration, the charge amplifier outputs a pulse signal whose peak value satisfies V peak =Q / C f The relationship between Q and C is shown in Figure 2, where Q is the total charge of a single photocurrent pulse, the rise time of the output electrical pulse is the integration time of the charge amplifier, which is greater than or equal to the duration of the signal pulse, and the fall time of the output electrical pulse after integration is τ = C f ·R f .

[0011] As a further limitation and explanation of the above embodiment, the shaping amplifier circuit includes three parts: a high-pass filter, a voltage amplifier and a low-pass filter, wherein the high-pass filter with a cut-off frequency of 2.5MHz includes a first capacitor C1, one electrode of the first capacitor C1 is connected to the output end of the charge amplifier, and the other electrode of the first capacitor C1 is sequentially connected to a first resistor R1 and a first inductor L1 and grounded, and a third-order π-type Butterworth low-pass filter with a cut-off frequency of 6MHz includes a second inductor L2, and its two ends are grounded through a second capacitor C2 and a third capacitor C3, respectively, and a common end of the first capacitor C1 and the first resistor R1 is connected to the same end of the voltage amplifier through a fourth resistor R4. The phase input ends are connected, the inverting input end of the voltage amplifier is connected to the third resistor R3 and grounded, and a second resistor R2 is connected between the inverting input end and the output end thereof, the output end of the voltage amplifier is connected to the common end of the second inductor L2 and the second capacitor C2, the integrated photocurrent signal passes through a high-pass filter with a cut-off frequency of 2.5MHz to shorten the electric pulse fall time from the microsecond level τ to the hundred nanosecond level, the photocurrent pulse signal output by the high-pass filter is input into the voltage amplifier for in-phase amplification, the amplified pulse signal passes through a third-order π-type Butterworth low-pass filter with a cut-off frequency of 6MHz, which helps to smooth the pulse peak and shape the output pulse signal into a Gaussian pulse signal.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] 1. The time-domain balanced zero-beat detection device designed in the present invention adopts silicon-based optoelectronic integration technology. Compared with free space and optical fiber devices, it has the advantages of small size, low power consumption, and low cost, and can promote the large-scale application of quantum information technologies such as quantum communication.

[0014] 2. The time-domain balanced zero-beat detection device designed in the present invention can introduce the signal light and the local light into the silicon-based optoelectronic chip through a high numerical aperture optical fiber in an end-face coupling manner, thereby achieving a relatively low coupling loss of about 2 dB.

[0015] 3. The time-domain balanced zero-beat detection device designed in the present invention is based on the carrier absorption effect and uses a PIN phase modulator to achieve precise and stable adjustment of the light intensity of the two output arms on the chip. The adjustment accuracy can reach more than one hundred thousandth, achieving a high common-mode rejection ratio on the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A structural connection diagram of an embodiment of the present invention

[0017] Figure 2 1 is a circuit schematic diagram of a charge amplifier circuit and a shaping amplifier circuit in an embodiment of the present invention;

[0018] Figure 3The attenuation characteristics and volt-ampere characteristics curves of two optical attenuators on a silicon-based optoelectronic chip in an embodiment of the present invention are shown;

[0019] Figure 4 is a trajectory diagram of vacuum field shot noise in an embodiment of the present invention;

[0020] Figure 5 A schematic diagram of a linear response test result of an embodiment of the present invention;

[0021] Figure 6 A schematic diagram of the optical pulse resolution test results of an embodiment of the present invention;

[0022] Figure 7 A schematic diagram of stability test results of an embodiment of the present invention.

[0023] In the figure: the optical fiber array is 1, the silicon-based optoelectronic chip is 2, the peripheral circuit is 3, the metal shielding cover is 4, the first polarization-maintaining optical fiber connector is 5, the second polarization-maintaining optical fiber connector is 6, the first optical fiber is 7, the second optical fiber is 8, the optical fiber connection end is 9, the first end face coupler is 10, the second end face coupler is 11, the 50 / 50 multimode interference coupler is 12, the first optical attenuator is 13, the second optical attenuator is 14, the first germanium photodiode is 15, the second germanium photodiode is 16, the charge amplifier circuit is 17, the shaping amplifier circuit is 18, the first adjustable bias voltage source is 19, the second adjustable bias voltage source is 20, the third adjustable bias voltage source is 21, the fourth adjustable bias voltage source is 22, and the radio frequency interface is 23. DETAILED DESCRIPTION

[0024] In order to further illustrate the technical solution of the present invention, within the protection scope of the above invention content, we further illustrate the specific implementation of the present invention by selecting the best embodiment.

[0025] As attached Figure 1As shown, the optical fiber array 1 and silicon-based optoelectronic chip 2 used in this embodiment are suitable for optical fields in communication bands such as O-band and C-band. The first polarization-maintaining optical fiber connector 5 and the second polarization-maintaining optical fiber connector 6 use universal FC / APC connectors. The first optical fiber 7 and the second optical fiber 8 have a pigtail length of 1m and a numerical aperture of 0.45. The silicon-based optoelectronic chip 2 is manufactured using a standard silicon-based optoelectronic process, and the size of the optical path portion is 1.5mm×0.4mm; the optical fiber connection end 9 is connected to the first end face coupler 10 and the second end face coupler 11 by UV glue light curing, wherein The first end face coupler 10 and the second end face coupler 11 are inverted tapered end face couplers with an end face size of 0.14um×0.22um, a device length of 20um, and a mode field diameter of 4um. They can convert the closed mode in the silicon-based waveguide into an optical fiber mode, thereby solving the mode matching and refractive index matching problems and reducing the coupling loss. After the high numerical aperture optical fiber array 1 and the silicon-based optoelectronic chip 2 are packaged, the connection loss is about 2dB. The silicon-based optoelectronic chip 2 and the peripheral circuit 3 are bonded with 25um gold wire, and both are placed in a well-shielded aluminum alloy box.

[0026] In the experiment, the mode field diameter of the silicon-based waveguide was 0.4-0.5um. After passing through the inverted tapered end coupler, the mode field diameter was changed to 4um. The fiber array uses a high numerical aperture fiber with a numerical aperture NA of 0.45, and its mode field diameter is about 3.5um, which matches the mode field diameter at the incident end of the inverted tapered end coupler to achieve low coupling loss.

[0027] During the detection experiment, the local light field is a 1550nm pulse laser with a repetition rate of 1MHz, a pulse width of 100ns, and an extinction ratio greater than 40dB, and the signal light field is a vacuum field. The two are input into the silicon-based time-domain balanced zero-beat device through the first polarization-maintaining fiber connector 5 and the second polarization-maintaining fiber connector 6. The signal light and the local light interfere with each other in the 50 / 50 multimode interference coupler 12. After the interference, the outputs of the two arms are respectively connected to the first optical attenuator 13, the second optical attenuator 14 and the two connected first germanium photodiodes 15 and second germanium photodiodes 16. The optical signal is converted into an electrical signal by the germanium photodiode and subtracted, and then integrated by the charge amplifier circuit 17; the integrated electrical signal is converted into a Gaussian pulse signal after passing through the shaping amplifier circuit 18, and finally output through the radio frequency interface 23, and the full width of the output pulse is 200ns. In the above implementation, the first adjustable bias voltage source 19 and the second adjustable bias voltage source 20 preferably use B2961A of De Technology, which has the characteristics of low noise and high resolution and is used to adjust the light intensity balance of the two output optical paths. The third adjustable bias voltage source 21 and the fourth adjustable bias voltage source 22 respectively use adjustable voltage stabilizing modules LM317 / LM337, which can fine-tune the optical path lengths of the two output optical paths, and the radio frequency interface 23 uses an SMA interface.

[0028] like Figure 2 As shown in FIG. 1 , the circuit principle of the charge amplifier circuit 17 and the shaping amplifier circuit 18. In the charge amplifier circuit 17, the core device is a low-noise operational amplifier ADA4817, and the input resistor R i The input capacitance C is 10MΩ. i is 100pF, the feedback capacitor C f is 1pF, the feedback resistor R f In the shaping circuit 18, the circuit includes three parts: a high-pass filter, a voltage amplifier and a low-pass filter. The core device of the voltage amplifier is the operational amplifier OPA847, in which the first capacitor C1 = 2.2nF, the first resistor R1 = 30Ω and the first inductor L1 = 5.6uH constitute a high-pass filter with a cut-off frequency of 2.5MHz; the second capacitor C2 = 560pF, the second inductor L2 = 1.5uH and the second capacitor C3 = 560pF constitute a third-order π-type Butterworth low-pass filter with a cut-off frequency of 6MHz; the feedback resistors R2 = 1kΩ and R3 = 50Ω at both ends of the voltage amplifier OPA847 transimpedance amplifier, the amplification factor is 20 times, and the fourth resistor R4 = 50Ω is matched.

[0029] As attached Figure 3 As shown, the time-domain balanced zero-beat detection device in this embodiment has a higher common mode rejection ratio, that is, the attenuation accuracy requirements of the first optical attenuator 13 and the second optical attenuator 14 are relatively high. Figure 3 In the figure, the curves formed by the solid squares and the triangle points respectively represent the characteristics of the attenuation amplitude of the first optical attenuator 13 and the second optical attenuator 14 as the voltage at both ends changes. When the voltage range is 0–1.1V, the adjustable attenuation range of the optical attenuator is about 0–83.6% and 0–84%, and the current range is 0–9.56mA and 0–9.74mA (less than the damage threshold current 10mA), and the two characteristic curves are basically consistent. By observing the curve, it can be concluded that when the applied voltage is larger, the attenuation of the optical attenuator is more sensitive to the change of voltage, that is, the required voltage accuracy is higher. Generally, the error of the two output arms of the 50 / 50MMI coupler is less than 5%. It can be seen from Table 1 that the voltage amplitude of 0.8V is sufficient to compensate for the error caused by the imbalance of the two arms. In the interval of 0.75V to 0.8V, the attenuation accuracy is calculated to be one in ten thousand, and the required control voltage accuracy is about 10μV. The output voltage accuracy of Keysight's B2961A is 0.1μV, which is sufficient to control the two arms to achieve high-precision balance.

[0030] Table 1

[0031]

[0032] Based on the above optical attenuator characteristics, it can be ensured that the detection device achieves a high common mode rejection ratio. The following is the performance test result of the time domain balanced zero-beat detection device.

[0033] As attached Figure 4 As shown, the detector output waveform is good and the common mode rejection ratio is high. After testing, the common mode rejection ratio can reach 70dB. The instrument used to collect the waveform is the oscilloscope Tektronix MSO 5204B.

[0034] As attached Figure 5 As shown, the detector output pulse peak voltage is collected. The solid square line represents the noise fluctuation variance of the detected peak voltage, the solid circle line represents the noise fluctuation variance of the detector electronics, and the red triangle represents the vacuum shot noise fluctuation variance. It is obvious that the detector has good linear response characteristics. After testing, its detection efficiency is 0.38 and the gain is 4.23×10 -6 / Photon.

[0035] As attached Figure 6 As shown in the figure, to ensure that each light field pulse is uncorrelated with other pulses, we observe the pulse resolution of the detection device by studying the correlation coefficient of the pulse peak. When m = 0, it means that the two pulses are completely correlated. When m ≠ 0, there is no correlation between the pulses. By evaluating the correlation coefficient, it can be concluded that there is no correlation between any two adjacent pulses.

[0036] As attached Figure 7 As shown, the pulse peak voltage is continuously collected for 100s at a repetition rate of 1kHz, the sampling point is 100K, and the Allan variance is calculated to obtain a single measurement without calibration time of 4s. The detection device has good stability.

[0037] The above theoretical analysis and experimental verification are sufficient to prove that compared with the existing time-domain balanced zero-beat detection device, the present invention has the advantages of small coupling loss and high detection efficiency, and achieves the purpose of high common mode rejection ratio on chip. At the same time, during the attenuation process, it has the characteristics of stable attenuation, good precision, and easy to achieve subsequent double-arm automatic balance.

[0038] The above shows and describes the main features and advantages of the present invention. For those skilled in the art, it is obvious that the specific implementation of the present invention is not limited to the details of the above exemplary embodiments, and the creative ideas and design ideas of the present invention can be realized in other specific forms without departing from the spirit or basic features of the present invention, which should be equivalent to the protection scope disclosed in the technical solution of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

[0039] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip, comprising an optical fiber array (1), comprising a first polarization-maintaining optical fiber connector (5) and a second polarization-maintaining optical fiber connector (6), and an optical fiber connection end (9) connected to the first optical fiber (7) and the second optical fiber (8), respectively, characterized in that: The invention also comprises a silicon-based optoelectronic chip (2) and a peripheral circuit (3) which are arranged in a metal shielding cover (4) and connected to each other. The silicon-based optoelectronic chip (2) comprises a first end face coupler (10) and a second end face coupler (11) which are connected to the optical fiber connection end (9) by light curing. The first end face coupler (10) and the second end face coupler (11) are respectively connected to the incident end of a 50 / 50 multimode interference coupler (12). Two optical signals are separated into two paths after interference by the 50 / 50 multimode interference coupler (12). One optical signal is converted into a photocurrent signal after passing through a first optical attenuator (13) and a first germanium photodiode (15) in sequence. The other optical signal is converted into a photocurrent signal after passing through a second optical attenuator (14) and a second germanium photodiode (16) in sequence. 16) is converted into another photocurrent signal, and the two photocurrent signals are output after being subtracted from each other. A first adjustable bias voltage source (19), a second adjustable bias voltage source (20), a third adjustable bias voltage source (21), and a fourth adjustable bias voltage source (22) are respectively arranged at the two ends of the first optical attenuator (13), the second optical attenuator (14), the first germanium photodiode (15), and the second germanium photodiode (16). The peripheral circuit (3) includes a charge amplifier circuit (17) for integrating the photocurrent signals after the two subtractions. The integrated photocurrent signal is converted into a Gaussian pulse photocurrent signal after passing through a shaping amplifier circuit (18) and is output by a radio frequency interface (23). The radio frequency interface (23) is arranged on the metal shielding cover (4).

2. The time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip according to claim 1, characterized in that: The first optical fiber (7) and the second optical fiber (8) are both high numerical aperture polarization-maintaining optical fibers, and the numerical apertures NA thereof match the mode field diameters of the first end face coupler (10) and the second end face coupler (11).

3. The time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip according to claim 1, characterized in that: The first end face coupler (10) and the second end face coupler (11) are both inverted tapered end face couplers, which respectively convert the closed mode in the silicon-based waveguide into an optical fiber mode, thereby solving the problems of mode matching and refractive index matching, and further reducing coupling loss.

4. The time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip according to claim 3, characterized in that: The attenuation principle of the first optical attenuator (13) and the second optical attenuator (14) is based on the absorption effect of carriers on the light field. Both adopt PIN-type phase modulators, and adjustable forward bias voltages are applied to the two ends of the first optical attenuator (19) and the second optical attenuator (20) respectively, thereby achieving precise adjustment of the light intensity by one ten-thousandth.

5. The time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip according to claim 4, characterized in that: The first germanium photodiode (15) and the second germanium photodiode (16) are produced by epitaxially growing germanium on a silicon substrate and are PIN-type detectors. Adjustable reverse bias voltages are applied to both ends of the first germanium photodiode (15) and the second germanium photodiode (16) by a third adjustable bias voltage source (21) and a fourth adjustable bias voltage source (22), respectively.

6. A time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip according to any one of claims 1 to 5, characterized in that: The charge amplifier circuit (17) adopts a charge amplifier, wherein the inverting input terminal of the charge amplifier is connected to the input capacitor C i and a feedback resistor R is connected between its inverting input terminal and output terminal. f , the feedback resistor R f There is a feedback capacitor C in parallel f , the non-inverting input of the charge amplifier is grounded, and the input capacitor C i The other electrode and the input resistor R i One end is connected to the input resistor R i The other end is grounded, and the photocurrent signal after subtraction of the two photodiodes passes through the input resistor R i , input capacitor C i Extract the AC pulse signal with a frequency higher than 100 Hz, and then the feedback capacitor C of the charge amplifier f The feedback resistor R f It has the function of providing DC working point and discharge. After integration, the charge amplifier outputs a pulse signal whose peak value satisfies V peak =Q / C f The relationship between the output pulse and the charge amplifier is shown in Figure 2, where Q is the total charge of a single photocurrent pulse, the rise time of the output pulse is the integration time of the charge amplifier, which is greater than or equal to the duration of the signal pulse, and the fall time of the output pulse after integration is τ = C f ·R f .

7. The time-domain balanced zero-beat detection device based on a silicon-based optoelectronic chip according to claim 6, characterized in that: The shaping amplifier circuit (18) comprises three parts: a high-pass filter, a voltage amplifier and a low-pass filter, wherein the high-pass filter with a cut-off frequency of 2.5 MHz comprises a first capacitor C1, one electrode of the first capacitor C1 is connected to the output end of the charge amplifier, the other electrode of the first capacitor C1 is sequentially connected to a first resistor R1 and a first inductor L1 and is grounded, and the third-order π-type Butterworth low-pass filter with a cut-off frequency of 6 MHz comprises a second inductor L2, and two ends of the second inductor L2 are respectively grounded through a second capacitor C2 and a third capacitor C3, and a common end of the first capacitor C1 and the first resistor R1 is connected to the in-phase input end of the voltage amplifier through a fourth resistor R4. The inverting input terminal of the voltage amplifier is connected to the third resistor R3 and grounded, and a second resistor R2 is connected between the inverting input terminal and the output terminal thereof, and the output terminal of the voltage amplifier is connected to the common end of the second inductor L2 and the second capacitor C2. The integrated photocurrent signal passes through a high-pass filter with a cutoff frequency of 2.5 MHz to shorten the electric pulse fall time from the microsecond level τ to the hundred nanosecond level. The photocurrent pulse signal output by the high-pass filter is input into the voltage amplifier for in-phase amplification. The amplified pulse signal passes through a third-order π-type Butterworth low-pass filter with a cutoff frequency of 6 MHz, which helps to smooth the pulse peak and shape the output pulse signal into a Gaussian pulse signal.

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