Miniaturized time domain modulation signal detection device

Abstract

The invention discloses a miniaturized time domain modulation signal detection device, which comprises a high-speed photodiode, a low noise amplifier, a detector, a comparator, a trigger, a digital-to-analog converter, an FPGA (Field Programmable Gate Array) and a computer, the input end of the high-speed photodiode is connected with signal light to be detected, the output end of the high-speed photodiode is connected with the input end of the low-noise amplifier, the output end of the low-noise amplifier is connected with the input end of the detector, the output ends of the detector and the digital-to-analog converter are respectively connected with two comparison ends of the comparator, and the output end of the comparator is connected with the input end of the trigger. And the input and output end of the trigger is connected with the FPGA. According to the invention, detection and discrimination of the time domain modulation signal are realized, and automatic, low-cost and real-time detection and discrimination of the time domain modulation signal of the monitoring point can be realized, so that the cost and the workload of operators are greatly reduced, and the detection efficiency of the time domain modulation signal is improved.

Description

Technical Field

[0001] The present invention relates to a periodically modulated signal, and particularly to a detection device for a miniaturized time-domain modulated signal. Background Art

[0002] In the field of high-power lasers, especially in large-scale high-power lasers applied in inertial confinement fusion technology, phase modulation is used to increase the laser spectral bandwidth, reduce the stimulated Brillouin scattering (SBS) effect on large-aperture optical elements in subsequent high-power systems, ensure the safe operation of large-aperture optical elements, and at the same time be able to suppress the stimulated Raman scattering (SRS) effect during the laser target shooting process and improve the beam homogenization effect. This broadens the laser spectrum. When the broadened spectrum is transmitted in a large-scale laser device, due to the combined effects of group velocity dispersion, polarization mode dispersion in the optical fiber, and the non-uniform gain spectrum of the gain medium, etc., the broadened spectrum is affected by non-uniform spectral transmittance in the laser device, resulting in different transmittances for lights of different frequencies in the laser device, thereby causing a part of the frequency modulation of the laser to be converted into periodic amplitude modulation in the time domain. This phenomenon is called the amplitude-frequency modulation effect in high-power lasers.

[0003] The existence of the amplitude-frequency modulation effect poses a potential threat to the operation stability of high-power laser devices and the fidelity performance of the time-power curve. Therefore, it is particularly important to detect and distinguish this effect in a timely and accurate manner. However, most of the existing detection technologies rely on high-speed oscilloscopes for signal sampling. For example, in the detection device for amplitude-frequency modulation signals in patent document CN

[0004] 105356938A, although it can detect the time-domain modulation amount of the signal light and solve the problem of remote multi-point monitoring, it requires optoelectronic-optical conversion and multiple amplifiers for waveform replication. At the same time, the system uses high-speed oscilloscope sampling. These measures greatly increase the complexity and cost of the monitoring system, increase the instability of the system, and it is difficult to achieve the miniaturization and integration of the monitoring system. Summary of the Invention

[0005] To overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a detection device for time-domain modulated signals, solve the problems of low detection accuracy, high detection cost, complex monitoring system, and low integration degree existing in the current detection process, and realize the function of low-cost detection and discrimination of time-domain modulated signals in laser devices.

[0006] The technical solution of the device of the present invention is as follows:

[0007] A detection device for time-domain modulated signals, characterized in that it includes a high-speed photodiode, a low-noise amplifier, a detector, a comparator, a trigger, a digital-to-analog converter, an FPGA, and a computer;

[0008] The input end of the described high-speed photodiode receives the signal light to be measured, and the output end is connected to the input end of the described low-noise amplifier. The low-noise amplifier amplifies the time-domain modulated signal, and the output end is connected to the input end of the detector. The output ends of the detector and the digital-to-analog converter are respectively connected to two input ends of the comparator, and the output of the comparator is connected to the input end of the flip-flop.

[0009] The output end and the reset end of the described flip-flop are connected to the described FPGA. The FPGA is connected to the input end of the digital-to-analog converter, and the FPGA is also connected to the computer through a serial port.

[0010] The signal light to be measured enters the high-speed photodiode. The high-speed photodiode responds to the amplitude of the signal light to be measured, and the waveform of the output electrical signal is similar to the waveform of the signal light to be measured. The electrical signal is amplified by the described low-noise amplifier and enters the detector for detection to obtain the modulation degree signal of the time-domain modulated signal. The output of the detector is connected to one input end of the comparator, and the output of the digital-to-analog converter is connected to the other end of the comparator to realize the comparison of the detector signal. The output end of the comparator is connected to the input end of the described flip-flop to realize the triggering of the time-domain modulated signal. The output end and the reset end of the flip-flop are connected to the described FPGA. The FPGA is connected to the input end of the digital-to-analog converter, and the FPGA is also connected to the computer through a serial port to display the current time-domain modulation amount in real time.

[0011] The operating frequency range of the described detector is 2 - 67 GHz, and the input power range is -25 dBm to 15 dBm.

[0012] The propagation delay of the described comparator is 150 ps, and the minimum pulse width is 80 ps.

[0013] The computer is connected to the FPGA through a serial port to display and analyze the time-domain modulation amount data transmitted by the FPGA in real time.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] Through the low-noise amplifier, detector, comparator, flip-flop, digital-to-analog converter and FPGA, the miniaturization and integration of the monitoring system are realized, avoiding the high cost and poor maintainability problems brought by using a high-speed oscilloscope. The present invention has the characteristics of low cost, high flexibility, high stability and being conducive to expansion.

[0016] The present invention adopts the combination of a high-speed photodiode and a low-noise amplifier to realize the efficient conversion and amplification of the signal light; adopts the combination of a high-frequency detector and a comparator to realize the precise detection and processing of the amplified signal; introduces the combination of a flip-flop and an FPGA to realize the fast capture and processing of the laser short-pulse signal. Description of the Drawings

[0017] Figure 1 is a schematic diagram of the detection device for the time-domain modulation signal of the present invention.

[0018] Figure 2 is the flowchart of the operation of the detection device for the time-domain modulation signal of the present invention.

[0019] Figure 3 is a graph showing the relationship between the time-domain modulation degree and the detector voltage in the experimental results of Embodiment 1 of the present invention.

[0020] Figure 4 is a tracking and monitoring graph of the time-domain modulation degree and the detector voltage in the experimental results of Embodiment 1 of the present invention. Detailed Embodiment

[0021] The embodiments of the present invention will be described in detail below in conjunction with the drawings: These embodiments are implemented on the premise of the technical solution of the present invention, and specific implementation methods are given, but the protection scope of the present invention is not limited to the following embodiments.

[0022] Please refer to Figure 1 , Figure 1 is a schematic diagram of the detection device for the time-domain modulation signal of the present invention. As shown in the figure, it consists of the following parts:

[0023] A high-speed photodiode 1, as the front-end sensor of the device, receives the signal light to be measured at its input end. The high-speed photodiode can respond to the amplitude of the signal light to be measured related to time and convert it into an electrical signal for output. The waveform of this electrical signal is similar to the waveform of the signal light to be measured;

[0024] A low-noise amplifier 2, with an operating frequency of 18 - 26.5 GHz, a gain of 40 dB, a noise figure of 2.4 dB, and a P-1dB power of 10 dBm, amplifies the electrical signal output by the high-speed photodiode to improve the signal-to-noise ratio of the signal. The amplified signal still retains the characteristics of time-domain modulation.

[0025] A detector 3, with an operating frequency of 2 - 67 GHz, an input power range of -25 dBm to 15 dBm, and a propagation delay of 1.3 ns (falling edge) at 10 dBm, performs detection processing on the amplified time-domain modulation signal to obtain a modulation degree signal;

[0026] A comparator 4, with a propagation delay of 150 ps and a pulse width of 80 ps (minimum), compares the square-wave signal output by the detector with the level signal output by the digital-to-analog converter. The output of the comparator is used to trigger a flip-flop;

[0027] The trigger 5 has rise and fall times of 35 ps and a maximum input clock of 10 GHz. Triggered by the output signal of the comparator, the trigger outputs a trigger signal, which is used for subsequent signal processing and analysis.

[0028] The digital-to-analog converter 6 has a resolution of 12 bits and an output voltage of 0 - 5.5 V. Under the control of the FPGA, the output level signal is sent to the comparator for comparison. The output level of the digital-to-analog converter can be adjusted to adapt to time-domain modulation signals with different amplitudes.

[0029] The FPGA 7 has 6272 logic cells, which is responsible for controlling the output level of the digital-to-analog converter, receiving the trigger signal from the trigger, and processing and analyzing the trigger signal. At the same time, the FPGA is also connected to the computer through a serial port to display the current time-domain modulation amount in real time.

[0030] The computer 8 is used to display and analyze the time-domain modulation amount data transmitted by the FPGA.

[0031] Figure 2 Figure 13 is the working flowchart of the detection device for the time-domain modulation signal of the present invention. As shown in the figure, the signal light to be measured first enters a 45 GHz high-speed photodiode. The high-speed photodiode responds to the real-time amplitude of the signal light to be measured and outputs an electrical signal similar to the waveform of the signal light to be measured. The output end of the high-speed photodiode is connected to the input end of the 40 dB low-noise amplifier to amplify the time-domain modulated signal. The output end of the low-noise amplifier is connected to the input end of the 2 - 67 GHz detector. The detector detects the amplified time-domain modulated signal and outputs a detected square-wave signal. The detector is connected to one input end of the comparator, and the output of the comparator is connected to the input end of the trigger.

[0032] Meanwhile, the FPGA controls the digital-to-analog converter to output a level signal to the other end of the comparator. The comparator compares the detected square-wave signal and sends the comparison result signal to the trigger. The output end and the reset end of the trigger are connected to the FPGA. When the trigger is triggered and held, the FPGA resets the trigger to receive the next signal. At the same time, the FPGA is also connected to the computer through a serial port to display the magnitude of the time-domain modulation amount in real time. Thus, the device of the present invention fully realizes the function of detecting and discriminating the time-domain modulation signal.

[0033] In this embodiment, the relationship between the detector voltage and the time-domain modulation degree is detected, and the calculation method of the modulation degree is as follows:

[0034]

[0035] Where Vmax is the maximum value of the high-speed photodiode pulse signal, and Vmin is the minimum value of the high-speed photodiode pulse signal. The present invention realizes the amplification of 18 - 26.5 GHz signals through a low-noise amplifier, and can detect different modulation degrees of signals in different frequency bands by replacing the low-noise amplifier. The optional range of the low-noise amplifier is 2 - 67 GHz of the detector operating frequency. Figure 3 It is the relationship diagram between the detector voltage and the modulation degree obtained by experiments of the present invention. It can be seen that the modulation degree range that can be detected by the present invention is 2 - 10%. Figure 4 It is the result of the online long-term comparative test using the present invention and an oscilloscope, which reflects the long-term stability and reliability of the present invention.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A detection device for miniaturized time-domain modulated signals, characterized in that It includes a high-speed photodiode (1), a low-noise amplifier (2), a detector (3), a comparator (4), a flip-flop (5), a digital-to-analog converter (6), an FPGA (7) and a computer (8); The input end of the high-speed photodiode (1) receives the signal light to be measured, and the output end is connected to the input end of the low-noise amplifier (2). The output end of the low-noise amplifier (2) is connected to the input end of the detector (3), which is used to amplify the electrical signal received from the high-speed photodiode (1). The detector (3) is used to perform detection processing on the amplified electrical signal and output an approximate square-wave signal; One input end of the comparator (4) is connected to the output end of the detector (3), and the other input end is connected to the output end of the digital-to-analog converter (6). It is used to compare the square-wave signal output by the detector (3) and the level signal output by the digital-to-analog converter (6). The output end of the comparator (4) is connected to the input end of the flip-flop (5). The flip-flop (5) receives the comparison result output by the comparator (4) and outputs a trigger signal to the FPGA (7) when the trigger condition is satisfied. The FPGA (7) receives the trigger signal output by the flip-flop (5) and resets the flip-flop (5) when needed. The FPGA (7) is also connected to the computer (8) through a serial port, which is used to transmit the data of the time-domain modulation amount to the computer (8) in real time. The computer (8) receives the time-domain modulation amount data transmitted by the FPGA (7) and performs display and analysis.

2. The detection device for the time-domain modulation signal according to claim 1, characterized in that The response speed of the high-speed photodiode (1) is greater than the modulation frequency of the time-domain modulation.

3. The detection device for the time-domain modulation signal according to claim 1, characterized in that, The gain of the low-noise amplifier (2) is 40 dB.

4. The detection device for the time-domain modulation signal according to claim 1, wherein The flip-flop (5) is designed to be able to meet the requirements of laser short pulses and can capture the short comparison signals output by the comparator (4).

5. The detection device for time-domain modulation signals according to claim 1, characterized in that, The operating frequency range of the detector (3) is 2 - 67 GHz, and the input power range is -25 dBm to 15 dBm.

6. The detection device for the time-domain modulation signal according to claim 1, characterized in that, The propagation delay of the comparator (4) is 150 ps, and the minimum pulse width is 80 ps.

7. The detection device for the time-domain modulation signal according to claim 1, characterized in that, The computer (8) is connected to the FPGA (7) through a serial port and displays and analyzes the time-domain modulation amount data transmitted by the FPGA (7) in real time.

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