Measuring device for half-wave voltage of phase modulator

Abstract

The utility model discloses a measuring device for half-wave voltage of a phase modulator. The measuring device comprises a laser, a signal generator, an interferometer, photoelectric detection equipment and measuring equipment, one arm of the interferometer is provided with a phase modulator to be measured; the signal generator is a pulse signal generator. The utility model discloses a device for measuring the half-wave voltage of a phase modulator, which is characterized in that a pulse modulation electric signal is output by a pulse signal generator to drive a phase modulator to be measured, so that the adverse effect of interference optical signal phase drift on the half-wave voltage measurement can be effectively eliminated, and the accurate measurement of the half-wave voltage is realized. And the optical path is simple in structure and easy to construct, and is widely applied to a QKD system and a quantum measurement and metering system.

Description

TECHNICAL FIELD

[0001] The utility model relates to quantum information and optical communication equipment field, concretely relates to a phase modulator half wave voltage measuring device. BACKGROUND

[0002] Quantum network and quantum computing are becoming more and more popular in various industries. Quantum key distribution (QKD) is a new next-generation secure communication technology that is attracting attention and is actively expanding from point-to-point systems to network architectures. In a QKD network system, the engineering stability of the modulation device is very important.

[0003] A phase modulator is a device that uses the electro-optic effect of a crystal to modulate an optical carrier and has a wide range of practical applications in the field of optical communication. Half-wave voltage refers to the amplitude of the applied electric field that changes the phase of the optical carrier by π, and is an important parameter that describes the working efficiency and energy consumption of the phase modulator.

[0004] In a quantum key distribution system based on phase encoding, the half-wave voltage of the phase modulator directly affects the overall performance of the system, so accurate measurement of the half-wave voltage of the phase modulator is crucial for optimizing the system.

[0005] The existing measuring device places the phase modulator in one arm of a Mach-Zehnder interferometer. According to interference theory, a direct current voltage is applied to the phase modulator, and the phase difference of the light signals in different arms of the interferometer will change with the change in the direct current voltage, resulting in a change in the intensity of the output light signal. Finally, the half-wave voltage is obtained by the difference between the direct current voltages corresponding to the adjacent maximum or minimum values of the output light signal intensity. However, in the existing measuring device, the phase of the interference light signal is easily affected by changes in the external environment and drifts, making it difficult to maintain the stability of the signal intensity output by the interferometer, and thus accurate measurement of the half-wave voltage is difficult to achieve. SUMMARY

[0006] The utility model discloses a phase modulator half wave voltage measuring device to solve the problem that the existing measuring device is difficult to achieve accurate measurement of the half-wave voltage.

[0007] To achieve the above object, the technical scheme adopted by the utility model is as follows:

[0008] A phase modulator half-wave voltage measuring device includes a laser, a signal generator, an interferometer, a photoelectric detection device, and a measuring device. One arm of the interferometer is provided with a phase modulator to be measured.

[0009] The signal generator is a pulse signal generator.

[0010] The output end of the laser is connected with the input end of the interferometer, the output end of the signal generator is connected with the input end of the phase modulator to be measured, the output end of the interferometer is connected with the input end of the photoelectric detection device, and the output end of the photoelectric detection device is connected with the input end of the measuring device.

[0011] In the scheme, the pulse modulated electrical signal output by the pulse signal generator is used to drive the phase modulator to be measured, so that the adverse effect of phase drift of the interference optical signal on the measurement of the half-wave voltage can be effectively eliminated, and accurate measurement of the half-wave voltage is realized.

[0012] Preferably, the laser is a continuous laser.

[0013] Preferably, the laser is a pulse laser.

[0014] Preferably, the working frequency of the pulse laser is an integer multiple of the working frequency of the signal generator.

[0015] Preferably, the working frequency of the pulse laser is twice the working frequency of the signal generator.

[0016] Preferably, the duty cycle of the signal generator is 50%.

[0017] Preferably, the interferometer comprises a beam splitter and a beam combiner.

[0018] The output end of the laser is connected with the input end of the beam splitter, the first output end of the beam splitter is connected with the first input end of the beam combiner through the phase modulator to be measured, the second output end of the beam splitter is connected with the second input end of the beam combiner, and the output end of the beam combiner is connected with the input end of the photoelectric detection device.

[0019] Preferably, the two arms of the interferometer are equal in length.

[0020] Preferably, the photoelectric detection device is a photon detector.

[0021] Preferably, the measuring device is an oscilloscope.

[0022] The beneficial technical effects of the utility model are as follows:

[0023] The utility model provides a kind of measurement device of phase modulator half-wave voltage, and the pulse modulated electrical signal output by pulse signal generator is used to drive the phase modulator to be measured, so that the adverse effect of phase drift of the interference optical signal on the measurement of the half-wave voltage can be effectively eliminated, and accurate measurement of the half-wave voltage is realized. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is the module connection schematic view of one embodiment of the utility model.

[0025] Figure 2 The module connection schematic view of another embodiment of the utility model;

[0026] Wherein: 11, continuous laser; 12, pulse laser; 2, signal generator; 3, interferometer; 31, beam splitter; 32, beam combiner; 4, photoelectric detection equipment; 5, measuring equipment; 6, phase modulator to be measured. DETAILED DESCRIPTION

[0027] In order to make the utility model's purpose, technical scheme and advantage more clearly, the following with example to the utility model carries out further detailed explanation, but the utility model's scope of protection is not limited to the following specific embodiment.

[0028] Example 1

[0029] As Figure 1 The phase modulator half-wave voltage measuring device shown in a kind of, including laser, signal generator 2, interferometer 3, photoelectric detection equipment 4 and measuring equipment 5;One arm of the interferometer 3 is equipped with phase modulator 6 to be measured;

[0030] The signal generator 2 is pulse signal generator;

[0031] The output end of the laser is connected with the input end of interferometer 3, the output end of signal generator 2 is connected with the input end of phase modulator 6 to be measured, the output end of interferometer 3 is connected with the input end of photoelectric detection equipment 4, the output end of photoelectric detection equipment 4 is connected with the input end of measuring equipment 5.

[0032] In the specific implementation process, the pulse modulated electric signal is output by pulse signal generator to drive phase modulator 6 to be measured, can effectively eliminate the adverse effects of interference light signal phase drift on half-wave voltage measurement, to realize the accurate measurement of half-wave voltage;And optical path structure is simple, easy to build.

[0033] Example 2

[0034] The phase modulator half-wave voltage measuring device shown in a kind of, including laser, signal generator 2, interferometer 3, photoelectric detection equipment 4 and measuring equipment 5;One arm of the interferometer 3 is equipped with phase modulator 6 to be measured;

[0035] The signal generator 2 is pulse signal generator;

[0036] The output end of the laser is connected with the input end of interferometer 3, the output end of signal generator 2 is connected with the input end of phase modulator 6 to be measured, the output end of interferometer 3 is connected with the input end of photoelectric detection equipment 4, the output end of photoelectric detection equipment 4 is connected with the input end of measuring equipment 5.

[0037] More specifically, the laser is a continuous laser 11.

[0038] More specifically, the interferometer 3 comprises a beam splitter 31 and a beam combiner 32.

[0039] The output end of the laser is connected with the input end of the beam splitter 31, the first output end of the beam splitter 31 is connected with the first input end of the beam combiner 32 through the phase modulator 6 to be measured, the second output end of the beam splitter 31 is connected with the second input end of the beam combiner 32, and the output end of the beam combiner 32 is connected with the input end of the photoelectric detection device 4.

[0040] More specifically, the two arms of the interferometer 3 are equal in length.

[0041] More specifically, the photoelectric detection device 4 is a photon detector.

[0042] More specifically, the measuring device 5 is an oscilloscope.

[0043] In the specific implementation process, the continuous laser 11 generates a continuous light signal, which is divided into a first light signal and a second light signal after inputting the beam splitter 31, wherein the first light signal is input into the phase modulator 6 to be measured, and the second light signal is directly input into the beam combiner 32.

[0044] The signal generator 2 generates a pulse modulation electric signal to drive the phase modulator 6 to be measured to modulate the phase of the first light signal, and the phase modulation signal is input into the beam combiner 32 to interfere with the second light signal, and the light signal output by the interference is input into the photon detector for photoelectric conversion to obtain the measured electric signal.

[0045] The phase of the first light signal depends on the amplitude of the pulse modulation electric signal, and the phase difference between the first light signal and the second light signal will change with the waveform of the pulse modulation electric signal. Therefore, considering the rise and fall times of the pulse modulation electric signal and the influence of external environmental factors, in general cases, a waveform with a single peak and a single valley in a period will be observed in the oscilloscope, and the single peak duration is equal to the high level duration of the pulse modulation electric signal, and the single valley duration is equal to the low level duration of the pulse modulation electric signal, or the single peak duration is equal to the low level duration of the pulse modulation electric signal, and the single valley duration is equal to the high level duration of the pulse modulation electric signal, or a waveform with double peaks and double valleys in a period, and the double peak durations are equal to the high level and low level durations of the pulse modulation electric signal respectively, and the double valley durations are equal to the rise and fall times of the pulse modulation electric signal respectively, but the double peak values are not equal.

[0046] Only when the phase difference between the two components of the continuous light signal is 2kπ (k=0, 1, 2, 3…), i.e. the amplitude of the pulse modulation electric signal is half the wave voltage Vπ When the number of the pulse modulation signal is an even multiple of the number of the signal generator, the oscilloscope continuously displays the waveform with double peaks and double valleys in a period, the peak values of the double peaks are equal, the durations of the double peaks are equal to the durations of the high level and low level of the pulse modulation signal respectively, and the durations of the double valleys are equal to the rise time and fall time of the pulse modulation signal respectively, otherwise, the waveform displayed by the oscilloscope changes continuously with the fluctuation of the external environment.

[0047] Embodiment 3

[0048] As Figure 2 Therefore, the embodiment provides a device for measuring the half-wave voltage of a phase modulator, which is basically the same as the device for measuring the half-wave voltage of a phase modulator in Embodiment 2, and the difference lies in that the type of the laser is different.

[0049] More specifically, the laser is a pulse laser 12.

[0050] More specifically, the working frequency of the pulse laser 12 is an integer multiple of the working frequency of the signal generator 2.

[0051] In the specific implementation process, the pulse laser 12 is connected with the signal generator 2 to ensure that the working frequency of the pulse laser 12 is an integer multiple of the working frequency of the signal generator 2.

[0052] More specifically, the working frequency of the pulse laser 12 is twice the working frequency of the signal generator 2.

[0053] More specifically, the duty cycle of the signal generator 2 is 50%.

[0054] In the specific implementation process, the pulse laser 12 generates a pulse optical signal, and the pulse optical signal is divided into a first optical signal and a second optical signal after being input into the beam splitter 31, wherein the first optical signal is input into the phase modulator 6 to be measured, and the second optical signal is directly input into the beam combiner 32.

[0055] The signal generator 2 generates a pulse modulation signal to drive the phase modulator 6 to be measured to modulate the phase of the first optical signal, and the phase modulation signal is input into the beam combiner 32 to interfere with the second optical signal, and the interference output optical signal is input into the photonic detector for photoelectric conversion to obtain the measured electrical signal.

[0056] Wherein, the delay of the pulse modulation signal is set to make the adjacent waveform amplitudes of the measured electrical signal displayed in the oscilloscope have the maximum difference.

[0057] Because only when the difference between the phase differences of the two components of the adjacent pulse optical signals is That is, the amplitude of the pulse modulation signal is the half-wave voltage V πWhen the number of the adjacent waveforms displayed in the oscilloscope is an even number, the amplitudes of the adjacent waveforms displayed in the oscilloscope are equal, otherwise, the amplitude difference of the adjacent waveforms displayed in the oscilloscope fluctuates with the external environment.

[0058] According to the disclosure and teaching of the above description, the skilled in the art of the present application can also change and modify the above embodiments. Therefore, the present application is not limited to the specific embodiments disclosed and described above, and some modifications and changes of the present application should fall within the protection scope of the claims of the present application. In addition, although some specific terms are used in the specification, these terms are only for convenience and do not constitute any limitation on the present application.

Claims

1. A device for measuring the half-wave voltage of a phase modulator, characterized in that, The apparatus comprises a laser, a signal generator, an interferometer, a photoelectric detection device and a measuring device; one arm of the interferometer is provided with a phase modulator to be measured; The signal generator is a pulse signal generator; The output end of the laser is connected with the input end of the interferometer, the output end of the signal generator is connected with the input end of the phase modulator to be measured, the output end of the interferometer is connected with the input end of the photoelectric detection device, and the output end of the photoelectric detection device is connected with the input end of the measuring device.

2. A device for measuring the half-wave voltage of a phase modulator according to claim 1, characterized in that The laser is a continuous laser.

3. A device for measuring the half-wave voltage of a phase modulator according to claim 1, characterized in that The laser is a pulse laser.

4. A device for measuring the half-wave voltage of a phase modulator according to claim 3, characterized in that The working frequency of the pulse laser is an integer multiple of the working frequency of the signal generator.

5. A device for measuring the half-wave voltage of a phase modulator according to claim 4, characterized in that The working frequency of the pulse laser is twice the working frequency of the signal generator.

6. A device for measuring the half-wave voltage of a phase modulator according to claim 1, characterized in that The duty cycle of the signal generator is 50%.

7. A device for measuring the half-wave voltage of a phase modulator according to claim 1, characterized in that The interferometer comprises a beam splitter and a beam combiner; The output end of the laser is connected with the input end of the beam splitter, the first output end of the beam splitter is connected with the first input end of the beam combiner through the phase modulator to be measured, the second output end of the beam splitter is connected with the second input end of the beam combiner, and the output end of the beam combiner is connected with the input end of the photoelectric detection device.

8. A device for measuring the half-wave voltage of a phase modulator according to claim 1 or 7, characterized in that The two arms of the interferometer are equal in length.

9. A device for measuring the half-wave voltage of a phase modulator according to claim 1, characterized in that The photoelectric detection device is a photon detector.

10. The apparatus of claim 1, wherein, The measuring device is an oscilloscope.

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