Multi-soliton time domain distribution characterization device and method

Abstract

The invention belongs to the technical field of quantum information science, and particularly relates to a multi-soliton time domain distribution representation device and method. According to the multi-soliton time domain distribution characterization method, the time delay of one arm of the HOM interferometer is changed through the adjustable light delay line to carry out coincidence measurement of HOM interference, and characterization of multi-soliton time domain features is achieved. All devices used in the stability test method are mature commercial devices, can be used in the fields of quantum communication, quantum calculation, quantum precision measurement and the like, and are beneficial to practical and commercialized development of light quantum information science and technology.

Description

Technical Field

[0001] The present invention belongs to the field of quantum information science and technology, and specifically relates to a multi-soliton time-domain distribution characterization device and method. Background Art

[0002] Microcavity optical frequency comb technology exhibits a wealth of physical phenomena in the field of optics. However, the in-depth study and application of these phenomena rely on effective testing methods for precise characterization and analysis. Currently, the characterization of microcavity optical frequency combs is mainly divided into three categories: spectral characterization, time-domain waveform characterization, and radio frequency spectrum characterization. Spectral characterization can intuitively reflect the intensity distribution of the microcavity optical frequency comb at different frequencies or wavelengths; time-domain waveform characterization can directly display the number of solitons in the Kerr optical frequency comb and the evolution process between soliton states by observing the waveform of the optical frequency comb changing with time, helping to reveal the dynamic change law of the optical frequency comb; radio frequency spectrum characterization can reveal the influence of various noise sources such as thermal noise, phase noise, and mechanical noise by analyzing the intensity spectrum obtained by the beat frequency of the microcavity optical frequency comb. These characterization methods are crucial to promoting the research and application of microcavity optical frequency combs.

[0003] In recent years, with the development of quantum optics, the use of quantum interference measurement methods at the single-photon energy level to characterize the properties of light sources has gradually matured. For example, existing research has used HOM interferometry to achieve pulse width measurement of passively mode-locked light sources, avoiding the influence of the light amplification process when measuring pulse width using an autocorrelator, as well as the influence of dispersion when using direct photodetection. HOM interferometry can accurately measure the temporal distribution of multiple solitons in microcavity optical frequency combs. Its advantage lies in the high sensitivity of single-photon detectors, which can clearly capture the time domain characteristics of multiple solitons in microcavity optical frequency combs, which is difficult to achieve with traditional photodetection equipment. This measurement method provides a novel and efficient technical means for the fine time domain characterization of microcavity optical frequency combs, which will help promote the further research and application of microcavity optical frequency combs. Summary of the Invention

[0004] To address the problems of the existing technology, the present invention provides a device and method for characterizing the time-domain distribution of multiple solitons. The present invention provides a method for characterizing the time-domain distribution of multiple solitons. By using an adjustable optical delay line to change the delay of one arm of a HOM interferometer, the HOM interferometer (HOM) interferometer is measured to achieve coincidence, ultimately characterizing the time-domain characteristics of multiple solitons.

[0005] The technical solution of the present invention is:

[0006] A multi-soliton time-domain distribution characterization device includes a soliton light source 1, a first beam splitter 2, a first adjustable optical attenuator 3, a second adjustable optical attenuator 4, a first polarization controller 5, a second polarization controller 6, an adjustable optical delay line 7, a first polarization beam splitter 8, a second polarization beam splitter 9, a second beam splitter 10, a third polarization controller 11, a fourth polarization controller 12, a first single-photon detector 13, a second single-photon detector 14, a time-to-digital converter 15, and a data processing device 16;

[0007] The output end of the soliton light source 1 is connected to the input end of the first beam splitter 2; the two output ends of the first beam splitter 2 are respectively connected to the input end of the first adjustable optical attenuator 3 and the input end of the second adjustable optical attenuator 4; the first adjustable optical attenuator 3, the first polarization controller 5 and the first polarization beam splitter 8 are connected in sequence; the second adjustable optical attenuator 4, the second polarization controller 6, the adjustable optical delay line 7 and the second polarization beam splitter 9 are connected in sequence; the output end of the first polarization beam splitter 8 and the output end of the second polarization beam splitter 9 are connected to the input end of the second beam splitter 10; the output end of the second beam splitter 10 is respectively connected to the input end of the third polarization controller 11 and the input end of the fourth polarization controller 12; the output end of the third polarization controller 11 is connected to the input end of the first single-photon detector 13; the output end of the fourth polarization controller 12 is connected to the input end of the second single-photon detector; the output end of the first single-photon detector 13 and the output end of the second single-photon detector 14 are connected to the input end of the time-to-digital converter 15; the output end of the time-to-digital converter 15 is connected to the input end of the data processing device 16;

[0008] The first adjustable optical attenuator 3, the first polarization controller 5 and the first polarization beam splitter 8 connected in sequence constitute the first arm of the HOM interferometer, and the second adjustable optical attenuator 4, the second polarization controller 6, the adjustable optical delay line 7 and the second polarization beam splitter 9 connected in sequence constitute the second arm of the HOM interferometer; the soliton light source 1 is used to provide a dual soliton light source with high stability, and the first beam splitter 2 divides the light output by the soliton light source 1 into two parts, which are respectively incident on the first arm and the second arm of the HOM interferometer symmetrically; the first adjustable optical attenuator 3 and the second adjustable optical attenuator 4 are used to attenuate the received light to the single-photon level; the first polarization controller 5 and the second polarization controller 6 are used to adjust the polarization states of the two arms of the interferometer so that the polarization states of the two arms remain consistent; the adjustable optical delay line 7 is used to adjust the delay of the incident light; the first polarization beam splitter 8 and the second polarization beam splitter 9 are used to adjust the polarization state of the photon so that the polarization states of the photons in the two arms are the same; the time-to-digital converter 15 is used to record the electrical signals output by the first single-photon detector 13 and the second single-photon detector 14, and transmit the measurement results to the data processing device 16, which analyzes the data to obtain the time domain characteristics of the multi-soliton.

[0009] Furthermore, the soliton light source 1 is a mode-locked laser source, which generates optical solitons by electro-optical modulation or micro-ring / micro-disk / glass rod cavity micro-nano devices.

[0010] Furthermore, the first adjustable optical attenuator 3 and the second adjustable optical attenuator 4 are digital optical attenuators or mechanical optical attenuators.

[0011] Furthermore, the first polarization controller 5 , the second polarization controller 6 , the third polarization controller 11 and the fourth polarization controller 12 are manual optical fiber polarization controllers or electric optical fiber polarization controllers.

[0012] Furthermore, the dimmable delay line 7 is a manual delay line or an electric delay line.

[0013] Furthermore, the first single-photon detector 13 and the second single-photon detector 14 are avalanche diode single-photon detectors or superconducting nanowire single-photon detectors; the first beam splitter 2 and the second beam splitter 10 are 50 / 50 beam splitters.

[0014] Furthermore, the first polarization beam splitter 8 and the second polarization beam splitter 9 are one of a flat plate polarization beam splitter, a cube polarization beam splitter or a fiber polarization beam splitter.

[0015] A method for characterizing multi-soliton time-domain distribution, comprising:

[0016] A soliton light source 1 is used to emit solitons, and the output light beam is split into two parts by a first beam splitter 2. The two parts are incident on the first and second symmetrical arms of the HOM interferometer respectively. The optical output power of the first arm is adjusted to the single-photon level by a first adjustable optical attenuator 3; the optical output power of the second arm is adjusted to be consistent with the single-photon level of the first arm by a second adjustable optical attenuator 4. The polarization states of the photons in the two arms are made consistent by a first polarization controller 5 and a second polarization controller 6. The time delay of the incident light is adjusted by an adjustable optical delay line 7. The polarization states of the photons in the two arms are made consistent by a first polarization beam splitter 8 and a second polarization beam splitter 9.

[0017] The two-arm photons are input into the second beam splitter 10 for HOM interference; the first single-photon detector 13 and the second single-photon detector 14 convert the detected optical signal into an electrical signal, and the output electrical signal arrives at the time digital converter 15 for coincidence counting measurement, and the measurement results are transmitted to the data processing equipment 16 for data processing to obtain the time domain distribution characteristics of multiple solitons.

[0018] The present invention provides a method for characterizing the time-domain distribution of multiple solitons. This method utilizes an adjustable optical delay line to vary the delay of one arm of a HOM interferometer to perform coincidence measurement of HOM interference, thereby characterizing the time-domain characteristics of multiple solitons. All components used in this stable testing method are mature, commercially available devices and can be used in fields such as quantum communication, quantum computing, and quantum precision measurement, facilitating the practical and commercial development of optical quantum information technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the structure of a method for characterizing the time-domain distribution of double solitons according to an embodiment of the present invention;

[0020] Figure 2 This is a double soliton frequency comb spectrum diagram according to an embodiment of the present invention;

[0021] Figure 3 This is the time domain distribution result of the double soliton in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The principles and features of the present invention are described below with reference to the accompanying drawings and embodiments.

[0023] Example

[0024] The device comprises a soliton light source 1, a first beam splitter 2, a first adjustable optical attenuator 3, a second adjustable optical attenuator 4, a first polarization controller 5, a second polarization controller 6, an adjustable optical delay line 7, a first polarization beam splitter 8, a second polarization beam splitter 9, a second beam splitter 10, a third polarization controller 11, a fourth polarization controller 12, a first single-photon detector 13, a second single-photon detector 14, a time-to-digital converter 15, and a data processing device 16;

[0025] The soliton light source 1 and the first beam splitter 2 are connected in sequence; the two output ends of the first beam splitter 2 are connected to the first adjustable optical attenuator 3 and the second adjustable optical attenuator 4 respectively; the first adjustable optical attenuator 3, the first polarization controller 5 and the first polarization beam splitter 8 are connected in sequence; the second adjustable optical attenuator 4, the second polarization controller 6, the adjustable optical delay line 7 and the second polarization beam splitter 9 are connected in sequence; the first polarization beam splitter 8 and the second polarization beam splitter 9 are connected to the input end of the second beam splitter 10 respectively; the output end of the second beam splitter 10 is connected to the third polarization controller 11 and the fourth polarization controller 12 respectively; the third polarization controller 11 and the first single-photon detector 13 are connected in sequence; the fourth polarization controller 12 and the second single-photon detector are connected in sequence; the output ends of the first single-photon detector 13 and the second single-photon detector 14 are connected to the time-to-digital converter 15; the time-to-digital converter 15 and the data processing equipment 16 are connected in sequence.

[0026] The first beam splitter 2 splits the double solitons output by the soliton light source 1 into two parts, which are respectively incident on the first arm and the second arm of the HOM interferometer, wherein the first arm includes a first adjustable optical attenuator 3, a first polarization controller 5 and a first polarization beam splitter 8 connected in sequence, and the second arm includes a second adjustable optical attenuator 4, a second polarization controller 6, an adjustable optical delay line 7 and a second polarization beam splitter 9 connected in sequence;

[0027] The first adjustable optical attenuator 3 and the second adjustable optical attenuator 4 are used to attenuate the soliton light source 1 to a single photon level;

[0028] The first polarization controller 5, the second polarization controller 6, the third polarization controller 11 and the fourth polarization controller 12 are used to adjust the polarization states of the two arms of the interferometer so that the polarization states of the two arms remain consistent;

[0029] The adjustable delay line 7 is used to adjust the delay of the incident light;

[0030] The first polarization beam splitter 8 and the second polarization beam splitter 9 are used to adjust the polarization state of the photons so that the polarization states of the photons in the two arms are the same;

[0031] The time-to-digital converter 15 is used to record the time sequence of the electrical signals output by the first single-photon detector 13 and the second single-photon detector 14 arriving at the time-to-digital converter 15 , and the time sequence is transmitted to the data processing device 16 in digital form.

[0032] The data processing device 16 performs data processing to obtain the time domain characteristics of the multi-soliton.

[0033] In the above embodiment, HOM interferometer coincidence measurement is performed by varying the delay of one arm of the HOM interferometer using an adjustable optical delay line, enabling characterization of the multi-soliton time-domain distribution. This stability test method utilizes mature, commercially available components with applications in quantum communication, quantum computing, and quantum precision measurement, facilitating the practical and commercial development of optical quantum information technology.

[0034] The soliton light source 1 is used to provide a dual soliton light source with high stability. The soliton light source is generated by using an auxiliary laser to balance the thermal response in the silicon nitride microring resonator. Figure 2 Shown is the spectrum of a double soliton.

[0035] The first beam splitter 2 is a C-band beam splitter with a return loss greater than 50 dB and has one input port and two output ports. The input port of the first beam splitter 2 is connected to the mode-locked laser, and the two output ports are connected to the first adjustable optical attenuator 3 and the second adjustable optical attenuator, respectively. The output end splitting ratio is 50:50.

[0036] The first and second adjustable optical attenuators 3 and 4 precisely control the laser's output power by adjusting knobs, adjusting the optical output power to the single-photon level. This embodiment uses a mechanical optical attenuator with a tunable center wavelength of 1550 nm, a maximum attenuation of 60 dB, and an insertion loss of 1.2 dB.

[0037] The first polarization controller 5, the second polarization controller 6, the third polarization controller 11, and the fourth polarization controller 12 are used to control the polarization consistency of the two arms of the HOM interferometer, meeting the HOM interference effect's requirement for the polarization degree of freedom to be completely homogeneous. This embodiment uses FPC561, with a wavelength range of 1260-1625 nm and an insertion loss of 0.1 dB.

[0038] The adjustable optical delay line 7 is used to adjust the delay of the incident light, achieving micron-level precision in changing the interferometer arm path difference. This embodiment uses the General Photonics motorized adjustable optical delay line MDL002, which has a delay range of 0-560 ps, ​​a resolution of 1 fs, and a return loss greater than 50 dB. The actual adjustment range in this embodiment is -1 ps to +15 ps relative to the delay zero point.

[0039] The second beam splitter 10 is used to realize HOM interference. The identical photons generated by the two arms of the interferometer are respectively incident from the two input ports of the polarization beam splitter. When the difference in length between the two arms is greater than the coherence length of the light beam, the two photons are output from the two output ports of the second beam splitter 10 with the same probability. When the two identical photons arrive at the second beam splitter 10 at the same time, the two photons are indistinguishable. Due to the photon bunching effect, both photons are emitted from one output port of the second beam splitter 10, and there will not be a situation where there is one photon at each port. This embodiment uses a four-port coupler with a polarization-maintaining pigtail. The working mode is slow-axis alignment. It has two input ports and two output ports. The output end splitting ratio is 50:50. The two input ports are respectively connected to the two arms of the HOM interferometer, and the two output ports are respectively connected to the first single-photon detector 13 and the second single-photon detector 14.

[0040] The first and second single-photon detectors 13 and 14 are used to detect photons from the two optical paths after HOM interference, converting the optical signals into electrical signals for input into a time-to-digital converter. This embodiment uses superconducting nanowire single-photon detectors, achieving a detection efficiency of 75% for light in the 1550 nm band, a dark count rate of less than 100 Hz, and a time jitter of 68 ps.

[0041] The time-to-digital converter 15 is used to record the number of incident photons in two independent channels of the single-photon detector, record their accurate time signals and channel numbers, and transmit the data to the computer, which then obtains the coincidence count rate. After data processing, the time domain distribution of the double solitons and the time width between each interference peak can be obtained, such as Figure 3 This embodiment uses a Qutag time-to-digital converter, with a fast counting rate of up to 100 Mcps per channel and a resolution of 1 ps.

[0042] Optionally, the soliton light source 1 may be a mode-locked laser source, an optical soliton generated by electro-optical modulation or a micro-nano device such as a micro-ring / micro-disk / glass rod cavity, etc.;

[0043] Optionally, the first adjustable optical attenuator 3 and the second adjustable optical attenuator 4 are digital optical attenuators or mechanical optical attenuators;

[0044] Optionally, the first polarization controller 5 , the second polarization controller 6 , the third polarization controller 11 and the fourth polarization controller 12 may include any one of a manual fiber polarization controller and an electric fiber polarization controller;

[0045] Optionally, the dimmable delay line 7 is a manual delay line or an electric delay line;

[0046] Optionally, the first polarization beam splitter 8 and the second polarization beam splitter 9 may include any one of a flat plate polarization beam splitter, a cube polarization beam splitter, and a fiber polarization beam splitter;

[0047] Optionally, the first single-photon detector 13 and the second single-photon detector 14 are avalanche diode single-photon detectors or superconducting nanowire single-photon detectors;

[0048] And / or, the first beam splitter 2 and the second beam splitter 10 are 50 / 50 beam splitters.

[0049] The dual-soliton time-domain distribution characterization method provided in an embodiment of the present invention is based on the aforementioned multi-soliton time-domain distribution characterization implementation, and includes the following steps:

[0050] A soliton light source 1 emits dual solitons, and the output beam is split into two parts by a first beam splitter 2. The two parts are incident on the symmetrical first and second arms of the HOM interferometer, respectively. The optical output power of the first arm is adjusted to the single-photon level by an adjustable optical attenuator 3. The optical output power of the second arm is adjusted to the single-photon level by an adjustable optical attenuator 4. The polarization states of the photons in the two arms are aligned by first and second polarization controllers 5 and 6, and the delay of the incident light is adjusted by an adjustable optical delay line 7. The polarization states of the photons in the two arms are aligned by first and second polarization beam splitters 8 and 9. The photons in the two arms are then input into a second beam splitter 10 for second-order HOM interference. The polarization states of the photons in the two arms are aligned by third and fourth polarization controllers 11 and 12. First and second single-photon detectors 13 and 14 convert the detected optical signals into electrical signals. The time series of the output electrical signals arrives at a time-to-digital converter 15, and coincidence measurement is performed on a data processing device 16. By setting different delay positions of the adjustable delay line 7 and recording the single photon counting rate changes and time domain distribution results of the first single photon detector 13 and the second single photon detector 14 during the test, the time domain state and evolution process of the multi-soliton under different delay conditions are obtained. Figure 3 The figure shows the time domain characteristics of the double solitons, where the period of the double solitons is about 10.1±0.3 ps, the corresponding free spectrum range of the microring resonator is 100 GHz, and the time interval between the double solitons is about 4.31±0.04 ps.

[0051] Figure 2 Shown is the spectrum of a double soliton. Figure 2 The horizontal axis is the wavelength and the vertical axis is the soliton power.

[0052] Figure 3 Shown is the time domain distribution of double solitons. Figure 3 The horizontal axis in the middle is the relative delay difference. The relative delay difference of the point with the minimum count is defined as 0. The relative delay difference of the remaining points is the difference between the delay line delay of the point and the delay line delay of the point with the minimum count.

[0053] The multi-soliton time-domain distribution characterization method disclosed in the present invention can be used in fields such as quantum communication, quantum computing, and quantum precision measurement, and is conducive to the practical and commercial development of optical quantum information technology.

Claims

1. A multi-soliton time-domain distribution characterization device, comprising a soliton light source (1), a first beam splitter (2), a first adjustable optical attenuator (3), a second adjustable optical attenuator (4), a first polarization controller (5), a second polarization controller (6), an adjustable optical delay line (7), a first polarization beam splitter (8), a second polarization beam splitter (9), a second beam splitter (10), a third polarization controller (11), a fourth polarization controller (12), a first single-photon detector (13), a second single-photon detector (14), a time-to-digital converter (15), and a data processing device (16); The output end of the soliton light source (1) is connected to the input end of the first beam splitter (2); the two output ends of the first beam splitter (2) are respectively connected to the input end of the first adjustable optical attenuator (3) and the input end of the second adjustable optical attenuator (4); the first adjustable optical attenuator (3), the first polarization controller (5) and the first polarization beam splitter (8) are connected in sequence; the second adjustable optical attenuator (4), the second polarization controller (6), the adjustable optical delay line (7) and the second polarization beam splitter (9) are connected in sequence; the output end of the first polarization beam splitter (8) and the output end of the second polarization beam splitter (9) are connected to the second beam splitter (10 ); the output end of the second beam splitter (10) is connected to the input end of the third polarization controller (11) and the input end of the fourth polarization controller (12); the output end of the third polarization controller (11) is connected to the input end of the first single-photon detector (13); the output end of the fourth polarization controller (12) is connected to the input end of the second single-photon detector; the output end of the first single-photon detector (13) and the output end of the second single-photon detector (14) are connected to the input end of the time-to-digital converter (15); the output end of the time-to-digital converter (15) is connected to the input end of the data processing device (16); The first adjustable optical attenuator (3), the first polarization controller (5) and the first polarization beam splitter (8) connected in sequence constitute the first arm of the HOM interferometer, and the second adjustable optical attenuator (4), the second polarization controller (6), the adjustable optical delay line (7) and the second polarization beam splitter (9) connected in sequence constitute the second arm of the HOM interferometer; the soliton light source (1) is used to provide a dual soliton light source with high stability, and the first beam splitter (2) divides the light output by the soliton light source (1) into two parts, which are respectively incident on the first arm and the second arm of the HOM interferometer; the first adjustable optical attenuator (3) and the second adjustable optical attenuator (4) are used to receive the light The first polarization controller (5) and the second polarization controller (6) are used to adjust the polarization states of the two arms of the interferometer so that the polarization states of the two arms are consistent; the adjustable optical delay line (7) is used to adjust the time delay of the incident light; the first polarization beam splitter (8) and the second polarization beam splitter (9) are used to adjust the polarization state of the photons so that the polarization states of the photons in the two arms are the same; the time-to-digital converter (15) is used to record the electrical signals output by the first single-photon detector (13) and the second single-photon detector (14), and transmit the measurement results to the data processing device (16), and the data processing device (16) analyzes the data to obtain the time domain characteristics of the multi-soliton.

2. The multi-soliton time domain distribution characterization device according to claim 1, characterized in that: The soliton light source (1) is a mode-locked laser source, and optical solitons are generated by electro-optical modulation or micro-ring / micro-disk / glass rod cavity micro-nano devices.

3. The multi-soliton time domain distribution characterization device according to claim 1, characterized in that: The first adjustable optical attenuator (3) and the second adjustable optical attenuator (4) are digital optical attenuators or mechanical optical attenuators.

4. The multi-soliton time domain distribution characterization device according to claim 1, characterized in that: The first polarization controller (5), the second polarization controller (6), the third polarization controller (11) and the fourth polarization controller (12) are manual optical fiber polarization controllers or electric optical fiber polarization controllers.

5. The multi-soliton time domain distribution characterization device according to claim 1, characterized in that: The adjustable light delay line (7) is a manual delay line or an electric delay line.

6. The method for characterizing the time domain distribution of multiple solitons according to claim 1, characterized in that: The first single-photon detector (13) and the second single-photon detector (14) are avalanche diode single-photon detectors or superconducting nanowire single-photon detectors; the first beam splitter (2) and the second beam splitter (10) are 50 / 50 beam splitters.

7. The multi-soliton time domain distribution characterization device according to claim 1, characterized in that: The first polarization beam splitter (8) and the second polarization beam splitter (9) are one of a flat plate polarization beam splitter, a cube polarization beam splitter or a fiber polarization beam splitter.

8. A method for characterizing a multi-soliton time domain distribution according to any one of claims 1 to 7, characterized in that: include: A soliton light source (1) is used to emit solitons, and the output light beam is divided into two parts by a first beam splitter (2), which are respectively incident on a first arm and a second arm of a symmetrical HOM interferometer. The light output power of the first arm is adjusted to a single-photon level by a first adjustable optical attenuator (3); the light output power of the second arm is adjusted to be consistent with the single-photon level of the first arm by a second adjustable optical attenuator (4), and the polarization states of the photons in the two arms are made consistent by a first polarization controller (5) and a second polarization controller (6); the time delay of the incident light is adjusted by an adjustable optical delay line (7); and the polarization states of the photons in the two arms are made consistent by a first polarization beam splitter (8) and a second polarization beam splitter (9); The photons of the two arms are input to the second beam splitter (10) for HOM interference; the first single-photon detector (13) and the second single-photon detector (14) convert the detected optical signals into electrical signals, the output electrical signals arrive at a time-to-digital converter (15) for coincidence counting measurement, and the measurement results are transmitted to a data processing device (16) for data processing to obtain the time-domain distribution characteristics of the multi-soliton.

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