CN118050739B - A quantum safety laser radar device and ranging method based on thermal light source - Google Patents

Abstract

The invention discloses a quantum safety laser radar device based on a thermal light source and a distance measuring method, and belongs to the field of laser radars. The device comprises a thermal light source; a narrow band filter; the unbalanced beam splitting module is used for splitting the filtered thermal state optical signals to generate a first thermal state optical signal and a second thermal state optical signal with different intensities; a telescope for irradiating the target after expanding the beam of the second thermal state optical signal; a polarization processing module; a circulator; a local oscillator laser; a first beam splitter; a first conjugate homodyne detection module; and a second conjugate homodyne detection module. The device directly utilizes the randomness of the regular component of the light source, does not need to use a random number generator to generate random numbers, omits a modulation device and a corresponding driving circuit, reduces the complexity of a system, and is easier to miniaturize and chip; the device is used for ranging, and the influence of limited modulation precision and modulation errors on the detection deception jamming capability is eliminated.

Description

A quantum safety laser radar device and ranging method based on thermal light source

Technical Field

The present invention belongs to the field of laser radar, and in particular relates to a quantum safety laser radar device and a ranging method based on a thermal light source.

Background technique

Conventional lidar uses classical light signals. By intercepting and retransmitting the signals, the complete information of the lidar signal can be obtained, thereby achieving deceptive interference to the lidar.

Applying quantum technology to the radar field, using the characteristics of entangled quantum states, non-cloning of single-photon quantum states, and measurement collapse to detect deception interference, can effectively identify interception and retransmission attacks and improve the security and reliability of detection. For example, the literature M. Malik, et al. Secure quantum LIDAR, Frontiers in Optics. OpticaPublishing Group, 2012: FM3C. 3 and Wang Q, et al. Pseudorandom modulationquantum secured lidar. Optik, 2015, 126(22): 3344-3348 uses polarization-encoded attenuated laser as the quantum state of the target. If the target intercepts, measures and retransmits the quantum state in an attempt to deceitfully interfere, it will cause a high bit error rate at the receiving end and thus be discovered. However, this type of solution requires the use of extremely weak light (such as a single pulse with an average photon number of 0.1) as the detection signal, and the large transmission loss and scattering in free space will seriously limit its effective range. In addition, this type of solution requires the use of wave plates or electro-optic modulators to modulate the random polarization state, which requires complex drive circuits for control. This not only makes the system more complex, but also the polarization state will be affected by atmospheric disturbances and target scattering, resulting in a high false alarm rate and low practicality. The Chinese patent application (publication number CN116381643A) proposes a coherent state based on Gaussian modulation for target detection, which can detect whether the target has deceptive interference without attenuating the signal to far less than 1 photon per pulse. However, this solution requires the use of random numbers to perform random amplitude and phase modulation on the coherent state, requiring a random number generator and multiple electro-optic modulators and corresponding drive circuits, and the system is still relatively complex.

Summary of the invention

In order to solve the technical problems in the prior art such as limited active modulation accuracy, modulation error, large system noise and high circuit complexity, the present invention proposes a quantum safe laser radar device and ranging method based on a thermal light source.

To achieve the above object, the technical solution adopted by the present invention is as follows:

In one aspect, the present invention provides a quantum security laser radar device based on a thermal light source, comprising:

A thermal light source, used to generate a thermal light signal;

A narrowband filter for filtering the thermal optical signal;

An unbalanced beam splitting module, used for splitting the filtered thermal light signal to generate a first thermal light signal and a second thermal light signal with different intensities; wherein the first thermal light signal and the second thermal light signal are transmitted to the first conjugate homodyne detection module and the circulator respectively, and the intensity of the first thermal light signal is greater than the intensity of the second thermal light signal;

a circulator, for transmitting the second thermal state optical signal to the telescope, and for receiving the echo optical signal transmitted by the telescope, and transmitting the echo optical signal to the polarization processing module;

A telescope, used for receiving a second thermal state optical signal transmitted by the circulator, expanding the second thermal state optical signal and irradiating the target, and receiving an echo optical signal reflected by the target;

A polarization processing module, used to adjust the polarization state of the echo optical signal;

A local oscillator laser is used to generate a narrow linewidth optical signal as a local oscillator optical signal;

A first beam splitter is used to split the local oscillation light signal into a first local oscillation light component and a second local oscillation light component, wherein the first local oscillation light component and the second local oscillation light component are transmitted to a first conjugate homodyne detection module and a second conjugate homodyne detection module respectively;

A first conjugate homodyne detection module, used for measuring a canonical component of a first thermal state optical signal based on a first local oscillation optical component;

A second conjugate homodyne detection module is used to measure the regular component of the echo optical signal after the polarization state is adjusted based on the second local oscillation light component;

The narrowband filter and the local oscillator laser have the same central wavelength.

On the other hand, the present invention provides a distance measurement method, wherein the above-mentioned quantum security laser radar device based on a thermal light source performs the following steps:

Step S1: The thermal light signal generated by the thermal light source is filtered by a narrowband filter and then split into a first thermal light signal and a second thermal light signal with different intensities; the local oscillator laser generates a narrow linewidth light signal and is split into a first local oscillator light component and a second local oscillator light component;

Step S2: using the first local oscillation light component to perform conjugate homodyne detection on the first thermal light signal, to obtain a set of sequences {X1} and {P1} corresponding to the canonical coordinate component and the canonical momentum component; the second thermal light signal is used as the detection signal of the quantum security radar, irradiates the target object and is reflected to form an echo light signal;

Step S3: using the second local oscillation light component to perform conjugate homodyne detection on the echo light signal after polarization processing, to obtain another set of sequences {X2} and {P2} corresponding to the canonical coordinate components and the canonical momentum components;

Step S4: synchronously perform shift cross-correlation operation on the sequence {X1} and the sequence {X2}, the sequence {X1} and the sequence {P2}, the sequence {P1} and the sequence {X2}, and the sequence {P1} and the sequence {P2} to obtain four cross-correlation sequences. When at least one cross-correlation sequence has an obvious cross-correlation peak, the target distance is obtained.

Step S5: Calculate the phase shift value of the echo optical signal according to the cross-correlation peak value in step S4, and perform phase compensation on the sequences {X1} and {P1};

Step S6: According to the target distance obtained in step S4, the sequence {X1} and sequence {P1} after phase compensation in step S5 are aligned with the sequence {X2} and sequence {P2} respectively, and the system over-noise is estimated. When the over-noise is greater than the set threshold, it is determined that there is deception interference on the target.

The beneficial effects of the present invention are:

(1) The use of thermal light sources directly utilizes the randomness of the regular components of the light source itself, without the need to use a random number generator to generate random numbers. There is no need to use an electro-optical modulator to randomly modulate the amplitude and phase of the optical signal, eliminating the need for modulation devices and corresponding drive circuits, reducing the complexity of the system. No active modulation devices are required, making it easier to miniaturize and chip-based.

(2) No active modulation devices are required, eliminating the impact of limited modulation accuracy and modulation errors on the ability to detect deception interference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a structural diagram of a quantum safety laser radar device based on a thermal light source according to the present invention;

FIG2 is a structural diagram of a first embodiment of a quantum safety laser radar device based on a thermal light source according to the present invention;

FIG3 is a structural diagram of a second embodiment of a quantum safety laser radar device based on a thermal light source according to the present invention;

FIG4 is a structural diagram of a third embodiment of a quantum safety laser radar device based on a thermal light source according to the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

As shown in FIG1 , it is a structural diagram of a quantum safety laser radar device based on a thermal light source of the present invention, and the device includes:

A thermal light source, used to generate a thermal light signal;

A narrowband filter for filtering the thermal optical signal;

An unbalanced beam splitting module, used for splitting the filtered thermal light signal to generate a first thermal light signal and a second thermal light signal with different intensities; wherein the first thermal light signal and the second thermal light signal are transmitted to the first conjugate homodyne detection module and the circulator respectively, and the intensity of the first thermal light signal is greater than the intensity of the second thermal light signal;

a circulator, for transmitting the second thermal state optical signal to the telescope, and for receiving the echo optical signal transmitted by the telescope, and transmitting the echo optical signal to the polarization processing module;

A telescope, used for receiving a second thermal state optical signal transmitted by the circulator, expanding the second thermal state optical signal and irradiating the target, and receiving an echo optical signal reflected by the target;

A polarization processing module, used to adjust the polarization state of the echo optical signal;

A local oscillator laser is used to generate a narrow linewidth optical signal as a local oscillator optical signal;

A first beam splitter is used to split the local oscillation light signal into a first local oscillation light component and a second local oscillation light component, wherein the first local oscillation light component and the second local oscillation light component are transmitted to a first conjugate homodyne detection module and a second conjugate homodyne detection module respectively;

A first conjugate homodyne detection module, used for measuring a canonical component of a first thermal state optical signal based on a first local oscillation optical component;

A second conjugate homodyne detection module is used to measure the regular component of the echo optical signal after the polarization state is adjusted based on the second local oscillation light component;

The narrowband filter and the local oscillator laser have the same central wavelength.

Furthermore, the thermal light source also includes an optical fiber amplifier for amplifying the power of the thermal light signal.

The specific working process and principle are as follows:

The thermal light source generates a thermal light signal, and the average number of photons after filtering by a narrowband filter is , is split into a first thermal state light signal and a second thermal state light signal with different intensities by an unbalanced beam splitting module. The intensity of the first thermal state light signal is greater than that of the second thermal state light signal. The local oscillator laser generates a narrow linewidth light signal, which is split into a first local oscillator light component and a second local oscillator light component.

The first local oscillation light component and the first conjugate homodyne detection module are used to measure the canonical coordinate component and the canonical momentum component, ie, the X component and the P component, of the first thermal state light signal to obtain the sequence {X1} and the sequence {P1}.

The second thermal light signal is irradiated to the target after passing through the circulator and the telescope. After being reflected by the target, it forms an echo light signal which is transmitted to the polarization processing module through the telescope and the circulator again. After the polarization state is adjusted, it enters the second conjugate homodyne detection module. The X component and P component of the echo light signal are measured in combination with the second local oscillation light component to obtain the sequence {X2} and the sequence {P2}.

In actual situations, the measurement modes of the first thermal state optical signal and the echo optical signal cannot completely overlap. Assume that the measurement mode of the echo optical signal is , then the mode of measuring the first thermal state optical signal/> It can be written as:

,

in, Representation and Mode/> Vertical mode, /> and/> Respectively mode/> and mode/> The coefficient of , and/> .

Assuming that the unbalanced beam splitter module is a 50:50 beam splitter, and an attenuator is set on the optical path of the second thermal state optical signal, the measurement result of the X component of the first thermal state optical signal is It can be written as:

,

in, and/> are the detection efficiency and electrical noise of the first conjugate homodyne detection module, respectively, and/> They are respectively the modes in the thermal light source/> and/> The X component of is the vacuum noise introduced during beam splitting and detection.

X-component measurement results of the echo light signal for:

,

in, is the transmittance of the attenuator, /> is the overall efficiency of the emission, reception and target reflection of the second thermal state optical signal,/> and/> are the detection efficiency and electrical noise of the second conjugate homodyne detection module, respectively, The vacuum noise is introduced in the process of beam splitting, transmission and detection. The measurement results of the P component of the first thermal state optical signal and the echo optical signal are similar and will not be repeated here.

Sequence {X1} and sequence {P1} are respectively subjected to shift cross-correlation operation with sequence {X2} and sequence {P2} to measure the distance. Specifically, sequence {X1} and sequence {X2}, sequence {X1} and sequence {P2}, sequence {P1} and sequence {X2}, and sequence {P1} and sequence {P2} are synchronously subjected to shift cross-correlation operation to obtain four cross-correlation sequences.

For the sequence {X1} and the sequence {X2}, when they are the measurement results from different thermal state splitting, the two sequences are completely unrelated to each other, and the covariance of the two sequences is used to represent the cross-correlation value. Available:

,

in, is the mean of the variable, /> is the covariance of the two variables. Similarly, the other three cross-correlation results are also 0.

When the two are the measurement results from the same thermal state splitting, the cross-correlation between the two reaches a peak value, and we can get:

,

in, ,/> is the phase introduced during the transmission of the second thermal state optical signal, and there is a certain slow drift. The other three cross-correlation results can be calculated by the same method:

,

in, is the cross-correlation value between two variables i and j.

Depend on and/> Follow/> The change relationship of

When, /> , that is, when two of the four cross-correlation values are 0, the other two must reach the maximum value. If the absolute value of the cross-correlation value is taken, then for any phase , whose minimum value is/> Therefore, when performing the shifted cross-correlation operation, at least one cross-correlation sequence will have an obvious peak. At this time, the shift number N obtained by multiplying the system period T is the flight time of the second thermal state light signal, so that the target distance can be calculated./> , where c is the speed of light.

According to the above four cross-correlation values, the corresponding phase drift value can be calculated , and then the phase compensation can be performed on the sequences {X1} and {P1}. Then, the compensated sequences {X1} and {P1} are aligned with the sequences {X2} and {P2} respectively according to the shift number N or the target distance. Then, use /> Estimate the value of C and get the total noise of the system. Subtract the electrical noise of the conjugate homodyne detection module and the vacuum noise to get the excess noise of the system. When the excess noise is greater than the set threshold, it is judged that the target has deception interference.

Furthermore, as shown in FIG2 , an improved embodiment 1 of a quantum safety laser radar device based on a thermal light source of the present invention is provided:

The thermal light source comprises:

A first amplified spontaneous radiation light source is used to generate a wide-spectrum thermal state continuous light signal;

Polarizer, used to pass a thermal continuous light signal of a specific polarization state.

The unbalanced beam splitting module comprises:

A second beam splitter, used for splitting the filtered hot state light signal into a first hot state light signal and a second hot state light signal of equal intensity;

The attenuator is used to attenuate the second thermal state optical signal to a predetermined intensity.

The polarization processing module is a polarization controller, which is used to adjust the polarization state of the echo optical signal to horizontal polarization.

The first conjugate homodyne detection module includes a first 90° optical mixer and two balanced detectors.

The two input ports of the first 90° optical mixer are used to input the first thermal state optical signal and the first local oscillation optical component respectively;

Two output ports of the first 90° optical mixer are respectively connected to two input ports of a balanced detector, and the other two output ports are respectively connected to two input ports of another balanced detector BPD.

The second conjugate homodyne detection module includes a second 90° optical mixer and two balanced detectors.

The two input ports of the second 90° optical mixer are used to input the echo optical signal and the second local oscillation optical component respectively;

Two output ports of the second 90° optical mixer are respectively connected to two input ports of a balanced detector, and the other two output ports are respectively connected to two input ports of another balanced detector.

The specific working process and principle are as follows:

The first amplified spontaneous emission light source generates a thermal light signal, which is converted into a horizontal polarization state after passing through a polarizer, and then filtered by a narrowband filter to obtain an average photon number of , and then is split by the second beam splitter BS2 into a first thermal state light signal and a second thermal state light signal of the same intensity. The second thermal state light signal is then passed through a beam splitter with a transmittance of / The average number of photons becomes/> The local oscillator laser generates a narrow linewidth optical signal, which is split into a first local oscillator light component and a second local oscillator light component.

The first thermal state optical signal and the first local oscillator optical component enter the two input ports of the first 90° optical mixer respectively, and after 90° mixing, 4 interference optical signals are obtained and enter two balanced detectors for detection respectively, and the X component and P component of the first thermal state optical signal are measured to obtain the sequence {X1} and the sequence {P1}.

The second thermal light signal is irradiated to the target after passing through the circulator and the telescope. After being reflected by the target, an echo light signal is formed, which is transmitted to the polarization controller again through the telescope and the circulator. After the polarization state of the echo light signal is adjusted to horizontal polarization, it and the second local oscillation light component enter the two input ports of the second 90° mixer respectively. After 90° mixing, 4 interference light signals are obtained, which enter two balanced detectors for detection respectively, and the X component and P component of the echo light signal are measured to obtain the sequence {X2} and the sequence {P2}.

The sequence {X1} and the sequence {P1}, the sequence {X2} and the sequence {P2} can be processed according to the above method to achieve ranging and deception interference detection.

Furthermore, as shown in FIG3 , another improved embodiment 2 of a quantum safety laser radar device based on a thermal light source of the present invention is provided:

The thermal light source is a second amplified spontaneous emission light source, which is used to generate a horizontally polarized wide-spectrum thermal state light signal.

The unbalanced beam splitting module comprises:

A first half-wave plate, used to rotate the polarization state of the thermal optical signal to a predetermined angle;

The first polarization beam splitter is used for polarization-splitting the hot-state optical signal after polarization rotation into a first hot-state optical signal and a second hot-state optical signal with different intensities.

The polarization processing module is a polarization controller, which is used to adjust the echo optical signal to a horizontal polarization state.

The first conjugate homodyne detection module includes a first 90° optical mixer and two balanced detectors.

The two input ports of the first 90° optical mixer are used to input the first thermal state optical signal and the first local oscillation optical component respectively;

Two output ports of the first 90° optical mixer are respectively connected to two input ports of a balanced detector, and the other two output ports are respectively connected to two input ports of another balanced detector.

The second conjugate homodyne detection module includes a second polarization beam splitter, a third polarization beam splitter, a fourth beam splitter, a fifth beam splitter, a phase shifter and a balanced detector.

The two input ports of the second polarization beam splitter are used to input the echo optical signal and the second local oscillation optical component respectively, and the output port thereof is connected to the input port of the fourth beam splitter;

An output port of the fourth beam splitter is connected to an input port of the fifth beam splitter via a first optical fiber;

An input port and an output port of the third polarization beam splitter are connected to another output port of the fourth beam splitter and another input port of the fifth beam splitter through the second optical fiber and the third optical fiber respectively;

Another input port and another output port of the third polarization beam splitter are connected to the phase shifter via a fourth optical fiber;

The length of the first optical fiber is longer than the sum of the lengths of the second optical fiber and the third optical fiber. t, the length of the fourth optical fiber is v/> t, where v is the speed of light in the optical fiber, and t is the time difference between the echo light signal and the second local oscillator light component entering the second polarization beam splitter;

The two output ports of the fifth beam splitter are respectively connected to the two input ports of the balanced detector.

The specific working process and principle are as follows:

The second amplified spontaneous emission light source generates a thermal light signal with a horizontal polarization state. After filtering by a narrowband filter, the average photon number is , and then the polarization is rotated by the first half-wave plate, and the angle between the polarization direction and the horizontal direction becomes/> , is split by the first polarization beam splitter into a first thermal state light signal and a second thermal state light signal with different intensities, and the average photon numbers of the two are respectively/> and/> The local oscillator laser generates a narrow linewidth optical signal, which is split into a first local oscillator light component and a second local oscillator light component.

The first thermal state optical signal and the first local oscillator optical component enter the two input ports of the first 90° optical mixer respectively, and after 90° mixing, 4 interference optical signals are obtained and enter two balanced detectors for detection respectively, and the X component and P component of the first thermal state optical signal are measured to obtain the sequence {X1} and the sequence {P1}.

The second thermal light signal irradiates the target after passing through the circulator and the telescope. After being reflected by the target, it forms an echo light signal, which is then transmitted to the polarization controller through the telescope and the circulator again to adjust the echo light signal to a horizontal polarization state. Then, the echo light signal and the second local oscillation light component successively enter the input port of the second polarization beam splitter, where the echo light signal is still in a horizontal polarization state, and the second local oscillation light component becomes a vertical polarization state. The two enter the fourth beam splitter and are respectively split into the first echo component and the second echo component, the third local oscillation light component and the fourth local oscillation light component with the same amplitude, where the first echo component and the third local oscillation light component propagate along the first optical fiber, and the second echo component and the fourth local oscillation light component propagate along the second optical fiber. After reaching the third polarization beam splitter, the second echo component enters the fourth optical fiber for propagation, and is phase shifted 90° by the phase shifter, and then returns to the third polarization beam splitter and enters the third optical fiber, becoming a vertical polarization state; after reaching the third polarization beam splitter, the fourth local oscillation light component directly enters the third optical fiber and becomes a horizontal polarization state. Since the first optical fiber is longer than the sum of the lengths of the second optical fiber and the third optical fiber by v t, that is, the time for the first echo component to propagate in the first optical fiber is longer than the time for the fourth local oscillator light component to propagate in the second optical fiber and the third optical fiber, which just offsets the time difference t between the two components when they are emitted from the two output ports of the fourth beam splitter. Therefore, the first echo component and the fourth local oscillator light component arrive at the two input ports of the fifth beam splitter at the same time, and after interference, two interference light signals are obtained and enter the balanced detector for detection, and the X component of the echo light signal is measured to obtain the sequence {X2}. The second echo component is transmitted through the second optical fiber to the third polarization beam splitter and then enters the fourth optical fiber. The polarization state remains unchanged. Then, it returns to the third polarization beam splitter through the phase shifter and enters the fourth optical fiber again, changing to a vertical polarization state. After a 90° phase shift, it is emitted from the third polarization beam splitter and reaches an input port of the fifth beam splitter through the third optical fiber. Therefore, the transmission time of the second echo component in the second optical fiber, the third optical fiber, and the fourth optical fiber is t more than the transmission time of the third local oscillation light component in the first optical fiber. Since the time difference between the second echo component and the third local oscillation light component from the two output ports of the fourth beam splitter is t, the second echo component and the third local oscillation light component simultaneously arrive at the two input ports of the fifth beam splitter. After interference, two interference light signals are obtained and enter the balanced detector for detection, which is delayed by time t compared with the interference signal of the first echo component and the fourth local oscillation light component. Finally, the P component of the echo light signal can be measured to obtain the sequence {P2}.

The sequence {X1} and the sequence {P1}, the sequence {X2} and the sequence {P2} can be processed according to the above method to achieve ranging and deception interference detection.

Further, as shown in FIG4 , another improved embodiment 3 of a quantum safety laser radar device based on a thermal light source of the present invention is provided:

The thermal light source is a second amplified spontaneous radiation light source, which is used to generate a horizontally polarized wide-spectrum thermal state light signal.

The unbalanced beam splitting module is a third beam splitter with an adjustable beam splitting ratio.

The polarization processing module includes a polarization controller and a quarter wave plate, which are used to adjust the echo optical signal to a circular polarization state.

The first conjugate homodyne detection module includes a first 90° optical mixer and two balanced detectors.

The two input ports of the first 90° optical mixer are used to input the first thermal state optical signal and the first local oscillation optical component respectively;

Two output ports of the first 90° optical mixer are respectively connected to two input ports of a balanced detector, and the other two output ports are respectively connected to two input ports of another balanced detector.

The second conjugate homodyne detection module includes a fourth polarization beam splitter, a fifth polarization beam splitter, a second half-wave plate, a third half-wave plate and a balanced detector.

The two input ports of the fourth polarization beam splitter are respectively used to input the echo optical signal and the second local oscillation optical component, and the two output ports thereof are respectively connected to the two input ports of the fifth polarization beam splitter through optical paths of different lengths;

The two output ports of the fifth polarization beam splitter are respectively connected to the two input ports of the balanced detector;

The second half-wave plate is arranged on a shorter optical path connecting the fourth polarization beam splitter and the fifth polarization beam splitter;

The third half-wave plate is arranged on a longer optical path connecting the fourth polarization beam splitter and the fifth polarization beam splitter;

The angles between the main axis directions of the second half-wave plate and the third half-wave plate and the horizontal polarization direction are both 22.5°.

The specific working process and principle are as follows:

The second amplified spontaneous emission light source generates a thermal light signal with a horizontal polarization state. After filtering by the narrowband filter BPF, the average photon number is , and then split into a first thermal state optical signal and a second thermal state optical signal with different intensities by a third beam splitter. The local oscillator laser generates a narrow linewidth optical signal, which is split into a first local oscillator optical component and a second local oscillator optical component.

The first thermal state optical signal and the first local oscillator optical component enter the two input ports of the first 90° optical mixer respectively, and after 90° mixing, 4 interference optical signals are obtained and enter two balanced detectors for detection respectively, and the X component and P component of the first thermal state optical signal are measured to obtain the sequence {X1} and the sequence {P1}.

The second thermal light signal is irradiated to the target after passing through the circulator and the telescope. After being reflected by the target, it forms an echo light signal which is transmitted to the polarization controller again through the telescope and the circulator to adjust the echo light signal to a horizontal polarization state. The echo light signal is then converted into a circular polarization state through a quarter-wave plate whose main axis direction is at an angle of 45° to the horizontal polarization direction, and enters an input port of the fourth polarization beam splitter to be polarized into a first echo component and a second echo component with the same amplitude, which have a phase difference of 90°. The second local oscillation light component enters another input port of the fourth polarization beam splitter and is polarized into a third local oscillation light component and a fourth local oscillation light component with the same amplitude.

The first echo component and the third local oscillation light component are emitted from an output port of the fourth polarization beam splitter at the same time. The polarizations of the two components are perpendicular to each other. After passing through the second half-wave plate, they interfere with each other. After being polarized and split by the fifth polarization beam splitter, they are emitted from its two output ports. Finally, they enter the balanced detector for detection, and the X component of the echo light signal is measured to obtain the sequence {X2}.

The second echo component and the fourth local oscillation light component are emitted from the other output port of the fourth polarization beam splitter at the same time. The polarizations of the two components are perpendicular to each other. After interference through the third half-wave plate, they are polarized and split by the fifth polarization beam splitter and emitted from its two output ports. Finally, they enter the balanced detector for detection, and the P component of the echo light signal is measured to obtain the sequence {P2}. Since the optical path lengths connecting the two output ports of the fourth polarization beam splitter PS3 and the two input ports of the fifth polarization beam splitter are different, the balanced detector performs time-division multiplexing measurement on the X component and the P component of the echo light signal.

The sequence {X1} and the sequence {P1}, the sequence {X2} and the sequence {P2} can be processed according to the above method to achieve ranging and deception interference detection.

The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (14)

1. A quantum security laser radar apparatus based on a thermal light source, comprising:

A thermal light source for generating a thermal state light signal;

the narrow-band filter is used for filtering the thermal state optical signals;

The unbalanced beam splitting module is used for splitting the filtered thermal state optical signals to generate a first thermal state optical signal and a second thermal state optical signal with different intensities; the first thermal state optical signal and the second thermal state optical signal are respectively transmitted to the first conjugate homodyne detection module and the circulator, and the intensity of the first thermal state optical signal is larger than that of the second thermal state optical signal; the second thermal state optical signal comprises a quantum fluctuation signal;

The circulator is used for transmitting the second thermal state optical signal to the telescope, receiving the echo optical signal transmitted by the telescope and transmitting the echo optical signal to the polarization processing module;

A telescope for receiving the second thermal state optical signal transmitted by the circulator, irradiating the target after expanding the beam of the second thermal state optical signal, and receiving the echo optical signal reflected by the target;

the polarization processing module is used for adjusting the polarization state of the echo optical signal;

the local oscillator laser is used for generating a narrow linewidth optical signal and used as a local oscillator optical signal;

The first beam splitter is used for splitting the local oscillation optical signal into a first local oscillation optical component and a second local oscillation optical component, wherein the first local oscillation optical component and the second local oscillation optical component are respectively transmitted to the first conjugate homodyne detection module and the second conjugate homodyne detection module;

The first conjugate homodyne detection module is used for measuring the regular component of the first thermal state optical signal based on the first local oscillation optical component;

The second conjugate homodyne detection module is used for measuring the regular component of the echo optical signal after the polarization state is adjusted based on the second local oscillation optical component;

the center wavelength of the narrow-band filter is the same as that of the local oscillator laser.

2. The thermal light source-based quantum security lidar device of claim 1, wherein the thermal light source comprises:

A first amplified spontaneous emission light source for generating a broad-spectrum thermal-state continuous optical signal;

and the polarizer is used for transmitting the thermal state continuous optical signal with a specific polarization state.

3. The quantum security laser radar apparatus based on a thermal light source according to claim 1, wherein the thermal light source is a second amplified spontaneous emission light source for generating a horizontally polarized broad spectrum thermal state light signal.

4. A quantum security laser radar apparatus based on a thermal light source as claimed in claim 2 or 3, wherein the thermal light source further comprises an optical fiber amplifier for amplifying the power of the thermal state optical signal.

5. The thermal light source-based quantum security lidar device of claim 1, wherein the unbalanced beam splitting module comprises:

The second beam splitter is used for splitting the filtered thermal state optical signal into a first thermal state optical signal and a second thermal state optical signal with equal intensity;

And an attenuator for attenuating the second thermal state optical signal to a predetermined intensity.

6. The thermal light source-based quantum security lidar device of claim 1, wherein the unbalanced beam splitting module comprises:

The first half wave plate is used for rotating the polarization state of the thermal state optical signal to a preset angle;

The first polarization beam splitter is used for polarization splitting the thermal state optical signal after the polarization state is rotated to a preset angle into a first thermal state optical signal and a second thermal state optical signal with different intensities.

7. The quantum security laser radar apparatus based on a thermal light source according to claim 1, wherein the unbalanced beam splitting module is a third beam splitter with an adjustable beam splitting ratio.

8. The quantum security laser radar apparatus based on the thermal light source according to claim 1, wherein the polarization processing module is a polarization controller for adjusting the polarization state of the echo light signal to be horizontal polarization.

9. The thermal light source-based quantum security laser radar apparatus of claim 1, wherein the polarization processing module comprises a polarization controller and a quarter wave plate for adjusting the echo light signal to a circular polarization state.

10. The quantum security laser radar apparatus based on a thermal light source according to claim 1, wherein the first conjugate homodyne detection module comprises a first 90 ° optical mixer and two balanced detectors,

The two input ports of the first 90-degree optical mixer are respectively used for inputting a first thermal state optical signal and a first local oscillation optical component;

Two output ports of the first 90-degree optical mixer are respectively connected with two input ports of one balance detector, and the other two output ports of the first 90-degree optical mixer are respectively connected with two input ports of the other balance detector.

11. The quantum security laser radar apparatus based on the thermal light source according to claim 8, wherein the second conjugate homodyne detection module comprises a second 90 ° optical mixer and two balance detectors,

Two input ports of the second 90-degree optical mixer are respectively used for inputting an echo optical signal and a second local oscillation optical component;

Two output ports of the second 90-degree optical mixer are respectively connected with two input ports of one balance detector, and the other two output ports of the second 90-degree optical mixer are respectively connected with two input ports of the other balance detector.

12. The thermal light source-based quantum security laser radar apparatus of claim 8, wherein the second conjugate homodyne detection module comprises:

A second polarizing beam splitter, a third polarizing beam splitter, a fourth beam splitter, a fifth beam splitter, a phase shifter, and a balanced detector,

The two input ports of the second polarization beam splitter are respectively used for inputting an echo optical signal and a second local oscillation optical component, and the output port of the second polarization beam splitter is connected with the input port of the fourth polarization beam splitter;

an output port of the fourth beam splitter is connected with an input port of the fifth beam splitter through a first optical fiber;

One input port and one output port of the third polarization beam splitter are connected with the other output port of the fourth beam splitter and the other input port of the fifth beam splitter through a second optical fiber and a third optical fiber respectively;

The other input port and the other output port of the third polarization beam splitter are connected with the phase shifter through a fourth optical fiber;

The length of the first optical fiber is longer than the sum of the lengths of the second optical fiber and the third optical fiber by v T, the length of the fourth optical fiber is v/>T, wherein v is the light velocity in the optical fiber, and t is the time difference between the echo light signal and the second local oscillation light component entering the second polarization beam splitter;

and two output ports of the fifth beam splitter are respectively connected with two input ports of the balance detector.

13. The thermal light source-based quantum security laser radar apparatus of claim 9, wherein the second conjugate homodyne detection module comprises:

The device comprises a fourth polarization beam splitter, a fifth polarization beam splitter, a second half-wave plate, a third half-wave plate and a balance detector;

the two input ports of the fourth polarization beam splitter are respectively used for inputting echo optical signals and second local oscillation optical components, and the two output ports of the fourth polarization beam splitter are respectively connected with the two input ports of the fifth polarization beam splitter through optical paths with different lengths;

two output ports of the fifth polarization beam splitter are respectively connected with two input ports of the balance detector;

the second half-wave plate is arranged on a shorter light path of the fourth polarization beam splitter connected with the fifth polarization beam splitter;

The third half-wave plate is arranged on a longer light path of the fourth polarization beam splitter connected with the fifth polarization beam splitter;

And the included angles between the principal axis direction and the horizontal polarization direction of the second half wave plate and the third half wave plate are 22.5 degrees.

14. A ranging method applied to the quantum security laser radar device based on the thermal light source as claimed in any one of claims 1 to 13, characterized in that the method comprises the following steps:

Step S1: the method comprises the steps that a thermal state optical signal generated by a thermal light source is filtered by a narrow-band filter and then split into a first thermal state optical signal and a second thermal state optical signal with different intensities, and a local oscillator laser generates a narrow-linewidth optical signal and is split into a first local oscillator optical component and a second local oscillator optical component;

step S2: performing conjugate homodyne detection on the first thermal state optical signal by using the first local oscillation optical component to obtain a group of sequences { X1} and sequences { P1} corresponding to the regular coordinate component and the regular momentum component; the second thermal state optical signal is used as a detection signal of the quantum safety radar, and an echo optical signal is formed after the irradiation target object is reflected;

Step S3: performing conjugate homodyne detection on the echo optical signal subjected to polarization processing by using a second local oscillation optical component to obtain a sequence { X2} and a sequence { P2} corresponding to the other group of regular coordinate components and the regular momentum components;

Step S4: carrying out shift cross-correlation operation on the sequence { X1} and the sequence { X2}, the sequence { X1} and the sequence { P2}, the sequence { P1} and the sequence { X2}, and the sequence { P1} and the sequence { P2} synchronously to obtain 4 cross-correlation sequences, and obtaining a target distance when at least one cross-correlation sequence has obvious cross-correlation peak values;

Step S5: calculating a phase drift value of the echo optical signal according to the cross correlation peak value in the step S4, and carrying out phase compensation on the sequences { X1} and { P1 };

Step S6: and (3) aligning the sequence { X1} and the sequence { P1} after the phase compensation in the step (5) with the sequence { X2} and the sequence { P2} respectively according to the target distance obtained in the step (4), estimating the over-noise of the system, and judging that the target is deceptive according to the condition that the over-noise is larger than a set threshold value.