A laser ranging and echo detection system and method based on photonic transistors

Abstract

This invention discloses a laser ranging echo detection system and method based on photonic transistors. The system includes: a digital control system, a laser emitting device, an emitting optical system, a PIN photodetector 1, a main wave amplifier, a receiving optical system, a reflector, a photonic transistor, an echo detection system light source, a PIN photodetector 2, and the target object to be measured. The method of this invention utilizes a simple photonic transistor structure, small device size, and is easy to integrate on a large scale. It replaces existing photodetectors by using the echo signal as the pump light for the photonic transistor, rather than directly measuring the echo signal. This improves the sensitivity and testing distance of pulsed laser ranging to weak echo signals, and achieves high-precision laser ranging without requiring excessively high photodetector bias voltage and source signal intensity.

Description

Technical Field

[0001] This invention relates to the field of laser ranging echo detection technology, and specifically to a laser ranging echo detection system and method based on photonic transistors. Background Technology

[0002] Laser ranging technology has been widely used due to its advantages such as good directionality, high brightness, and good coherence. Among them, pulsed laser ranging technology has advantages such as high measurement accuracy, long measurement distance, and the ability to detect targets without cooperation. The main principle of pulsed laser ranging technology is to emit laser pulses through a transmitting device. After the pulses reach the target object, they undergo diffuse reflection and are finally received by an echo detection system. By measuring the time interval t between the emitted laser pulse and the echo laser pulse, the distance D of the target object can be calculated using the formula D = c * t / 2, where c represents the speed of light. It is evident that to achieve high-precision pulsed laser ranging, accurate measurement of the time interval t between the emitted and echo laser pulses is necessary, which heavily relies on high-precision echo detection technology.

[0003] Existing laser ranging technology is limited by the development of echo detection technology and has the following problems: as the ranging distance increases and environmental interference occurs, the echo signal will be severely attenuated. Traditional photoelectric detection devices (such as APD, PIN, PMT, etc.) are difficult to achieve high-precision detection of weak echo signals. This not only restricts the ranging range of the laser ranging system, but also increases the environmental requirements for the use of the laser ranging system.

[0004] A photonic transistor is an optical nanodevice that can achieve optical switching and gain effects. Photonic transistors exhibit extremely high sensitivity to weak light signals, and their response time can reach the picosecond level. Furthermore, unlike traditional photodetectors which are affected by environmental factors such as temperature, photonic transistors, as all-optical devices, do not generate excess heat during operation.

[0005] Currently, achieving high sensitivity and short response time in echo detection technology has been a hot topic in the field of laser ranging, but there is still no solution to apply photonic transistors to improve the performance of laser ranging echo detection systems. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a laser ranging echo detection system and method based on photonic transistors, which can sensitively and rapidly detect weak echo signals, thereby improving the accuracy and testing distance of laser ranging.

[0007] The technical solution adopted in this invention is as follows: a laser ranging echo detection system based on photonic transistors, comprising: 1 digital control system, 2 laser emitting device, 3 emitting optical system, 4 PIN photodetector 1, 5 main wave amplifier, 6 receiving optical system, 7 reflector, 8 photonic transistor, 9 echo detection system light source, 10 PIN photodetector 2, and 11 target object to be measured.

[0008] 1. The digital control system is connected to 2. The laser emitting device is connected to 3. The emitting optical system is connected to 4. The photodetector 1 emits laser pulse signals to 11. The photodetector 1 is connected to 5. The main wave amplifier is connected to 1. The digital control system is connected to 1. The photodetector 1 diffusely reflects the laser pulse signals to 6. The receiving optical system is connected to 7. The reflector is connected to 8. The phototransistor is connected to 10. The photodetector 2 is connected to 10. The echo detection system light source is connected to 8. The phototransistor 2 is connected to 1. The digital control system is connected to 1.

[0009] Furthermore, the second laser emitting device employs an Nd:YAG pulsed laser with a wavelength of 1064nm.

[0010] Furthermore, the 3-emission optical system consists of a 301 beam expander and a 302 beam splitter. After the emitted laser pulse passes through the 3-emission optical system, it is expanded and split, and then enters the target objects to be measured by the 4-PIN photodetectors 1 and 11, respectively.

[0011] Furthermore, the 6-receiving optical system consists of a 601 receiving lens and a 602 narrowband filter. After passing through the 6-receiving optical system, the echo laser pulse enters the 8-photon transistor as pump light.

[0012] Furthermore, in the absence of pump light, the 8-photon transistor exhibits reflective properties towards the source signal light emitted by the 9-echo detection system light source; that is, no photons can pass through the 8-photon transistor and be received by the 10-pin photodetector 2. In the presence of pump light, the 8-photon transistor exhibits transmissive and amplified properties towards the source signal light emitted by the 9-echo detection system light source; that is, photons can pass through the 8-photon transistor and be received by the 10-pin photodetector 2.

[0013] Furthermore, the 8-photon transistor structure includes: a 12-nanometer wire, a 13-low-loss dielectric waveguide, and a 14-single-photon emitter. The 12-nanometer wire is made of silver material with a dielectric constant ε≈-50+0.6i, featuring a subwavelength-scale cylindrical structure at one end and an hourglass-shaped structure with a gradually decreasing radius in the middle. The 13-low-loss dielectric waveguide is made of a material with a dielectric constant ε=2 and is partially coupled to the 12-nanometer wire. The 14-single-photon emitter is a CdSe / ZnS quantum dot, a CdSe / CdS quantum dot, a ZnCdSe / ZnS quantum dot, or a perovskite quantum dot.

[0014] Furthermore, the pump light input port of the 8-photon transistor is a port of the low-loss dielectric waveguide 13; the source signal light input port of the 8-photon transistor is at the single-photon emitter 14.

[0015] This invention also provides a laser ranging echo detection method based on photonic transistors, the specific steps of which are as follows:

[0016] S1. Connect the 1 digital control system and the 2 laser emitting device in sequence. The 2 laser emitting device generates emitted laser pulses, which are then split by the 3 emitting optical system.

[0017] S2. Part of the laser pulse signal split in step S1 enters the 4PIN photodetector 1, and then is amplified by the 5 main wave amplifier. The start timing signal is then transmitted to the 1 digital control system to record the laser pulse emission time t1.

[0018] S3. The laser pulse signal split in step S1, the other part is directed towards the target object 11 and diffusely reflected by the target object 11. The subsequent echo laser pulse passes through the receiving optical system 6 and the reflecting mirror 7 and is used as the pump light of the 8 photonic transistor to control the start of the 8 photonic transistor. The echo detection system light source 9 provides the source signal light for the 8 photonic transistor.

[0019] S4. Upon receiving the echo laser pulse, the 8-photon transistor exhibits transmission and gain. The source signal light is transmitted through the 8-photon transistor and detected by the 10-pin photodetector 2, serving as the end timing signal. Finally, it is transmitted to the 1 digital control system to complete the detection of the distance to the target object.

[0020] Furthermore, step S4 specifically includes the following:

[0021] Record the echo laser pulse time t2, calculate the time interval t = t1 - t2 between the emitted laser pulse and the echo laser pulse, and calculate the distance D of the target object using the formula D = c * t / 2.

[0022] Where c represents the speed of light.

[0023] Furthermore, the process of using the 8-photon transistor to achieve laser ranging echo detection is as follows:

[0024] The echo laser pulse is received by the receiving optical system (6) and the reflecting mirror (7), and then guided into the pump light inlet of the photonic transistor (8). The photon enters the low-loss dielectric waveguide (13). The photon is transmitted to the coupling point between the low-loss dielectric waveguide (13) and the 12 nanowire, where it is transferred to the 12 nanowire and excites surface plasmon polaritons. The strong interaction between the surface plasmon polaritons and the single-photon emitter (14) causes a change in the energy level of the single-photon emitter. The single-photon emitter changes from reflecting the source signal light to transmitting and gaining power. At this time, the source signal light emitted by the echo detection system (9) can be transmitted through the photonic transistor (8), transmitting the end-of-timing signal. After the surface plasmon polaritons are excited on the 12 nanowire, the light is transferred back to the low-loss dielectric waveguide (13).

[0025] The beneficial effects of this invention are as follows: The system of this invention includes: a digital control system, a laser emitting device, an emitting optical system, a PIN photodetector 1, a main wave amplifier, a receiving optical system, a reflector, a photonic transistor, an echo detection system light source, a PIN photodetector 2, and the target object to be measured. The method of this invention uses a simple photonic transistor structure, small device size, and is easy to integrate on a large scale. It replaces existing photodetectors, using the echo signal as the pump light for the photonic transistor instead of directly measuring the echo signal. This improves the sensitivity and testing distance of pulsed laser ranging to weak echo signals, and achieves high-precision laser ranging without requiring excessively high photodetector bias voltage and source signal light intensity. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a laser ranging and echo detection system based on photonic transistors according to the present invention.

[0027] Figure 2 This is a characteristic diagram of the photonic transistor in an embodiment of the present invention when there is no pump light.

[0028] Figure 3 This is a characteristic diagram of the photonic transistor in an embodiment of the present invention when pump light is present.

[0029] Figure 4 This is a structural diagram of a photonic transistor in an embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the energy levels of the photonic transistor in the initialization state in an embodiment of the present invention.

[0031] Figure 6 This is a schematic diagram of the energy levels of the photonic transistor in an embodiment of the present invention when no photons are detected.

[0032] Figure 7 This is a schematic diagram of the energy levels of the photonic transistor when it detects a photon in an embodiment of the present invention. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0034] like Figure 1 As shown in the figure, a schematic diagram of a laser ranging echo detection system based on photonic transistors according to the present invention includes: 1 digital control system, 2 laser emitting device, 3 emitting optical system, 4 PIN photodetector 1, 5 main wave amplifier, 6 receiving optical system, 7 reflector, 8 photonic transistor, 9 echo detection system light source, 10 PIN photodetector 2, and 11 target object to be measured.

[0035] 1. The digital control system is connected to 2. The laser emitting device is connected to 3. The emitting optical system is connected to 4. The photodetector 1 emits laser pulse signals to 11. The photodetector 1 is connected to 5. The main wave amplifier is connected to 1. The digital control system is connected to 1. The photodetector 1 diffusely reflects the laser pulse signals to 6. The receiving optical system is connected to 7. The reflector is connected to 8. The phototransistor is connected to 10. The photodetector 2 is connected to 10. The echo detection system light source is connected to 8. The phototransistor 2 is connected to 1. The digital control system is connected to 1.

[0036] In this embodiment, the second laser emitting device employs an Nd:YAG pulsed laser with a wavelength of 1064 nm. This wavelength is within the atmospheric window, greatly reducing atmospheric attenuation of the laser, and the material used in the photonic transistor has high sensitivity to laser pulses with a wavelength of 1064 nm.

[0037] In this embodiment, the 3-emission optical system consists of a 301 beam expander and a 302 beam splitter. After the emitted laser pulse passes through the 3-emission optical system, it is expanded and split, and then enters the target objects to be measured by the 4-PIN photodetectors 1 and 11, respectively.

[0038] In this embodiment, the 6-receiving optical system consists of a 601 receiving lens and a 602 narrowband filter. After the echo laser pulse passes through the 6-receiving optical system, it enters the 8-photon transistor as pump light.

[0039] In this embodiment, as Figure 2As shown, the 8-photon transistor exhibits reflection characteristics of the source signal light in the absence of pump light, preventing the source signal light from propagating further. That is, it reflects the source signal light emitted by the 9-echo detection system light source, and no photons can pass through the 8-photon transistor to be received by the 10-pin photodetector 2. Figure 3 As shown, the 8-photon transistor exhibits transmission and gain characteristics for the source signal light when pump light is present. The source signal light can pass through the photon transistor normally and obtain a certain gain effect. The magnitude of the gain depends on the magnitude of the pump light. That is, it exhibits transmission and gain characteristics for the source signal light emitted by the source light source of the 9-echo detection system. Photons can be transmitted through the 8-photon transistor and received by the 10-pin photodetector 2.

[0040] like Figure 4 As shown, in this embodiment, the 8-photon transistor structure includes: a 12-nanometer wire, a 13-low-loss dielectric waveguide, and a 14-single-photon emitter. The 12-nanometer wire is made of silver material with a dielectric constant ε≈-50+0.6i. Its ends are subwavelength-scale cylindrical structures, providing good confinement and generating a large coupling constant, enhancing the excitation of surface plasmon polaritons. The middle portion is an hourglass-shaped structure with a gradually decreasing radius, exhibiting significant field concentration and enhancing the interaction between surface plasmon polaritons and the single-photon emitter. The 13-low-loss dielectric waveguide is made of a material with a dielectric constant ε=2 and is partially coupled to the 12-nanometer wire. The 14-single-photon emitter is a CdSe / ZnS quantum dot, a CdSe / CdS quantum dot, a ZnCdSe / ZnS quantum dot, or a perovskite quantum dot.

[0041] In this embodiment, the pump light input port of the 8-photon transistor is a port of the low-loss dielectric waveguide 13; the source signal light input port of the 8-photon transistor is at the single-photon emitter 14.

[0042] This invention also provides a laser ranging echo detection method based on photonic transistors, the specific steps of which are as follows:

[0043] S1. Connect the 1 digital control system and the 2 laser emitting device in sequence. The 2 laser emitting device generates emitted laser pulses, which are then split by the 3 emitting optical system.

[0044] S2. Part of the laser pulse signal split in step S1 enters the 4PIN photodetector 1, and then is amplified by the 5 main wave amplifier. The start timing signal is then transmitted to the 1 digital control system to record the laser pulse emission time t1.

[0045] S3. The laser pulse signal split in step S1, the other part is directed towards the target object 11 and diffusely reflected by the target object 11. The subsequent echo laser pulse passes through the receiving optical system 6 and the reflecting mirror 7 and is used as the pump light of the 8 photonic transistor to control the start of the 8 photonic transistor. The echo detection system light source 9 provides the source signal light for the 8 photonic transistor.

[0046] S4. Upon receiving the echo laser pulse, the 8-photon transistor exhibits transmission and gain. The source signal light is transmitted through the 8-photon transistor and detected by the 10-pin photodetector 2, serving as the end timing signal. Finally, it is transmitted to the 1 digital control system to complete the detection of the distance to the target object.

[0047] In this embodiment, step S4 specifically includes the following:

[0048] Record the echo laser pulse time t2, calculate the time interval t = t1 - t2 between the emitted laser pulse and the echo laser pulse, and calculate the distance D of the target object using the formula D = c * t / 2.

[0049] Where c represents the speed of light.

[0050] In this embodiment, the process of using the 8 photonic transistors to achieve laser ranging echo detection is as follows:

[0051] The echo laser pulse is received by the receiving optical system (6) and the reflecting mirror (7), and then guided into the pump light inlet of the photonic transistor (8). The photon enters the low-loss dielectric waveguide (13). The photon is transmitted to the coupling point between the low-loss dielectric waveguide (13) and the 12 nanowire, where it is transferred to the 12 nanowire and excites surface plasmon polaritons. The strong interaction between the surface plasmon polaritons and the single-photon emitter (14) causes a change in the energy level of the single-photon emitter. The single-photon emitter changes from reflecting the source signal light to transmitting and gaining power. At this time, the source signal light emitted by the echo detection system (9) can be transmitted through the photonic transistor (8), transmitting the end-of-timing signal. After the surface plasmon polaritons are excited on the 12 nanowire, the light is transferred back to the low-loss dielectric waveguide (13).

[0052] like Figure 5 As shown, the diagram illustrates the energy levels of an 8-photon transistor in its initial state. The 14 single-photon emitters of the 8-photon transistor contain three energy levels: the ground state |g>, the metastable state |s>, and the excited state |e>.

[0053] In this system, the ground state |g> and the excited state |e> are coupled through a surface plasmon mode, while the metastable state |s> has different dipole moment directions and is therefore decoupled from the surface plasmon polaritons. However, the metastable state |s> is resonantly coupled to the Rabi frequency Ω(t) through an optical control field. Initializing the laser ranging and echo detection system based on an 8-photon transistor requires adjusting the control field Ω(t) so that the 14 single-photon emitters are in the ground state |g> under the combined influence of the ambient light field and the control field Ω(t).

[0054] like Figure 6 The diagram shows the energy levels of an 8-photon transistor when no photon is detected. After initializing the 8-photon transistor with a suitable control field Ω(t), impedance matching is achieved, and the 8-photon transistor can capture the incident photon, simultaneously inducing a spin flip of the 14 single-photon emitter from the ground state |g> to the metastable state |s>. When no photon is detected, i.e., no pump light reaches the 8-photon transistor, the 14 single-photon emitter remains in the ground state |g>. In this case, the 8-photon transistor exhibits reflection, meaning the source signal light cannot pass through the 8-photon transistor.

[0055] like Figure 7 The diagram shows the energy levels of an 8-photon transistor when it detects a photon. Upon detection, i.e., when pump light reaches the 8-photon transistor, it captures the incident photon and simultaneously induces a spin flip of the 14 single-photon emitters from the ground state |g> to the metastable state |s>. Since the metastable state |s> has different dipole moment directions, decoupling occurs, and the 8-photon transistor exhibits high transmission. The source signal light passes normally through the 8-photon transistor, and then the timing information is transmitted back to the 1-digital control system.

[0056] Regarding the gain effect of the 8-photon transistor, due to the decay rate Γ of the 14 single-photon emitter from the excited state |e> to the ground state |g>... e→g It must be greater than the occurrence rate of surface plasmon polaritons Γ pl , that is Γ e→g ≥Γ pl This results in the 8-photon transistor capturing the incident pump photon and inducing a spin flip from the ground state |g> to the metastable state |s>. During this process, the 14 single-photon emitter has a high probability of directly decaying from the excited state |e> to the ground state |g> and emitting a photon, which provides gain for the source signal light that passes through the 8-photon transistor.

[0057] As can be seen from the above specific implementation scheme, this invention provides a laser ranging echo detection system and method based on photonic transistors. This invention uses photonic transistors to indirectly detect echo signals, solving the problem that traditional laser ranging techniques based on classical photoelectric detectors cannot achieve ranging of weak echoes from long-distance non-cooperative targets. It cleverly utilizes the high sensitivity and gain characteristics of photonic transistors to improve laser ranging measurement performance.

[0058] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A laser ranging and echo detection system based on photonic transistors, comprising: Digital control system (1), laser emitting device (2), emitting optical system (3), PIN photodetector 1 (4), main wave amplifier (5), receiving optical system (6), reflector (7), photonic transistor (8), echo detection system light source (9), PIN photodetector 2 (10), target object to be tested (11); The digital control system (1) is connected to the laser emitting device (2); the laser emitting device (2) is connected to the emitting optical system (3); the emitting optical system (3) is connected to the PIN photodetector 1 (4) and emits laser pulse signals to the target object (11); the PIN photodetector 1 (4) is connected to the main wave amplifier (5); the main wave amplifier (5) is connected to the digital control system (1); the target object (11) diffusely reflects the laser pulse signals to the receiving optical system (6); the receiving optical system (6) is connected to the reflector (7); the reflector (7) is connected to the photonic transistor (8); the photonic transistor (8) is connected to the PIN photodetector 2 (10); the echo detection system light source (9) is connected to the photonic transistor (8); the PIN photodetector 2 (10) is connected to the digital control system (1).

2. The laser ranging and echo detection system based on photonic transistors according to claim 1, characterized in that, The laser emitting device (2) uses an Nd:YAG pulsed laser with a wavelength of 1064nm.

3. The laser ranging and echo detection system based on photonic transistors according to claim 1, characterized in that, The emission optical system (3) consists of a beam expander (301) and a beam splitter (302). After the emitted laser pulse passes through the emission optical system (3), it is expanded and split, and then enters the PIN photodetector 1 (4) and the target object (11) to be tested, respectively.

4. The laser ranging and echo detection system based on photonic transistors according to claim 1, characterized in that, The receiving optical system (6) consists of a receiving lens (601) and a narrowband filter (602); after the echo laser pulse passes through the receiving optical system (6), it enters the photonic transistor (8) as pump light.

5. The laser ranging and echo detection system based on photonic transistors according to claim 4, characterized in that, The photonic transistor (8) exhibits reflective properties to the source signal light emitted by the echo detection system light source (9) without pump light, meaning that no photons can pass through the photonic transistor (8) and be received by the PIN photodetector 2 (10). The photonic transistor (8) exhibits transmissive and amplified properties to the source signal light emitted by the echo detection system light source (9) with pump light, meaning that photons can pass through the photonic transistor (8) and be received by the PIN photodetector 2 (10).

6. The laser ranging and echo detection system based on photonic transistors according to claim 1, characterized in that, The photonic transistor (8) structure includes: a nanowire (12), a low-loss dielectric waveguide (13), and a single-photon emitter (14); the nanowire (12) is made of silver material with a dielectric constant ε≈-50+0.6i, with a subwavelength cylindrical structure at the end and an hourglass-shaped structure with a gradually decreasing radius in the middle part; the low-loss dielectric waveguide (13) is made of a material with a dielectric constant ε=2 and is partially coupled to the nanowire (12); the single-photon emitter (14) is a CdSe / ZnS quantum dot, a CdSe / CdS quantum dot, a ZnCdSe / ZnS quantum dot, or a perovskite quantum dot.

7. The laser ranging and echo detection system based on photonic transistors according to claim 6, characterized in that, The pump light input port of the photonic transistor (8) is a port of the low-loss dielectric waveguide (13); the source signal light input port of the photonic transistor (8) is at the single photon emitter (14).

8. A laser ranging echo detection method based on photonic transistors, the specific steps of which are as follows: S1. Connect the digital control system (1) and the laser emitting device (2) in sequence. The laser emitting device (2) generates laser pulses, which are then split by the emitting optical system (3). S2. In step S1, a portion of the laser pulse signal split into the PIN photodetector 1 (4) is then amplified by the main wave amplifier (5) and the start timing signal is transmitted to the digital control system (1) to record the laser pulse emission time t1. S3. The laser pulse signal split in step S1 is directed towards the target object (11) and diffusely reflected by the target object (11). The subsequent echo laser pulse is then used as the pump light of the photonic transistor (8) to control the start of the photonic transistor (8) after passing through the receiving optical system (6) and the reflector (7). The echo detection system light source (9) provides the source signal light for the photonic transistor (8). S4. Upon receiving the echo laser pulse, the photonic transistor (8) exhibits transmission and gain. The source signal light is transmitted through the photonic transistor (8) and detected by the PIN photodetector 2 (10). As the end timing signal, it is finally transmitted to the digital control system (1) to complete the detection of the distance to the target object.

9. The laser ranging echo detection method based on photonic transistors according to claim 8, characterized in that, In step S4, the specific details are as follows: Record the echo laser pulse time t2, calculate the time interval t = t1 - t2 between the emitted laser pulse and the echo laser pulse, and calculate the distance D of the target object using the formula D = c * t / 2. Where c represents the speed of light.

10. The laser ranging echo detection method based on photonic transistors according to claim 8, characterized in that, The process of using the photonic transistor (8) to achieve laser ranging echo detection is as follows: The echo laser pulse is received by the receiving optical system (6) and the reflector (7) and is introduced into the pump light inlet of the photonic transistor (8). The photon enters the low-loss dielectric waveguide (13). The photon is transmitted to the coupling point between the low-loss dielectric waveguide (13) and the nanowire (12) and is transferred to the nanowire (12). Surface plasmon polaritons are excited on the nanowire (12). The strong interaction between the surface plasmon polaritons and the single-photon emitter (14) causes a change in the energy level of the single-photon emitter (14). The single-photon emitter (14) changes from reflecting the source signal light to transmitting and gaining. At this time, the source signal light emitted by the echo detection system light source (9) can be transmitted through the photonic transistor (8) to transmit the end-of-time signal. After the surface plasmon polaritons are excited on the nanowire (12), the light is transferred back to the low-loss dielectric waveguide (13).

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