Non-equilibrium optical pumping source with nanosecond-to-subnanosecond-magnitude rising edge time and working method

Abstract

The invention discloses a non-equilibrium optical pumping source with nanosecond-to-subnanosecond-magnitude rising edge time and a working method of the non-equilibrium optical pumping source. The non-equilibrium optical pumping source with nanosecond-to-subnanosecond-magnitude rising edge time is obtained by integrating devices such as a collimating mirror, a reflecting mirror, a beam splitter, a light absorption plate, a hemispherical mirror, a diaphragm, a converging lens, a high-speed motor, a turntable and a diffuse reflection assembly. The signal rising edge time can be compressed to nanosecond to subnanosecond magnitude by reducing the size of a light spot, increasing the rotating speed and increasing the diameter of a turntable, so that the problem that when the response time of a high-speed infrared detector is measured by using a frequency descent method, the signal rising edge time cannot be compressed is effectively solved. The problem of inaccurate time constant measurement caused by overlong rising edge time of output signals of a traditional mechanical chopper is solved, and high-precision measurement of the time constant of the infrared detector is realized.

Description

Technical Field

[0001] The present invention relates to a non-equilibrium optical pump source with a rise time in the nanosecond to sub-nanosecond range and a working method. More specifically, it relates to a non-equilibrium optical pump source that achieves a rise time and a fall time in the nanosecond to sub-nanosecond range by adjusting the size of the spot diameter d, the radius R from the outer surface of the diffuse reflection component to the axis of the turntable, and the angular velocity ω of the motor rotation. Background Art

[0002] The response time of an infrared detector is one of the main parameters of the detector. Therefore, it is necessary to accurately measure the response time of the photodetector. [1] 。

[0003] It is reported that the time constant of thermal-sensitive devices is usually in the millisecond range, and the time constant of optoelectronic devices is in the microsecond (photoconductive devices) or nanosecond (photovoltaic devices) range. In recent years, the time constant of new infrared photodetectors based on two-dimensional materials is usually in the microsecond to millisecond range. [2-3] When measuring the response time by the frequency response method, a mechanical chopper is usually used to modulate the light. When an ideal rectangular pulse light is given to the detector, due to the response delay of the detector, its output waveform is not an ideal rectangular wave, but a waveform with a certain rise edge and fall edge. The traditional mechanical chopper uses blades to modulate the light. Due to the volume limitation of the blades, the modulation output also has a rise edge and a fall edge. Especially for low-frequency modulation, the chopper output signal has a long rise time and fall time, usually in the millisecond to microsecond range. Therefore, there may be a large error in the measured detector response time. Currently, mechanical modulation type optical pump sources with low rise and fall times are relatively rare.

[0004] References:

[0005] [1] Deng Shenggui, Yang Peisheng. Measurement of the Response Time of Silicon Photodetectors [J]. Physics, 1981, 10(9).

[0006] [2] Ma Wanli, Wu Tuntan, Mao Wangchen, Qiu Qinxi, Li Jingbo, Jiang Lin, et al., Detection of Long Wavelength Photons via Quasi-Two-Dimensional Ternary Ta2NiSe5, ACS Applied Electronic Materials, 2022, 4(6): 2979-2986.

[0007] [3]Qiu Qinxi, Huang Zhiming, Photodetectors of 2D Materials from Ultraviolet to Terahertz Waves, Advanced Materials, 2021, 33(15): 2008126. Summary of the Invention

[0008] The object of the present invention is to propose a non-equilibrium optical pumping source with a rise time in the order of nanoseconds to sub-nanoseconds to achieve accurate measurement of the response time of an infrared detector.

[0009] The structure of a non-equilibrium optical pumping source with a rise time in the order of nanoseconds to sub-nanoseconds is described as follows:

[0010] Figure 1 As shown in the top view of the optical path structure, it includes a light source 1, a collimating mirror 2, a reflecting mirror 3, a beam splitter 4, an absorbing plate 5, a hemispherical mirror 6, a diaphragm 7, a converging lens 8, a turntable 9, a diffuse reflection component 10, a light absorption layer 11, and a high-speed motor 12. The light beam emitted by the light source 1 becomes parallel light after being collimated by the collimating mirror 2. The reflecting mirror 3 reflects the parallel light onto the beam splitter 4. The light reflected by the beam splitter 4 is absorbed by the absorbing plate 5, and the transmitted light is converged at the center of the sphere by the hemispherical mirror 6. A diaphragm 7 is placed outside the center of the sphere. The converging lens 8 converges the light rays from the diaphragm hole (i.e., the hole of the diaphragm 7) on the outer surface of the turntable 9 to form a small-diameter light spot. The outer surface of the turntable 9 is alternately composed of a diffuse reflection component 10 and a light absorption layer 11, that is, the diffuse reflection component 10 with a diffuse reflection layer 10-3 on the outer surface is installed outside the turntable 9, and the diffuse reflection layer 10-3 on the outer surface of the diffuse reflection component 10 on the outer surface of the turntable 9 and the light absorption layer 11 on the outer surface of the turntable 9 form an alternating structure of a diffuse reflection-light absorption layer. When the light spot is in a focused state on the diffuse reflection layer 10-3 on the outer surface of the diffuse reflection component 10, it is in an out-of-focus state on the light absorption layer 11, thereby effectively turning off the signal. The small-diameter light spot is reflected by the outer surface of the diffuse reflection component 10 and then collected by the converging lens 8. The light rays pass through the diaphragm 7 and the hemispherical lens 6 and return to irradiate the beam splitter 4 and are reflected and output.

[0011] Furthermore, there is a certain height difference between the diffuse reflection layer 10-3 and the light absorption layer 11, that is, there is a height difference of 50-100 μm between the diffuse reflection layer 10-3 and the light absorption layer 11, and the height of the diffuse reflection layer is higher than the height of the light absorption layer.

[0012] Furthermore, the inner side of the diffuse reflection component 10 is an inner concave groove 10-1. The diffuse reflection component 10 is installed on the turntable through the inner concave groove 10-1. At the same time, the cross-sections on both sides of the diffuse reflection component 10 are designed as inclined surfaces 10-2 with a certain inward inclination angle, thereby effectively reducing the interference of cross-section reflection during the process of the light spot transitioning from the outer surface of the diffuse reflection component 10 to the light absorption layer 11.

[0013] In the present invention, a working method of a non-equilibrium optical pumping source with a rise time in the nanosecond to sub-nanosecond range is based on the above-mentioned non-equilibrium optical pumping source with a rise time in the nanosecond to sub-nanosecond range. The specific working method is as follows:

[0014] The diameter of the light spot irradiated on the outer surface of the diffuse reflection component 10 (i.e., on the diffuse reflection layer 10-3) is d, the radius from the outer surface of the diffuse reflection component 10 to the axis of the turntable 9 is R, and the rotational angular velocity of the high-speed motor 12 is ω. The turntable 9 rotates driven by the high-speed motor 12. The optical pulse width is the time required for the light spot to sweep across the diffuse reflection layer 10-3 (i.e., the outer surface of the diffuse reflection component 10). Therefore, the adjustment of the optical pulse width can be achieved by adjusting the length of the diffuse reflection component 10. The time taken for the light spot to transition from the light absorption layer 11 to the outer surface of the diffuse reflection component 10 (i.e., the diffuse reflection layer 10-3) is the rise time of the optical pulse. The time taken for the light spot to transition from the diffuse reflection layer 10-3 to the light absorption layer 11 is the fall time of the optical pulse. At a constant rotational speed, the rise time is equal to the fall time. Therefore, by adjusting the size of the light spot diameter d, the size of the radius R from the outer surface of the diffuse reflection component 10 to the axis of the turntable 9 (which can be changed by changing the radius of the turntable 9), and the rotational angular velocity ω of the high-speed motor 12, pulsed light with a rise time and a fall time in the nanosecond to sub-nanosecond range can be obtained.

[0015] This patent integrates devices such as a collimating mirror, a reflecting mirror, a beam splitter, an absorbing plate, a hemispherical mirror, a diaphragm, a converging lens, a high-speed motor, a turntable, a light absorption layer, and a diffuse reflection component. By reducing the light spot size, increasing the rotational speed, and increasing the distance from the outer surface of the diffuse reflection component to the axis of the turntable (i.e., the turntable diameter), a non-equilibrium optical pumping source with a rise time in the nanosecond to sub-nanosecond range can be obtained, that is, the signal rise time can be compressed to the nanosecond to sub-nanosecond range. Thus, it effectively solves the problem of inaccurate measurement of the time constant due to the too long rise time of the traditional mechanical chopper when measuring the response time of an infrared detector with a relatively fast speed using the frequency decrease method, and realizes the high-precision measurement of the time constant of the infrared detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a top view of the optical path structure diagram of the non-equilibrium optical pumping source with a rise time in the nanosecond to sub-nanosecond range of the present invention.

[0017] Figure 2 It is a three-dimensional structure diagram of the high-speed motor, the turntable, and the diffuse reflection component of the present invention.

[0018] Figure 3 It is a three-dimensional schematic diagram of the diffuse reflection component of the present invention.

[0019] In the figure: 1. Light source; 2. Collimating mirror; 3. Reflecting mirror; 4. Beam splitter; 5. Absorbing plate; 6. Hemispherical mirror; 7. Diaphragm; 8. Converging lens; 9. Turntable; 10. Diffuse reflection component; 10-1. Concave groove; 10-2. Inclined plane; 10-3. Diffuse reflection layer; 11. Light absorption layer; 12. High-speed motor. Specific embodiments

[0020] To make the objectives, technical solutions and advantages of the present invention clearer, the following describes the technical solutions of the exemplary embodiments of the present invention with reference to the accompanying drawings.

[0021] According to the structure in the above-mentioned invention content, one embodiment of a non-equilibrium state pump light source is fabricated.

[0022] Embodiment 1:

[0023] As Figure 1 shown, a non-equilibrium state optical pump light source with a rise time in the order of nanoseconds to sub-nanoseconds includes a light source, a collimating mirror, a reflecting mirror, a beam splitter, an absorbing plate, a hemispherical mirror, a diaphragm, a converging lens, a high-speed motor, a turntable, a light absorption layer, a diffuse reflection component, etc. The light beam emitted by the light source 1 becomes a parallel light after being collimated by the collimating mirror 2. The reflecting mirror 3 reflects the parallel light onto the beam splitter 4. The light reflected by the beam splitter is absorbed by the absorbing plate 5. The transmitted light is converged at the center of the sphere by the hemispherical mirror 6. A diaphragm 7 is placed outside the center of the sphere. The converging lens 8 converges the light rays from the diaphragm hole on the outer facade of the diffuse reflection component 10 mounted on the turntable 9 to form a small-diameter light spot. The outer facade of the turntable 9 is divided into four equal parts, which are alternately composed of the diffuse reflection component 10 and the light absorption layer 11. The small-diameter light spot is reflected by the outer facade of the diffuse reflection component 10, and the light rays are collected by the converging lens 8, pass through the diaphragm 7 and the hemispherical lens 6, and then return to irradiate the beam splitter 4 and are reflected and output.

[0024] For red light with a wavelength of 800 nm, the light spot diameter d = 1 μm, the radius from the outer facade of the diffuse reflection component 10 to the axis of the turntable is R = 10 cm, and the rotational speed of the high-speed motor is 100 r / s, that is, the angular velocity of the turntable ω = 200π rad / s. Therefore, the rise time The optical pulse width in this case is If the rotational speed of the high-speed motor is increased to 200 r / s, that is, the angular velocity of the turntable ω = 400π rad / s, and the radius of the turntable is increased so that the radius R from the outer facade of the diffuse reflection component 10 to the axis of the turntable is increased to R = 20 cm, then the rise time of the output optical pulse will be shortened to For red light with a wavelength of 400 nm, the light spot diameter d = 500 nm, the rotational speed of the high-speed motor is 250 r / s, that is, the angular velocity of the turntable ω = 500π rad / s, and the radius of the turntable is increased so that the radius R from the outer facade of the diffuse reflection component to the axis of the turntable is increased to R = 25 cm. At this time, the rise time

[0025] As described above, the non-equilibrium optical pump source structure of the present invention with a rise time in the nanosecond to sub-nanosecond range has a clear structure and strong practicability, and has good application value in aspects such as the accurate characterization of the time constant of infrared detectors.

[0026] The above examples are only illustrative of the principles and effects of the present invention, rather than limiting the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A non-equilibrium optical pump source with a rising edge time in the nanosecond to sub-nanosecond range, characterized in that, The non-equilibrium optical pumping source includes a light source (1), a collimating mirror (2), a reflecting mirror (3), a beam splitter (4), an absorbing plate (5), a hemispherical mirror (6), a diaphragm (7), a converging lens (8), a turntable (9), a diffuse reflection component (10), a light absorption layer (11), and a high-speed motor (12). The light beam emitted by the light source (1) becomes parallel light after being collimated by the collimating mirror (2). The reflecting mirror (3) reflects the parallel light onto the beam splitter (4). The light reflected by the beam splitter (4) is absorbed by the absorbing plate (5). The transmitted light converges at the center of the sphere through the hemispherical mirror (6). A diaphragm (7) is placed outside the center of the sphere. The converging lens (8) converges the light rays from the diaphragm hole on the outer surface of the turntable (9) to form a small-diameter light spot. The diffuse reflection component (10) with an outer surface being a diffuse reflection layer (10-3) is installed outside the turntable (9). The diffuse reflection layer (10-3) on the outer surface of the diffuse reflection component (10) of the outer surface of the turntable (9) and the light absorption layer (11) on the outer surface of the turntable (9) form an alternating structure of a diffuse reflection-light absorption layer. When the light spot is in a focused state on the diffuse reflection layer (10-3) on the outer surface of the diffuse reflection component (10), it is in an unfocused state on the light absorption layer (11), thereby effectively turning off the signal. The small-diameter light spot is reflected by the outer surface of the diffuse reflection component (10) and then collected by the converging lens (8). The light rays pass through the diaphragm (7) and the hemispherical lens (6) and return to irradiate the beam splitter (4) for reflection and output.

2. The non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds according to claim 1, wherein There is a height difference of 50 - 100 μm between the diffuse reflection layer (10-3) and the light absorption layer (11), and the height of the diffuse reflection layer is higher than that of the light absorption layer.

3. The non-equilibrium optical pump source with a rise time in the nanosecond to sub-nanosecond range according to claim 2, wherein The inner side of the diffuse reflection component (10) is an inward concave groove (10-1). The diffuse reflection component (10) is installed on the turntable (9) through the inward concave groove (10-1). At the same time, the cross-sections on both sides of the diffuse reflection component (10) are designed as inclined surfaces (10-2) with an inward inclination angle of 45° - 60°.

4. A working method of a non-equilibrium optical pumping source with a rising edge time in the nanosecond to sub-nanosecond range, characterized in that, Based on the non-equilibrium optical pumping source with a rise time in the order of nanoseconds to sub-nanoseconds described in claim 1 or 2 or 3, its working method is as follows: The spot diameter irradiated on the diffuse reflection component (10) is d, the radius from the outer surface of the diffuse reflection component (10) to the axis of the turntable (9) is R, the rotational angular velocity of the high-speed motor (12) is ω, the turntable (9) rotates driven by the high-speed motor (12), the optical pulse width is the time required for the spot to sweep across the outer surface of the diffuse reflection component (10), and the adjustment of the optical pulse width is achieved by adjusting the length of the diffuse reflection component (10). The time taken for the spot to transition from the light absorption layer (11) to the diffuse reflection layer (10-3) is the rise time of the optical pulse. The time taken for the spot to transition from the diffuse reflection layer (10-3) to the light absorption layer (11) is the fall time of the optical pulse. , at a constant rotational speed, the rise time is equal to the fall time; by adjusting the size of the spot diameter d, the size of the radius R from the outer surface of the diffuse reflection component (10) to the axis of the turntable (9), and the rotational angular velocity ω of the high-speed motor (12), pulsed light with a rise time and a fall time in the sub-nanosecond or even nanosecond range can be obtained.

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