A non-equilibrium optical pumping source with nanosecond to sub-nanosecond rise time and a method of operation

Abstract

This invention discloses a non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds and its operating method. This invention integrates a collimating mirror, a reflecting mirror, a beam splitter, a light-absorbing plate, a hemispherical mirror, an aperture, a converging lens, a high-speed motor, a turntable, and a diffuse reflection assembly to obtain a non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds. By reducing the spot size, increasing the rotation speed, and increasing the turntable diameter, the signal rise time can be compressed to the order of nanoseconds to sub-nanoseconds. This effectively solves the problem of inaccurate time constant measurement caused by the excessively long rise time of the output signal of traditional mechanical choppers when measuring the response time of fast infrared detectors using the frequency descent method, thus achieving high-precision measurement of the infrared detector time constant.

Description

Technical Field

[0001] This invention relates to a non-equilibrium optical pump source and its operating method with rise times on the order of nanoseconds to sub-nanoseconds. More specifically, it relates to a non-equilibrium optical pump source with rise and fall times on the order of nanoseconds to sub-nanoseconds by adjusting the size of the light spot diameter d, the radius R from the outer surface of the diffuse reflection component to the center of the turntable axis, and the angular velocity ω of the motor rotation. Background Technology

[0002] The response time of an infrared detector is one of its key parameters; therefore, accurate measurement of the response time of a photodetector is essential. [1] .

[0003] It has been reported that the time constant of thermal devices is typically on the order of milliseconds, while the time constant of optoelectronic devices is on the order of microseconds (photoconductive devices) or nanoseconds (photovoltaic devices). In recent years, however, the time constant of novel infrared photodetectors based on two-dimensional materials has typically ranged from microseconds to milliseconds. [2-3] When measuring response time using the frequency response method, a mechanical chopper is typically used to modulate the light. When an ideal rectangular pulse of light is applied to the detector, due to the detector's response delay, the output waveform is not an ideal rectangular wave, but rather a waveform with a certain rise and fall time. Traditional mechanical choppers use blades to modulate the light, and due to the size limitations of the blades, the modulated output also has rise and fall times. Especially for low-frequency modulation, the chopper output signal has a long rise and fall time, typically on the order of milliseconds to microseconds. Therefore, the measured detector response time may have a significant error. Currently, mechanically modulated optical pump sources with low rise and fall times are relatively rare.

[0004] References:

[0005] [1] Deng Shenggui, Yang Peisheng. Test of response time of silicon photodetector [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 TernaryTa2NiSe5, 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 purpose of this invention is to propose a non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds, so as to achieve accurate measurement of the response time of infrared detectors.

[0009] A non-equilibrium optical pump source structure with a rise time on the order of nanoseconds to sub-nanoseconds is described below:

[0010] Figure 1 This is a top view of the optical path structure, including a light source 1, a collimating mirror 2, a reflecting mirror 3, a beam splitter 4, a light-absorbing plate 5, a hemispherical mirror 6, an aperture 7, a converging lens 8, a turntable 9, a diffuse reflection assembly 10, a light absorption layer 11, and a high-speed motor 12. The light beam emitted by the light source 1 is collimated by the collimating mirror 2 and becomes parallel light. 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 light-absorbing plate 5. The transmitted light passes through the hemispherical mirror 6 and converges at the center of the sphere. An aperture 7 is placed outside the center of the sphere. The converging lens 8 converges the light from the aperture hole (i.e., the hole of the aperture 7) onto the outer surface of the turntable 9 to form a small diameter light spot. The exterior of the turntable 9 is composed of alternating diffuse reflection components 10 and light absorption layers 11. Specifically, the diffuse reflection components 10, with a diffuse reflection layer 10-3 on the exterior, are installed on the outside of the turntable 9. The diffuse reflection layer 10-3 on the exterior of the turntable 9 and the light absorption layer 11 on the exterior of the turntable 9 form an alternating structure of diffuse reflection and light absorption layers. When the light spot is focused on the diffuse reflection layer 10-3 on the exterior of the diffuse reflection components 10, it is out of focus on the light absorption layer 11, thus effectively shutting off the signal. Small-diameter light spots are reflected by the exterior of the diffuse reflection components 10, collected by the converging lens 8, and then pass through the aperture 7 and hemispherical lens 6 before returning to the beam splitter 4 for reflection 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 to 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 diffuse reflection component 10 has an inner recessed groove 10-1 on its inner side. The diffuse reflection component 10 is mounted on the turntable through the inner recessed 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 tilt angle, thereby effectively reducing the interference of cross-sectional reflection during the transition of the light spot from the outer surface of the diffuse reflection component 10 to the light absorption layer 11.

[0013] The present invention discloses a method for operating a non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds. Based on the aforementioned non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds, the specific operating method is as follows:

[0014] The diameter of the light spot illuminating the outer surface of the diffuse reflection component 10 (i.e., 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 angular velocity of the high-speed motor 12 is ω. The turntable 9 rotates under the drive of the high-speed motor 12. The width of the light pulse 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 width of the light pulse can be adjusted by adjusting the length of the diffuse reflection component 10. The time it takes 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 light pulse. The time it takes 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 light pulse. At a constant rotational speed, the rise time and fall time are equal. Therefore, pulsed light with rise and fall times on the order of nanoseconds to sub-nanoseconds can be obtained by adjusting the size of the spot diameter d, 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.

[0015] This patent integrates a collimating mirror, reflecting mirror, beam splitter, light-absorbing plate, hemispherical mirror, aperture, converging lens, high-speed motor, turntable, light-absorbing layer, and diffuse reflection component. By reducing the spot size, increasing the rotation speed, and increasing the distance from the outer surface of the diffuse reflection component to the turntable axis (i.e., the turntable diameter), a non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds can be obtained, thus compressing the signal rise time to the nanosecond to sub-nanosecond order. This effectively solves the problem of inaccurate time constant measurement caused by the excessively long rise time of traditional mechanical choppers when measuring the response time of fast infrared detectors using the frequency descent method, achieving high-precision measurement of the infrared detector time constant. Attached image description:

[0016] Figure 1 This is a top view of the optical path structure of the non-equilibrium optical pump source of the present invention, which has a rise time on the order of nanoseconds to sub-nanoseconds.

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

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

[0019] In the diagram: 1. Light source; 2. Collimating lens; 3. Reflecting mirror; 4. Beam splitter; 5. Light-absorbing plate; 6. Hemispherical mirror; 7. Aperture; 8. Converging lens; 9. Turntable; 10. Diffuse reflection assembly; 10-1. Concave groove; 10-2. Inclined surface; 10-3. Diffuse reflection layer; 11. Light absorption layer; 12. High-speed motor. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings.

[0021] According to the structure described in the above invention, an embodiment of a non-equilibrium pump source is fabricated.

[0022] Example 1:

[0023] like Figure 1 As shown, a non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds includes a light source, collimating mirror, reflecting mirror, beam splitter, light-absorbing plate, hemispherical mirror, aperture, converging lens, high-speed motor, turntable, light-absorbing layer, and diffuse reflection component. The light beam emitted by the light source 1 is collimated by the collimating mirror 2 to become parallel light. The reflecting mirror 3 reflects the parallel light onto the beam splitter 4. The light reflected by the beam splitter is absorbed by the light-absorbing plate 5. The transmitted light passes through the hemispherical mirror 6 and converges at the center of the sphere. An aperture 7 is placed outside the center of the sphere. The converging lens 8 focuses the light from the aperture onto the outer surface of the diffuse reflection component 10 mounted on the turntable 9, forming a small-diameter light spot. The outer surface of the turntable 9 is divided into four equal parts, alternately composed of the diffuse reflection component 10 and the light-absorbing layer 11. The small-diameter light spot is reflected by the outer surface of the diffuse reflection component 10, and the light is collected by the converging lens 8, passes through the aperture 7 and the hemispherical lens 6, and returns to the beam splitter 4 for reflection and output.

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

[0025] As described above, the non-equilibrium optical pump source structure of the present invention, with a rise time on the order of nanoseconds to sub-nanoseconds, is clear and highly practical, and has good application value in the accurate characterization of the time constant of infrared detectors.

[0026] The above examples are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person skilled in the art 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 skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds, characterized in that, The non-equilibrium optical pump source includes a light source (1), a collimating mirror (2), a reflecting mirror (3), a beam splitter (4), a light-absorbing plate (5), a hemispherical mirror (6), an aperture (7), a converging lens (8), a turntable (9), a diffuse reflection assembly (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 light-absorbing plate (5). The transmitted light is converged at the center of the hemispherical mirror (6). An aperture (7) is placed outside the center of the hemispherical mirror. The converging lens (8) converges the light from the aperture onto the outer surface of the turntable (9) to form a small diameter. Light spot; The diffuse reflection component (10) with a diffuse reflection layer (10-3) on the outer side of the turntable (9) is installed on the outside of the turntable (9). The diffuse reflection layer (10-3) on the outer side of the turntable (9) and the light absorption layer (11) on the outer side of the turntable (9) form an alternating structure of diffuse reflection and light absorption layer. When the light spot is in a focused state on the diffuse reflection layer (10-3) on the outer side of the diffuse reflection component (10), it is in a defocused state on the light absorption layer (11), thereby effectively turning off the signal. The small diameter light spot is reflected by the outer side of the diffuse reflection component (10) and then collected by the converging lens (8). The light passes through the aperture (7) and the hemispherical lens (6) and returns to the beam splitter (4) for reflection and output. By reducing the spot size, increasing the rotation speed, and increasing the distance from the outer surface of the diffuse reflection component to the center of the turntable, a non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds can be obtained.

2. The non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds according to claim 1, characterized in that, 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. A non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds, as described in claim 2, is characterized in that... The diffuse reflection component (10) has an inner groove (10-1) on the inside. The diffuse reflection component (10) is mounted on the turntable (9) through the inner 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 tilt angle of 45°~60°.

4. A method for operating a non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds, characterized in that, Based on the non-equilibrium optical pump source with a rise time on the order of nanoseconds to sub-nanoseconds as described in claim 1, 2, or 3, its operation method is as follows: The diameter of the light spot illuminating 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 angular velocity of the high-speed motor (12) is ω, and the turntable (9) rotates under the drive of the high-speed motor (12). The width of the light pulse is the time required for the light spot to sweep across the outer surface of the diffuse reflection component (10). The width of the light pulse is adjusted 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 diffuse reflection layer (10-3) is the rise time of the light pulse. The time it takes for the light spot to transition from the diffuse reflection layer (10-3) to the light absorption layer (11) is the falling edge time of the light pulse. At a constant rotation speed, the rise time and fall time are equal; 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), pulse light with a rise time and fall time on the order of sub-nanosecond or even nanosecond can be obtained.

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