Infrared detector absolute spectral responsivity calibration system and method based on optical microcavity

Abstract

The application discloses an absolute spectral responsivity calibration system and method of an infrared detector based on an optical microcavity, and the system comprises a pump light generating device, a first photon counting module capable of being switched in an optical path, an optical microcavity module, a background light elimination module, a tentative calibration infrared detector, a second photon counting module, a current measurement module and a control and data acquisition module. The application introduces the optical microcavity technology into the spectral responsivity calibration of the infrared detector based on the spontaneous parametric down-conversion calibration principle, solves the problem that the existing spontaneous parametric down-conversion calibration method can only be implemented at a single wavelength point or a narrow waveband, and realizes the absolute calibration of the wide waveband continuous spectral responsivity of the infrared detector.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical radiation measurement, and particularly relates to an absolute spectral responsivity calibration system for an infrared detector based on an optical microcavity and an absolute spectral responsivity calibration method for an infrared detector based on an optical microcavity. BACKGROUND

[0002] The absolute spectral responsivity calibration technology for an infrared detector is one of key technologies for quantitative infrared light information. At present, the traditional calibration methods for an infrared detector, as shown in the prior art, mainly have the following two characteristics: Figure 1

[0003] (1) A high-precision primary standard is needed. The primary standard based on a standard radiation source is a blackbody radiation source, and the primary standard based on a standard detector is an absolute cryogenic radiometer. Therefore, the calibration result of the infrared detector is directly affected by the measurement precision of the primary standard.

[0004] (2) A complete standard transfer link needs to be designed to complete the precision transfer of the primary standard. Since each stage of the transfer link introduces new uncertainty sources, the final combined uncertainty is increased. In addition, in the standard detector-based illuminance or luminance measurement method, the aperture size and solid angle size need to be precisely measured, which inevitably affects the precision of the calibration.

[0005] In general, the traditional optical radiation calibration methods based on a high-precision blackbody radiation source and a cryogenic radiometer need to establish a high-precision primary standard and a standard transfer chain. The transfer chain is long and has low precision. With the continuous development and maturity of China's space technology, the traditional optical radiation calibration method is limited by the radiation reference and the transfer link, and it is difficult to improve the calibration precision. Especially in the infrared band, due to the performance constraints of optoelectronic components, the calibration precision can only reach about 2%-7%, which is much lower than the calibration precision in the visible-near infrared band. Therefore, relevant researchers are also committed to developing a new calibration method and system to improve the calibration precision. If this method can reduce or eliminate the cumulative error introduced by the radiation reference and the transfer link process, and only replace the physical standard with objective physical effects to improve the reproducibility and precision of the reference, the method theoretically has higher calibration precision.

[0006] ​The new calibration method is parametric down-conversion calibration, which uses the correlated photons generated by spontaneous parametric down-conversion as the light source in calibration, and can accurately present at any time and space without relying on a certain standard device or a certain transfer process. The spontaneous parametric down-conversion process is the process that the emitted photons of the pump source are coupled with the second-order nonlinear medium to generate correlated photons, that is, each high-frequency pump photon spontaneously converts into a pair of low-frequency photons (signal light and idle light) with a certain probability; the pair of photons has strict correlation in terms of wavelength, polarization state, emission direction, photon rate and other characteristics, and thus is called "correlated photon pair" or "entangled photon pair". Therefore, the calibration method based on the spontaneous parametric down-conversion process provides an excellent means for "standard-free transfer" of radiation calibration.

[0007] However, the existing absolute spectral responsivity calibration methods of infrared detectors based on spontaneous parametric down-conversion are based on certain nonlinear optical crystals, and can realize frequency conversion from visible light to mid-infrared light. However, in order to excite the nonlinear effect of the crystal, there is a certain requirement for the pump light power, and the wavelength range of the laser that meets the requirement of the pump light power is limited, which limits the continuous spectral range of infrared calibration, and only a few fixed points or narrow spectral range can realize the absolute spectral responsivity calibration of infrared detectors. Specifically, the existing spectral responsivity calibration method of optical detectors based on spontaneous parametric down-conversion is mainly aimed at photon counting detectors, and the requirement for light flux is very low, and the absolute calibration of wideband continuous spectrum can be realized at low photon rate (<10 8 However, in the infrared band, most of the analog detectors are used in photoelectric measurement and remote sensing detection applications, and the output signal of the analog detector is photocurrent, which cannot be counted and time-coincidence measured, and the basic measurement method adopted by the photon counting detector cannot meet the needs of the calibration of the analog detector. The calibration of the analog infrared detector requires a high incident correlated photon rate, and under the existing conditions of infrared lasers and spontaneous parametric down-conversion technology, the spectral responsivity calibration of infrared detectors in a wideband continuous spectrum cannot be realized. SUMMARY

[0008] Therefore, it is necessary to provide an infrared detector absolute spectral responsivity calibration system based on an optical microcavity, which introduces the optical microcavity technology into the spectral responsivity calibration of infrared detectors, combines the characteristics of the large nonlinear coefficient of lithium niobate crystal, and uses the extremely low threshold nonlinear effect of the optical microcavity made of periodically poled lithium niobate to solve the demand for a high-speed wideband continuous spectrum correlated photon in the spectral responsivity calibration of optical detectors based on spontaneous parametric down-conversion, and the spectral responsivity calibration of infrared detectors in a wideband continuous spectrum can be realized.

[0009] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0010] The application provides an absolute spectral responsivity calibration system for an infrared detector based on an optical microcavity, comprising:

[0011] a pump light generating device for generating and emitting pump light in a visible light band;

[0012] a first photon counting module switchable in an optical path, for measuring the number of emitted photons of the pump light generating device;

[0013] an optical microcavity module for converting the incident pump light, emitting idle light in a visible light band and signal light in an infrared band;

[0014] a background light elimination module for eliminating background light interference of the idle light and the signal light;

[0015] an infrared detector for receiving the signal light after the background light is eliminated;

[0016] a second photon counting module for receiving the idle light after the background light is eliminated and measuring the number of received photons;

[0017] a current measurement module for measuring the current signals of the infrared detector and the second photon counting module;

[0018] and a control and data acquisition module for controlling the pump light generating device, the first photon counting module, the second photon counting module and the current measurement module, and acquiring data to obtain the spectral responsivity of the infrared detector.

[0019] Further schemes further comprise a plurality of lens optical elements, and the lens optical elements comprise:

[0020] a first lens group for collimating the pump light emitted by the pump light generating device;

[0021] an optical prism for coupling the collimated pump light to the optical microcavity module;

[0022] a second lens group for collimating the idle light and the signal light emitted by the optical microcavity module;

[0023] and a beam splitting prism for splitting the collimated idle light and signal light.

[0024] Further schemes, the surface of the first lens group is provided with an antireflection film in the visible light band.

[0025] Further schemes, the pump light generating device comprises a pump laser and a mirror, wherein the mirror is used for adjusting the optical path.

[0026] Further schemes, the mirror is a gold-coated mirror.

[0027] Further, the optical microcavity module comprises:

[0028] The optical microcavity is made of a periodically poled lithium niobate crystal doped with magnesium oxide.

[0029] A temperature control heating unit is arranged to adjust the temperature of the optical microcavity.

[0030] Further, the optical microcavity is disc-shaped, and the optical axis coincides with the symmetry axis of the optical microcavity.

[0031] Further, the surface smoothness of the optical microcavity is in the order of nanometers, the Q value is greater than 10 6 , the diameter is 5 mm, the thickness is 0.6 mm, and the edge curvature is 1.2 mm.

[0032] Further, the infrared detector and the second photon counting module are connected to the three-dimensional translation mechanism, and the positions of the infrared detector and the second photon counting module are adjusted by the three-dimensional translation mechanism to receive corresponding optical signals.

[0033] The present application further provides an absolute spectral responsivity calibration method for an infrared detector based on an optical microcavity, comprising the following steps:

[0034] According to the spectral range of the infrared detector to be calibrated, the wavelength and power of the pump light and the working temperature of the periodically poled lithium niobate crystal optical microcavity are obtained from the nonlinear optical theory.

[0035] The photon counting values at each wavelength point of the pump light are obtained.

[0036] The pump light is converted by the periodically poled lithium niobate crystal optical microcavity to emit idle light in the visible light band and signal light in the infrared light band.

[0037] The current values and photon counting values of the idle light and the signal light are obtained respectively.

[0038] The quantum efficiency of the infrared detector to be calibrated is obtained according to the measurement data, and the spectral responsivity calibration is completed according to the relationship between the power responsivity and the quantum efficiency of the infrared detector.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The present application introduces optical microcavity technology into the spectral responsivity calibration of infrared detectors, combines the characteristics of the large nonlinear coefficient of periodically poled lithium niobate crystal, and uses the nonlinear effect of the optical microcavity of the periodically poled lithium niobate crystal with extremely low threshold pumping light to solve the demand for high-speed wide-band continuous spectrum related photons in the spectral responsivity calibration of optical detectors based on spontaneous parametric down-conversion, so that the spectral responsivity calibration of infrared detectors under wide-band continuous spectrum can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A schematic diagram of a traditional infrared detector absolute spectral responsivity calibration transfer link is shown in Figure 1.

[0042] Figure 2 A preferred embodiment of the present application is an infrared detector absolute spectral responsivity calibration system based on optical microcavity.

[0043] Figure 3 A preferred embodiment of the present application is an infrared detector absolute spectral responsivity calibration system based on optical microcavity. Figure 2 A schematic diagram of the shape and polarization of the periodically poled lithium niobate crystal optical microcavity is shown in Figure 3.

[0044] Figure 4 A schematic diagram of the shape and polarization of the periodically poled lithium niobate crystal optical microcavity is shown in Figure 3. Figure 2 A schematic diagram of the light wave of the periodically poled lithium niobate crystal optical microcavity is shown in Figure 4.

[0045] In the figure: 1-pump laser, 2-mirror, 3-first photomultiplier tube, 4-first photon counter, 5-first lens group, 6-optical prism, 7-periodically poled lithium niobate crystal optical microcavity, 8-heating seat, 9-temperature controller, 10-second lens group, 11-dichroic prism, 12-optical chopper, 13-second photomultiplier tube, 14-infrared detector, 15-current meter, 16-second photon counter, 17-three-dimensional translation stage, 18-industrial computer. DETAILED DESCRIPTION

[0046] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only for the purpose of explaining the present application, and cannot be understood as limiting the present application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used in the specification of the present application herein are only for the purpose of describing the specific embodiments and are not intended to limit the present application.

[0048] A preferred embodiment of the present application shows an infrared detector absolute spectral responsivity calibration system based on optical microcavity, please combine Figure 2The calibration system comprises a pump light generating device, a first photon counting module, an optical microcavity module, a background light elimination module, an infrared detector, a second photon counting module, a current measurement module, a control and data acquisition module, and a plurality of lens optical elements (which can be adjusted according to the optical path, and the main functions include collimation, adjustment and light splitting).

[0049] Specifically, the pump light generating device in the embodiment comprises a pump laser 1 and a mirror 2. The pump laser 1 is used to generate pump light, and the pump laser 1 in the embodiment works in the visible light waveband. The mirror 2 is used to reflect and adjust the optical path of the pump light emitted by the pump laser 1. Since the strength and stability of gold film are better than those of other metals, the surface gold-coated mirror has very high reflectivity and is commonly used as an infrared mirror. Therefore, preferably, the mirror 2 in the embodiment is a surface gold-coated mirror.

[0050] The first photon counting module is composed of a first photomultiplier tube 3 and a first photon counter 4, and is used to measure the number of emitted photons of the pump laser 1 at any time. In addition, in the embodiment, the first photon counting module can be switched in the optical path, that is, when the number of emitted photons needs to be measured, the first photomultiplier tube 3 is switched into the optical path of the pump light, and the first photon counter 4 measures the number of photons received by the first photomultiplier tube 3; when no measurement is needed, the first photomultiplier tube 3 is switched so as not to be in the optical path of the pump light. It can be understood that the switching mode is not particularly limited and can use conventional techniques in the art, which will not be described in detail here.

[0051] The pump light reflected by the mirror 2 is collimated by the first lens group 5. In the embodiment, the surface of the first lens group 5 is coated with a visible light waveband anti-reflection film, thereby improving the transmission of the pump light. Then, the pump light is coupled into the optical microcavity module through the optical prism 6. Preferably, in the embodiment, the optical prism 6 is made of diamond, because the optical properties of diamond are stable, such as the refractive index, transmittance and other parameters, which will not change dramatically with temperature, humidity and time, which is conducive to use in high-precision measurement. In addition, the refractive index of diamond is high, which is conducive to coupling the pump light into the optical microcavity module.

[0052] The optical microcavity module is composed of a periodically poled lithium niobate crystal optical microcavity 7, a heating seat 8 and a temperature controller 9, wherein the periodically poled lithium niobate crystal optical microcavity 7 is installed on the heating seat 8, the temperature controller 9 is connected with the heating seat 8, the temperature of the heating seat 8 is controlled through the temperature controller 9, the temperature of the periodically poled lithium niobate crystal optical microcavity 7 is adjusted, and wavelength tuning is realized. The optical microcavity is an optical device capable of confining the optical field meeting the resonance condition in the cavity and continuously circulating transmission along the microcavity wall. Therefore, the energy density in the optical microcavity is extremely high, which is very beneficial to the study of the strong interaction between the optical field and the matter. Due to the great enhancement of the optical microcavity to the optical field density, it has very high quality factor and very small mode volume, and the photon lifetime in the cavity can be increased to nanosecond or even microsecond, thereby greatly reducing the threshold of nonlinear effect, and it is easy to realize nonlinear optical effect under very low power laser pumping. Therefore, the periodically poled lithium niobate crystal optical microcavity 7 is used as the core component of the present application, and preferably, the material is a periodically poled lithium niobate crystal doped with magnesium oxide. This is because in lithium niobate, doping MgO ions can effectively improve the optical damage threshold of the crystal (so that it is not easy to be damaged by laser), and the doping amount of magnesium oxide is preferably 5%±1% by mole, and more preferably, the mole fraction of magnesium oxide is 5%. Further, in the present embodiment, the periodically poled lithium niobate crystal optical microcavity 7 has a disc shape, and specifically, the surface smoothness is nanometer level, the Q value is 10 6 order of magnitude or more, and the diameter, thickness, edge curvature and other parameters can be adjusted according to actual needs. In the present embodiment, the recommended values are diameter 5mm, thickness 0.6mm and edge curvature 1.2mm, so that the optical microcavity can better produce nonlinear optical effects and generate higher power signal light and idle light. The periodically poled lithium niobate crystal used to make the optical microcavity is periodically polarized along the radial direction. In the present embodiment, the processing method of the periodically poled lithium niobate crystal optical microcavity is to cut the thick periodically poled lithium niobate wafer along the z-axis direction by diamond lathe, and precisely polish to form a disc shape with extremely high surface smoothness. The shape and polarization of the optical microcavity are shown in Figure 3 and Figure 4 . The optical axis of the periodically poled lithium niobate crystal optical microcavity 7 coincides with the symmetry axis of its shape, which provides convenience for temperature phase matching. On the other hand, the more the optical axis of the periodically poled lithium niobate crystal optical microcavity 7 coincides with the symmetry axis of the shape, the better the effect. In the present application, the principle of using the optical microcavity is that in the microcavity, the pump light field and the two parametric light fields (signal light and idle light) have triple resonance. In addition, the coupling state of the pump light field and the optical microcavity can be continuously changed, and the wavelength of the pump laser and the temperature of the microcavity can be changed to achieve continuous wavelength tuning of the infrared signal light.

[0053] The pump light is coupled into the optical microcavity 7 of the periodically poled lithium niobate crystal. Under the nonlinear optical effect of the periodically poled lithium niobate crystal and the whispering gallery mode transmission of the optical microcavity, the pump light and the noise signal of the optical microcavity are subjected to spontaneous parametric down-conversion, thereby generating idle light in the visible light band and signal light in the infrared band.

[0054] The emitted idle light and signal light enter the light splitting prism 11 under the action of the second lens group 10. The idle light and the signal light are separated by dispersion. In order to facilitate high-precision measurement, the material of the light splitting prism 11 in the embodiment is the same as that of the optical prism 6.

[0055] The background light elimination module is composed of an optical chopper 12, which is used to eliminate background light interference and improve the light signal precision of the separated idle light and signal light.

[0056] The second photon counting module is composed of a second photomultiplier tube 13 and a second photon counter 16. The second photomultiplier tube is used to receive the idle light emitted by the optical microcavity, and the second photon counter 16 is used to measure the output photon number of the second photomultiplier tube 13. Meanwhile, the infrared detector 14 receives the signal light emitted by the optical microcavity. In the embodiment, the second photomultiplier tube 13 and the infrared detector 14 are preferably arranged on the three-dimensional translation stage 17, so that the corresponding light signals can be accurately received by adjusting the positions of the second photomultiplier tube 13 and the infrared detector 14.

[0057] The current measurement module is composed of a galvanometer 15, which is used to measure the current signals of the infrared detector 14 and the second photomultiplier tube 13.

[0058] In addition, the control and data acquisition module in the calibration system in the embodiment is an industrial computer 18, which is installed with control and calibration software of various optoelectronic devices. Specifically, the industrial computer 18 controls and acquires data of the pump laser 1, the first photon counter 4, the galvanometer 15, the second photon counter 16, and the three-dimensional translation stage 17. The software installed in the industrial computer 18 includes: pump laser control software, three-dimensional translation stage control software, photon counting software, current signal acquisition software, and spontaneous parametric down-conversion calibration software.

[0059] The functions that can be realized by these software include:

[0060] ① Setting the working wavelength and power of the output light of the pump laser 1;

[0061] ② Controlling the working states of the first photon counter 4, the galvanometer 15, and the second photon counter 16, and acquiring the output signals of the first photomultiplier tube 3, the second photomultiplier tube 13, and the infrared detector 14 in real time;

[0062] The motion of the three-dimensional translation table 17 is controlled so that the second photomultiplier 13 and the infrared detector 14 can accurately receive the optical signal.

[0063] Further, the working process of the absolute spectral responsivity calibration system of the infrared detector based on the optical microcavity mentioned in the above embodiment is specifically as follows:

[0064] The light emitted by the visible light band pump laser 1 is reflected by the mirror 2 and enters the first photomultiplier 3, and the first photomultiplier 3 obtains the number of pump photons through the first photon counter 4 and is switched out of the optical path; at this time, the pump light reflected by the mirror 2 is converged at the junction of the optical prism 6 and the periodically poled lithium niobate crystal optical microcavity 7 through the first lens group 5, and is coupled into the periodically poled lithium niobate crystal optical microcavity 7 through the optical prism 6; under the nonlinear optical effect of the periodically poled lithium niobate crystal and the whispering gallery mode transmission of the optical microcavity, the pump light and the noise signal of the optical microcavity occur spontaneous parametric down-conversion, generating idle light in the visible light band and signal light in the infrared band; the emitted idle light and signal light enter the beam splitter prism 11 under the action of the second lens group 10; the beam splitter prism 11 separates the idle light and the signal light by a certain angle through dispersion, and after passing through the optical chopper 12, the idle light and the signal light are incident to the second photomultiplier 13 and the infrared detector 14, respectively; finally, the output currents of the infrared detector 14 and the second photomultiplier 13 are measured by the galvanometer 15, the output photon number of the second photomultiplier 13 is measured by the second photon counter 16, and the spectral responsivity of the infrared detector is obtained by the spontaneous parametric down-conversion calibration software in the industrial computer 18. In the working process of the system, the wavelength of the pump laser 1 and the temperature of the periodically poled lithium niobate crystal optical microcavity 7 on the heating seat 8 can be changed by using the temperature controller 9, so as to realize the absolute spectral responsivity calibration of the infrared detector under a wide-band continuous spectrum.

[0065] On the basis of the above calibration system, the present application also proposes an absolute spectral responsivity calibration method of an infrared detector based on an optical microcavity, which comprises the following steps:

[0066] According to the spectral range of the infrared detector to be calibrated, the wavelength and power of the pump light and the working temperature of the periodically poled lithium niobate crystal optical microcavity are obtained from the nonlinear optical theory;

[0067] The photon counting values of the pump light at each wavelength point are obtained;

[0068] The pump light is converted by the periodically poled lithium niobate crystal optical microcavity to emit idle light in the visible light band and signal light in the infrared band;

[0069] The current value and the photon counting value of the idle light and the signal light are obtained, respectively;

[0070] The quantum efficiency of the infrared detector to be calibrated is obtained according to the measured data, and the spectral responsivity is calibrated according to the relationship between the power responsivity and the quantum efficiency of the infrared detector.

[0071] The method for calibrating the absolute spectral responsivity of the infrared detector according to the calibration system in the embodiment will be described below.

[0072] S1. According to the spectral range of the infrared detector 14 to be calibrated, the wavelength and power of the pump laser 1 and the working temperature of the periodically poled lithium niobate optical microcavity 7 are calculated according to the nonlinear optical theory;

[0073] S2. According to the calculation results, the wavelength and power of the pump laser 1 and the working temperature of the periodically poled lithium niobate optical microcavity 7 are set by using the wavelength control software of the pump laser 1 and the adjustment knob of the temperature controller 9 installed on the industrial computer 18;

[0074] S3. The power of the entire calibration system is turned on, and the photon count value of the pump laser 1 at each wavelength point is obtained by using the first photomultiplier tube 3, and then the first photomultiplier tube 3 is switched out of the optical path;

[0075] S4. The positions of the second photomultiplier tube 13 and the infrared detector 14 are adjusted by the three-dimensional translation stage 17, and the distance between the optical prism 6 and the periodically poled lithium niobate optical microcavity 7 is continuously fine-adjusted, and when the readings of the galvanometer 15 and the second photon counter 16 are maximum, the adjustment is stopped;

[0076] S5. The output current value of the galvanometer 15 and the photon count value of the second photomultiplier tube 13 of the second photon counter 16 are obtained;

[0077] S6. The measured data are imported into the spontaneous parametric down-conversion calibration software installed on the industrial computer 18, and the spectral power responsivity of the infrared detector 14 is obtained.

[0078] Specifically, the calculation method of the spontaneous parametric down-conversion calibration value is as follows:

[0079] The quantum efficiency of the infrared detector 14 to be calibrated can be expressed as:

[0080]

[0081] wherein, <δI i (t)δI s (t+τ)><δI i (t)δI s (t+τ)> is the photocurrent cross-correlation function measured by the galvanometer 15 of the second photomultiplier tube 13 and the infrared detector 14, <δI i(t) <delta>I i (t+tau) <delta>I i (t) <delta>I i (t+tau) is the autocorrelation function of the photocurrent output by the second photomultiplier 13, <Q i > and <Q s > are the average values of the charges directly measured by the second photon counter 16 and calculated by the infrared detector 14, respectively.

[0082] In the above formula, where q i and q s are the amounts of charges contained in each photoelectric pulse in the second photomultiplier 13 and the infrared detector 14, respectively, and T is the signal acquisition time of the first photomultiplier 3, the second photomultiplier 13 and the infrared detector 14. is the number of incident photons of the pump laser 1 obtained by the first photon counter 4.

[0083] After the quantum efficiency of the infrared detector 14 to be calibrated is obtained by the above formula, the spectral responsivity calibration can be completed according to the relationship between the power responsivity and the quantum efficiency of the detector of this type.

[0084] Compared with the existing spontaneous parametric down-conversion calibration method which can only be implemented at a single wavelength point or a narrow waveband, the present application innovatively proposes to use a periodically poled lithium niobate crystal optical microcavity to realize the absolute calibration of the wide waveband continuous spectral responsivity of an infrared detector based on the spontaneous parametric down-conversion calibration principle.

[0085] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, but as long as the combinations of the technical features do not contradict each other, they should be considered as within the scope of the present disclosure.

[0086] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An absolute spectral responsivity calibration system for an optical microcavity-based infrared detector, comprising: The application relates to a method for calibrating the spectral responsivity of an infrared detector. The application comprises: a pump light generating device for generating and emitting pump light in the visible light band; a first photon counting module switchable in the light path for measuring the emitted photon number of the pump light generating device; an optical microcavity module for converting incident pump light and emitting idle light in the visible light band and signal light in the infrared band; a background light elimination module for eliminating background light interference of the idle light and the signal light; an infrared detector for receiving the signal light after the background light is eliminated; a second photon counting module for receiving the idle light after the background light is eliminated and measuring the received photon number; a current measurement module for measuring the current signal of the infrared detector and the second photon counting module; and a control and data acquisition module for controlling the pump light generating device, the first photon counting module, the second photon counting module and the current measurement module and acquiring data to obtain the spectral responsivity of the infrared detector; wherein the optical microcavity module comprises: an optical microcavity made of a periodically poled lithium niobate crystal doped with magnesium oxide, wherein the optical microcavity is in the shape of a disc and the optical axis coincides with the symmetry axis of the optical microcavity; 2. The absolute spectral responsivity calibration system for an optical microcavity-based infrared detector according to claim 1, wherein, and a temperature control heating unit for adjusting the temperature of the optical microcavity. The application further comprises a plurality of lens optical elements, which comprise: a first lens group for collimating the pump light emitted by the pump light generating device; an optical prism for coupling the collimated pump light to the optical microcavity module; a second lens group for collimating the idle light and the signal light emitted by the optical microcavity module; 3. The absolute spectral responsivity calibration system for an optical microcavity-based infrared detector according to claim 2, wherein, and a beam splitting prism for splitting the collimated idle light and signal light.

4. The absolute spectral responsivity calibration system for an optical microcavity-based infrared detector of claim 1, wherein, The surface of the first lens group is provided with an antireflection film in the visible light band.

5. The absolute spectral responsivity calibration system for an optical microcavity-based infrared detector according to claim 4, wherein, The pump light generating device comprises a pump laser and a mirror, wherein the mirror is used for adjusting the light path.

6. The absolute spectral responsivity calibration system for an optical microcavity-based infrared detector of claim 1, wherein, The surface smoothness of the optical microcavity is in nanometer order, and the Q value is 10 6 The diameter is 5mm, the thickness is 0.6mm, and the edge curvature is 1.2mm.

7. The absolute spectral responsivity calibration system for an optical microcavity-based infrared detector of claim 1, wherein, The mirror is a gold-coated mirror.

8. A method for calibrating the absolute spectral responsivity of an optical microcavity-based infrared detector, characterized in that, The application further comprises a three-dimensional translation mechanism, wherein the infrared detector and the second photon counting module are respectively connected to the three-dimensional translation mechanism, the positions of the infrared detector and the second photon counting module are adjusted by the three-dimensional translation mechanism, and corresponding light signals are received. The application comprises the following steps: according to the spectral range of the infrared detector to be calibrated, the wavelength and power of the pump light and the working temperature of the periodically poled lithium niobate crystal optical microcavity are obtained according to the nonlinear optical theory; the photon counting values of the pump light at each wavelength point are obtained; the pump light is converted by the periodically poled lithium niobate crystal optical microcavity, and idle light in the visible light band and signal light in the infrared band are emitted; the current values and photon counting values of the idle light and the signal light are respectively obtained; the quantum efficiency of the infrared detector to be calibrated is obtained according to the measured data, and the spectral responsivity calibration is completed according to the relationship between the power responsivity and the quantum efficiency of the infrared detector.

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