CN116183536A - Mid-infrared up-conversion spectrum detection method of multi-wavelength pump - Google Patents
Mid-infrared up-conversion spectrum detection method of multi-wavelength pump Download PDFInfo
- Publication number
- CN116183536A CN116183536A CN202310164295.5A CN202310164295A CN116183536A CN 116183536 A CN116183536 A CN 116183536A CN 202310164295 A CN202310164295 A CN 202310164295A CN 116183536 A CN116183536 A CN 116183536A
- Authority
- CN
- China
- Prior art keywords
- infrared
- mid
- conversion
- spectrum
- wavelength
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 49
- 238000001831 conversion spectrum Methods 0.000 title claims abstract description 20
- 238000006243 chemical reaction Methods 0.000 claims abstract description 55
- 238000005086 pumping Methods 0.000 claims abstract description 36
- 238000001228 spectrum Methods 0.000 claims abstract description 35
- 238000002329 infrared spectrum Methods 0.000 claims abstract description 29
- 238000000034 method Methods 0.000 claims abstract description 28
- 239000013078 crystal Substances 0.000 claims abstract description 21
- 239000006185 dispersion Substances 0.000 claims description 8
- 238000000862 absorption spectrum Methods 0.000 claims description 6
- 230000009471 action Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- 230000001678 irradiating effect Effects 0.000 claims 1
- 238000005516 engineering process Methods 0.000 abstract description 15
- 239000000126 substance Substances 0.000 abstract description 6
- 238000012544 monitoring process Methods 0.000 abstract description 4
- 238000005259 measurement Methods 0.000 abstract description 3
- 238000010905 molecular spectroscopy Methods 0.000 abstract description 2
- 230000003595 spectral effect Effects 0.000 description 22
- 230000008569 process Effects 0.000 description 12
- 230000035945 sensitivity Effects 0.000 description 8
- 230000003287 optical effect Effects 0.000 description 6
- 238000013461 design Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 4
- 229910001634 calcium fluoride Inorganic materials 0.000 description 4
- 229910052732 germanium Inorganic materials 0.000 description 4
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 4
- 230000000737 periodic effect Effects 0.000 description 4
- 238000002310 reflectometry Methods 0.000 description 4
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000004476 mid-IR spectroscopy Methods 0.000 description 3
- 238000013459 approach Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 238000011896 sensitive detection Methods 0.000 description 2
- 238000010183 spectrum analysis Methods 0.000 description 2
- WSMQKESQZFQMFW-UHFFFAOYSA-N 5-methyl-pyrazole-3-carboxylic acid Chemical compound CC1=CC(C(O)=O)=NN1 WSMQKESQZFQMFW-UHFFFAOYSA-N 0.000 description 1
- 230000005457 Black-body radiation Effects 0.000 description 1
- 229910000661 Mercury cadmium telluride Inorganic materials 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- WPYVAWXEWQSOGY-UHFFFAOYSA-N indium antimonide Chemical compound [Sb]#[In] WPYVAWXEWQSOGY-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- WYOHGPUPVHHUGO-UHFFFAOYSA-K potassium;oxygen(2-);titanium(4+);phosphate Chemical compound [O-2].[K+].[Ti+4].[O-]P([O-])([O-])=O WYOHGPUPVHHUGO-UHFFFAOYSA-K 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000000844 transformation Methods 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000000411 transmission spectrum Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Photometry And Measurement Of Optical Pulse Characteristics (AREA)
- Spectrometry And Color Measurement (AREA)
Abstract
The invention discloses a mid-infrared up-conversion spectrum detection method of multi-wavelength pumping, which is characterized in that the method uses multi-wavelength narrow-band laser as a non-linear conversion pumping source, and simultaneously uses a multi-period quasi-phase matching crystal as a non-linear up-conversion medium, thereby realizing mid-infrared signal broadband and high-efficiency conversion, and finally obtaining mid-infrared spectrum detection with wide band, high resolution and ultrasensitivity by combining a high-performance near-infrared spectrum measurement and control element. Compared with the existing up-conversion spectrum technology, the method has the characteristics of large bandwidth and high efficiency, can high-fidelity and resolve the spectrum information of the middle infrared, provides an effective means for realizing the ultra-sensitive middle infrared spectrum measurement with wide band and high resolution, and is expected to be applied to important fields such as molecular spectroscopy, trace substance detection, infrared remote sensing, atmosphere monitoring and the like.
Description
Technical Field
The invention relates to the technical field of mid-infrared spectrum, in particular to a mid-infrared up-conversion spectrum detection method of multi-wavelength pumping.
Background
The mid-infrared band corresponds to the transition peaks of the vibration energy levels of a plurality of molecules, is directly related to the molecular components and structures of most biological tissues and chemical materials, is called a molecular fingerprint spectral region, and is widely applied to qualitative and quantitative detection of substances. The development of mid-infrared spectrum technology has important application prospect in life science, environmental monitoring, material engineering, medical diagnosis, infrared remote sensing and other aspects. In particular, the broadband mid-infrared spectrum technology is favorable for acquiring the spectral line characteristics of multiple components at one time, the high-resolution mid-infrared spectrum technology provides a powerful means for acquiring fine characterization of spectral lines, and the ultra-sensitive mid-infrared spectrum technology can acquire higher signal to noise ratio under the condition of low radiation illuminance. At present, mid-infrared spectrum technology is continuously changed and improved, and a novel mid-infrared spectrum detection technology with wide wave band, high resolution and ultra sensitivity is urgently developed so as to meet urgent demands of the scientific and industrial fields on the aspects of multi-component substance detection, high-precision spectral line analysis, trace substance detection and the like.
Currently, mid-infrared spectrometers are typically based on grating dispersion detection or using Fourier Transform Infrared (FTIR) detection. The grating spectrometer uses grating light splitting to spatially separate mid-infrared spectra, which are then detected by a linear array detector. However, due to the limited pixels of the mid-infrared array and the low frame rate, the resolution of the grating spectrometer is typically low and the spectral speed is slow. Although fourier transform infrared spectrometers can use single-point detectors to achieve higher spectral resolution and have a wider spectral range, they rely on mechanical scanning, which greatly limits the spectral velocity and are therefore unsuitable for rapid acquisition. In addition, the detection element of the mid-infrared spectrometer generally adopts a semiconductor material based on a narrow band gap (such as HgCdTe and InSb) and is limited by intrinsic noise, and dark current and thermal noise are usually suppressed by a multistage cooling system with extremely low temperature so as to improve the sensitivity of the detection system. Even so, the sensitivity is still far from that of a detector operating in the near infrared band. Therefore, mid-infrared spectrum technology is limited by a spectroscopic mode and an infrared detection device, and breakthrough is needed in the aspects of spectral speed, spectral resolution, detection sensitivity and the like.
In view of the difficulties faced by the current mid-infrared spectrum technology, mid-infrared frequency up-conversion detection technology has rapidly developed in recent years. The technology converts the weak middle infrared signal into the visible/near infrared band with high fidelity through the nonlinear sum frequency process, so that not only can a mature dispersion light-splitting element be utilized to obtain higher spectral resolution, but also a visible/near infrared detection array with more pixels, lower noise and higher response speed can be utilized to detect, and the ultra-sensitive and rapid spectrum formation of the middle infrared band is realized. However, the existing up-conversion spectrum technology is limited by quasi-phase matching bandwidth, so that the spectrum window for efficient conversion is generally only tens of nanometers, and far from meeting the requirements of broadband detection scenes such as infrared remote sensing, environment monitoring, astronomical observation and the like. The limitation of the matching bandwidth is broken through, and the matching bandwidth is widened by means of tuning the temperature of the nonlinear crystal, transforming the grating period of the nonlinear medium, tuning the incidence angle of the signal light and the like. However, these approaches rely on mechanical tuning, which is slow and severely limits the spectrum acquisition speed. In addition, another common method is to increase the bandwidth with a chirped nonlinear medium that varies continuously in period, which avoids tuning transformations, but the limited nonlinear range limits the conversion efficiency and thus sacrifices the detection sensitivity. Therefore, the up-conversion spectrum technology faces the mutual constraint of the detection bandwidth and the detection efficiency, and the development of a mid-infrared up-conversion spectrum detection technology with broadband conversion and high conversion efficiency is needed.
Disclosure of Invention
The invention aims to provide a mid-infrared up-conversion spectrum detection method of multi-wavelength pumping, which aims at the defects of the prior art, adopts corresponding quasi-phase matching period extremum under different pumping wavelengths, designs a multi-period nonlinear medium, widens the integral bandwidth of nonlinear phase matching under the action of multi-wavelength single-frequency narrow linewidth laser pumping, and realizes high-efficiency mid-infrared frequency up-conversion detection by utilizing the multi-wavelength single-frequency pumping and the multi-period nonlinear medium. Finally, the near infrared mature dispersion element and the single photon detection array are utilized to realize high-sensitivity, high-speed and high-resolution spectrum analysis in a broad spectrum range of the mid-infrared. The method overcomes the mutual restriction between the broad spectrum detection of the mid-infrared band and the high conversion efficiency, can realize the ultra-sensitive detection of the mid-infrared spectrum with wide band, high efficiency and high resolution, and provides powerful support for the applications of infrared molecular spectroscopy, trace substance detection, infrared remote sensing detection, atmosphere monitoring and the like.
The specific technical scheme for realizing the aim of the invention is as follows: the method is characterized in that a multi-wavelength single-frequency narrow-band laser is used as pump light, a multi-period nonlinear medium is used for realizing broadband mid-infrared coverage and efficient mid-infrared frequency up-conversion, converted spectrum components are not overlapped, and a high-performance near-infrared dispersion and detection element is used for realizing high-resolution and ultrasensitive detection of mid-infrared broadband spectrum, and the method specifically comprises the following steps:
1) The single-frequency narrow-linewidth laser with multiple wavelengths is used as the pumping light, the dilemma that the phase matching bandwidth is limited under the traditional single-wavelength pumping is broken through, the simultaneous high-efficiency conversion of a plurality of middle infrared signal bands can be realized by different pumping wavelengths, the converted spectrum components are not overlapped, and the wide-band middle infrared spectrum detection range can be obtained through simple up-conversion spectrum splicing.
2) The multi-period nonlinear medium is used as a medium for frequency up-conversion, the quasi-phase period extremum corresponding to nonlinear conversion under different pumping wavelength conditions is referred, the crystal or waveguide with the period being discretely changed is designed, the phase matching window of the broadband is obtained through the multi-period structure, meanwhile, the longer nonlinear interaction length is obtained, and the more efficient nonlinear frequency up-conversion is realized.
3) The pump light source adopts narrow-band single-frequency laser, and has the characteristics of single longitudinal mode, low noise and narrow frequency spectrum, so that the one-to-one correspondence between the wavelength after nonlinear conversion and the wavelength of the middle infrared signal can be ensured, the spectrum information of the middle infrared signal can be kept with high fidelity, and the high-resolution dispersive element and the multi-pixel detection element for visible light and near infrared are combined, so that the guarantee is provided for realizing high-resolution middle infrared spectrum analysis.
The multi-period nonlinear medium comprises a crystal, a waveguide and other structures, and the matching bandwidth of the middle infrared signal is widened by using non-collinear quasi-phase matching, and the materials of the nonlinear crystal and the waveguide comprise but are not limited to: periodically Poled Lithium Niobate (PPLN) crystals/waveguides, periodically poled potassium titanyl phosphate (PPKTP) crystals/waveguides, periodically Poled Lithium Tantalate (PPLT) crystals/waveguides, and the like; the multi-period should be selected with reference to the quasi-phase period extremum of up-conversion under different pump wavelengths to ensure coverage of the mid-infrared spectrum range required to be detected, and the period selection of the nonlinear medium includes but is not limited to 34.8 μm, 28.1 μm, 25.8 μm, 24.1 μm; the crystal and waveguide structural design of the nonlinear medium comprises but is not limited to: multi-cycle cascade arrangement, multi-cycle staggered arrangement, etc.
The multi-wavelength single-frequency narrow-linewidth laser is used as a pumping light source by adopting multi-wavelength beam combination, the pumping light source is composed of a plurality of single-frequency narrow-linewidth continuous lasers, the broadband mid-infrared spectrum information can be kept in the frequency mixing process, and the number of the pumping laser sources is not limited to 4; the pump light wavelength includes, but is not limited to: 1.55 μm, 1.35 μm, 1.20 μm, 1.10 μm, etc.
The visible light, near infrared high resolution dispersive elements include, but are not limited to, prisms, gratings, virtual imaging arrays, and the like.
The envelope of the multi-pixel detector element is not limited to the detector array such as CCD, EMCCD, CMOS, sCMOS.
Compared with the prior art, the invention has the following remarkable technical effects and progress:
1) The multi-wavelength continuous laser is used as the pumping light, up-conversion spectrums corresponding to different pumping wavelengths are not overlapped, and a broadband mid-infrared spectrum detection window can be obtained through band splicing treatment, so that the dilemma of limited phase matching bandwidth under the traditional single-wavelength pumping is broken through. Meanwhile, the pump light source adopts narrow-band single-frequency laser, and has the characteristics of single longitudinal mode, low noise and narrow frequency spectrum, so that the one-to-one correspondence between the wavelength after nonlinear conversion and the wavelength of the middle infrared signal can be ensured, the spectrum information of the middle infrared signal can be maintained with high fidelity, and the guarantee is provided for realizing high-resolution middle infrared spectrum analysis.
2) The multi-period nonlinear medium is used as a medium for frequency up-conversion, and the mid-infrared incident crystal can obtain a broadband phase matching window without tuning temperature, period and angle, so that the limit of mechanical tuning on spectral forming speed is avoided. Meanwhile, compared with a nonlinear medium with a chirp structure, a longer nonlinear interaction distance can be obtained, so that the efficiency of broadband nonlinear frequency up-conversion is improved.
3) The intermediate infrared signal is converted into near infrared through frequency up-conversion in a nonlinear medium, and the performance bottleneck of the existing intermediate infrared device is overcome by adopting a near infrared dispersion element and an ultra-sensitive detection array which are excellent in performance, economical and effective, so that higher spectral resolution, faster light splitting speed and higher detection sensitivity are realized.
Drawings
FIG. 1 is a schematic diagram of phase matching of three-wave nonlinearity sum frequency in a collinear case;
FIG. 2 is a graph of co-linear quasi-phase period Λ corresponding to each band of mid-infrared under different wavelength pumping conditions;
FIG. 3 is a graph showing the relationship between the mid-IR wavelength and the up-conversion efficiency in the extremum period of FIG. 2;
FIG. 4 is a graph showing the relationship between the near infrared band range and the intensity corresponding to the mid infrared band of FIG. 3 after frequency up-conversion;
fig. 5 is a schematic structural diagram of a spectrum sensing apparatus of embodiment 1.
Detailed Description
The invention adopts a multi-wavelength single-frequency narrow linewidth laser to pump multi-period nonlinear medium, wherein the related optical field satisfies the law of conservation of energy and momentum, and the frequency is omega p And a frequency omega s Annihilation of infrared signal photons in low energy of (2) to produce a frequency omega u Is a photon of the up-conversion of (a). During the frequency conversion, when the phase matching condition is satisfied,Δk＝k u -k s -k p when zero, there is maximum conversion efficiency. In order to overcome the technical difficulties, the invention adopts a quasi-phase matching technology with high flexibility, and compensates the mismatch of delta k by selecting a proper inversion period lambda through the design of the periodic distribution of the polarized crystal, thereby ensuring that the mid-infrared spectrums with different wavelengths can meet the phase matching condition, and further realizing the frequency conversion.
Referring to fig. 1, three waves of pump light, mid-infrared signal light and up-converted light are propagated in a collinear manner along the periodic line distribution direction of the nonlinear medium, and the phase mismatch amount in the sum frequency action process is represented by the following (a):
wherein,,
and a grating wave vector introduced for the nonlinear medium periodic structure. In the nonlinear medium manufacturing process, lambda i Can be flexibly adjusted, so that the design period of a specific nonlinear process can be easily satisfied with Λk=0, the quasi-phase matching effect is realized, and the direction of energy flow is always from fundamental wave to sum frequency wave.
Referring to FIG. 2, the second order nonlinear MgO-PPLN crystal and the pump wavelength are respectively
And->
As an example, the collinear quasi-phase period Λ to which the mid-infrared wavelength matches has the relationship shown in fig. 2, and canEach curve is found to have a periodic extreme point, and the extreme point position varies with the choice of pump wavelength.
Referring to fig. 3, if a nonlinear crystal is designed by selecting a domain period Λ near an extreme point corresponding to a single pump wavelength, the mid-infrared signal matching bandwidth under each pump wavelength condition can reach about hundred nanometers. Thus, by designing the crystal period Λ, the pump wavelength, and selecting the appropriate crystal material, it is possible to achieve a frequency up-conversion process that matches to a particular mid-infrared wavelength range.
Referring to fig. 4, after the mid-infrared band matched under each pumping condition is subjected to nonlinear frequency up-conversion, the spectra in the near infrared part are not overlapped. Therefore, mid-infrared spectrum information can be uniquely and reversely deduced according to the corresponding pumping conditions, and mid-infrared broadband spectrum can be obtained through simple spectrum calculation and splicing. Specifically, it is first necessary to obtain the up-converted spectral intensity distribution I one time u (λ u ) Segmenting according to each pumping condition, and the up-conversion spectral intensity distribution corresponding to different pumping wavelengths is as follows
Up-conversion spectrum by segmentation->
The conversion relation with frequency is obtained by the following formula (b) to obtain mid-IR spectrum intensity distribution of each segment>
Next, a mid-IR spectral intensity distribution of each segment is obtained
Then, the spectrum intensity in the mid-infrared full detection range is obtained through the following (c)Distribution I s (λ s )：
By the above method, the spectrum intensity distribution curve sigma (lambda s )I s (λ s ) And spectral intensity distribution curve I without sample s (λ s ) The two are divided to obtain a broadband mid-infrared absorption spectrum sigma (lambda) of the sample to be detected s )。
Referring to fig. 2, under the condition of multi-wavelength pumping, a multi-period nonlinear crystal is adopted, and meanwhile, high-efficiency conversion of a plurality of mid-infrared signal bands is obtained, so that the bandwidth of the mid-infrared high-efficiency conversion is effectively widened. Because the up-conversion spectrums are not overlapped in each period, the mid-infrared spectrum information of the broadband can be obtained by selecting corresponding pump light to perform wavelength conversion. This approach enables a wider phase matching bandwidth compared to single wavelength pumping versus single period crystal schemes. Compared with the traditional temperature, period and angle adjusting modes, the method for obtaining the broadband has the advantages that the complicated tuning process is omitted, and compared with the method for realizing wide spectrum conversion by using the chirp crystal with the period continuously changed, the method for obtaining the broadband has the advantage that the nonlinear interaction length is longer, so that the nonlinear conversion is realized more efficiently. The invention adopts a plurality of narrow-band single-frequency laser combinations, can obtain spectrum modes corresponding to mid-infrared one by one in a near-infrared band when interacting with a broadband infrared spectrum signal, thereby realizing high-fidelity infrared spectrum information transfer and providing guarantee for high-precision mid-infrared spectrum analysis.
The near infrared mature dispersion element and the ultra-sensitive single photon detection array adopted by the invention have more mature process and more excellent performance. Near infrared dispersive elements, such as gratings, have denser reticles and higher grating efficiencies than mid-infrared band dispersive elements. In addition, the near infrared detection array has the advantages of more pixels, lower noise and faster response speed compared with a middle infrared detector. Therefore, through the frequency up-conversion process, the mid-infrared signal is converted into the near-infrared band, so that the spectral analysis with higher spectral resolution, higher sensitivity and higher spectral speed can be realized.
The invention is further described in detail below with respect to a specific implementation of mid-infrared up-conversion spectral detection for multi-wavelength pumping.
Examples
Referring to fig. 5, a spectrum detecting apparatus embodying the present invention specifically includes: the device comprises a broadband mid-infrared light source 1, a germanium window plate 2, an off-axis parabolic mirror 3, a sample to be tested 4, a calcium fluoride lens 5, an a single-frequency continuous pumping laser 6, a b single-frequency continuous pumping laser 7, a c single-frequency continuous pumping laser 8, a d single-frequency continuous pumping laser 9, a wavelength division multiplexer 10, an achromatic focusing lens 11, a dichroic mirror 12, a multi-period cascade waveguide 13, a temperature control furnace 14, an a lens 16, a filter 16, a b lens 17, a near infrared grating 18, a metal mirror 19, a c lens 20, a COMS detection array 21 and a computer 22.
The broadband mid-infrared light source 1 can be an active light source generated by continuous spectrums such as a waveguide, a soft glass optical fiber and the like, or can be a passive light source such as a thermal light source and the like, and the wavelength range of the broadband mid-infrared light source can be covered by 3-5 mu m.
The germanium window sheet 2 is used for blocking any incident visible light, and is plated with a broadband antireflection film with average reflectivity of less than 3% within 3-5 mu m.
The off-axis parabolic mirror 3 is aimed at collecting infrared signals with an average reflectivity of more than 96% over a wide band of 800nm-20 μm.
The purpose of the sample 4 to be tested is to measure the absorption/transmission spectrum of the sample, the absorption degree of the sample to be tested to different wavelengths is different, and the experimental system can obtain the absorption rate of the sample to be tested to each wavelength by measuring the spectrum without and with the sample. The sample to be tested includes, but is not limited to: solid, gas, liquid, etc.
The purpose of the calcium fluoride lens 5 is to focus the mid-infrared carrying spectral information into a multi-period cascade waveguide 13.
The a, b, c, d single-frequency continuous pumping lasers 6, 7, 8 and 9 are external cavity diode lasers with tunable central wavelengths, and the central waves thereofRespectively of length of
And->
The spectrum width is 3KHz, the polarization contrast is more than 20dB, and the output power can reach 10W. The four lasers are used as pumping light sources for frequency up-conversion after being used for outputting light beams, and up-conversion of middle infrared thousands of nanometers can be realized.
The purpose of the wavelength division multiplexer 10 is to combine pump light of different wavelengths together for coaxial output.
The purpose of the achromatic focusing lens 11 is to beam-convert the pump light and focus it into a multi-period cascade waveguide 13.
The purpose of the dichroic mirror 12 is to combine the pump light with mid-infrared light, which has a high transmission for mid-infrared light and a high reflectivity for polychromatic pump light.
The multicycle cascade waveguide 13 adopts a multicycle cascade lithium niobate waveguide as a frequency up-conversion nonlinear medium, and the polarization period of the multicycle cascade waveguide is cascade arrangement of 34.8 mu m, 28.1 mu m, 25.8 mu m and 24.1 mu m, so that the broadband mid-infrared light can be converted into near infrared wave band. The optical channel of the waveguide can provide a strong confinement field for long distances, and the narrow structure can improve the average power of the polychromatic pump optical field, thereby improving the broadband frequency up-conversion efficiency.
The temperature control oven 14 is used to control the temperature of the crystal, stabilize the refractive index of the laser in the crystal, and thereby improve the stability of the optical resonant cavity of the system.
The purpose of the a-lens 15 is to collimate the light exiting the waveguide.
The filter 16 is a near infrared band-pass filter combination, and the transmission band range is 800nm-1100nm. The filter is used for idler photon filtering, filtering multicolor pump light, up-conversion fluorescence of the pump light, ambient stray light and the like.
The purpose of the b lens 17 is to collect the up-converted light so that it focuses the incident grating.
The purpose of the near infrared grating 18 is to spatially separate the up-converted spectrum, wherein the line 1200 lines/mm is used at wavelengths ranging from 400 to 1600nm.
The purpose of the metal mirror 19 is to change the direction of propagation of the optical path, with an average reflectivity of more than 99% over the 800nm-1100nm range.
The purpose of the c-lens 20 is to collect the light spatially separated by the dispersive system and focus the up-converted spectrum onto the detection array.
The CMOS array 21 is aimed at realizing ultrasensitive detection on the near infrared spectrum generated by up-conversion, and the detection wavelength range thereof covers 600-1700 nm, the resolution reaches 0.02nm, and the rapid measurement is 0.2s.
The purpose of the computer 22 is to process the up-converted spectrum acquired by the near infrared spectrometer and convert it into mid-infrared spectral information.
Referring to fig. 5, a specific implementation process of mid-red up-conversion spectrum detection of a multi-wavelength pump is as follows:
1) Multi-period cascaded waveguides are designed as a medium for nonlinear frequency conversion. Specifically, the design inversion cycle comprises a multi-cycle cascade waveguide 13 of 34.8 μm, 28.1 μm, 25.8 μm, 24.1 μm, placed on a temperature controlled oven 14.
2) The infrared signal 1 in broadband is collected into the multi-period cascade waveguide 13 through the germanium window sheet 2, the off-axis parabolic mirror 3, the sample 4 to be tested, the calcium fluoride lens 5 and the dichroic mirror 12, and is converted into the near infrared band through the broadband frequency up-conversion process. Specifically, broadband blackbody radiation emitted by a thermal light source is used as a mid-infrared continuous light source, visible light is filtered after passing through the germanium window sheet 2, the visible light is collected by the off-axis parabolic mirror 3, and infrared absorption spectrum information of a sample is carried after the infrared absorption spectrum information is absorbed by the sample 4 to be detected. The mid-infrared signal is then focused by the calcium fluoride lens 5 and spatially combined with the high power polychromatic pump light source by the dichroic mirror 12 into the optical channel of the multicycle cascade waveguide 13.
3) The high-power continuous pump light emitted by the a, b, c, d single-frequency continuous pump lasers 6, 7, 8 and 9 enters the multi-period cascade waveguide 13 through the wavelength division multiplexer 10, the achromatic focusing lens 11 and the dichroic mirror 12 to participate in the broadband mid-infrared frequency up-conversion process. Specifically, the multi-wavelength pump light is combined through the wavelength division multiplexer 10, coaxially output, focused by the achromatic lens 11, and is incident into the multi-period cascade waveguide 13 through the dichroic mirror 12 and the broadband mid-infrared space combined beam, and a stable high-power mixed pump light field is formed in the guide structure of the waveguide.
4) The mid-infrared signal light is converted into a near-infrared band through a broadband frequency up-conversion method and detected by a near-infrared detection array with excellent performance, so that mid-infrared high-performance detection with spectrum fine resolution capability in the range of thousands of nanometers is realized. Specifically, the signal spectrum transmission obtained by frequency up-conversion in the multi-period cascade waveguide 13 is collimated by the a lens 15, and the filter 16 filters out multicolor pump light, pump light up-conversion fluorescence and ambient stray light. Then, the b lens 17 spatially focuses the light, the near infrared grating 18 spatially separates the light, the light is refracted by the metal mirror 19, and the c lens 20 collects the light. Finally, the near infrared CMOS array 21 detects the sample, and the sample is converted into a spectrum absorption curve of the sample in a mid-infrared band through image processing of the computer 22, so that the up-conversion spectrum resolution of the mid-infrared ultrasensitive in the broadband is finally realized, and the resolution, the sensitivity and the spectrum forming speed are improved by orders of magnitude compared with those of the traditional mid-infrared spectrometer.
What has not been described in detail in the above embodiments belongs to the prior art known to the person skilled in the art. The above embodiments are only for illustrating the technical aspects of the present invention, not for limiting the same, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (4)
1. The method is characterized in that a multi-wavelength single-frequency narrow-band laser is adopted as pumping light, a multi-period nonlinear frequency up-conversion medium is used for realizing broadband mid-infrared coverage and high-efficiency mid-infrared frequency up-conversion, and a high-performance near-infrared dispersion and detection element is utilized for realizing mid-infrared spectrum detection with broadband, high resolution and ultrasensitivity, and the method specifically comprises the following steps:
step 1: irradiating a sample to be detected by a broadband mid-infrared light source to obtain broadband mid-infrared light of sample absorption spectrum information;
step 2: forming a multicolor pumping field by using the multi-wavelength pumping light beam, and spatially combining the multi-wavelength pumping light beam and the middle infrared signal light beam by using a dichroic mirror;
step 3: performing broadband frequency up-conversion under the action of a multi-wavelength pumping field through a multi-period nonlinear medium, and converting infrared signals into visible/near infrared bands;
step 4: and (3) utilizing a visible/near infrared dispersion element to split light, and utilizing a visible/near infrared detection array to obtain a spectrum, dividing the spectrum intensity of the sample and the spectrum intensity of the sample without the sample, and splicing the up-conversion spectrum to obtain an absorption spectrum line of the sample to be detected for the middle infrared.
2. The method for detecting mid-infrared up-conversion spectrum of multi-wavelength pump according to claim 1, wherein the wavelengths of the polychromatic pump fields are selected to ensure that up-conversion spectra under each pump condition do not overlap.
3. The method for detecting the mid-infrared up-conversion spectrum of the multi-wavelength pump according to claim 1, wherein the multi-wavelength pump light adopts single-frequency narrow-band laser, so that the wavelength after nonlinear conversion corresponds to the wavelength of the mid-infrared signal one by one, and the spectrum information of the mid-infrared signal is kept.
4. The method for detecting mid-infrared up-conversion spectrum of multi-wavelength pump according to claim 1, wherein the multi-period nonlinear medium refers to quasi-phase period extremum corresponding to nonlinear conversion under different pump wavelength conditions, and a crystal or waveguide structure with discrete period change is designed to obtain a broadband phase matching window to cover the mid-infrared spectrum range to be detected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310164295.5A CN116183536A (en) | 2023-02-24 | 2023-02-24 | Mid-infrared up-conversion spectrum detection method of multi-wavelength pump |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310164295.5A CN116183536A (en) | 2023-02-24 | 2023-02-24 | Mid-infrared up-conversion spectrum detection method of multi-wavelength pump |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116183536A true CN116183536A (en) | 2023-05-30 |
Family
ID=86440113
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310164295.5A Pending CN116183536A (en) | 2023-02-24 | 2023-02-24 | Mid-infrared up-conversion spectrum detection method of multi-wavelength pump |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116183536A (en) |
-
2023
- 2023-02-24 CN CN202310164295.5A patent/CN116183536A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4791363B2 (en) | A system using parametric broadband light for real-time remote chemical detection | |
| US10571335B2 (en) | Methods and apparatus for spectral imaging | |
| Kanda et al. | Real-time broadband terahertz spectroscopic imaging by using a high-sensitivity terahertz camera | |
| WO2021117632A1 (en) | Quantum absorption spectroscopy system and quantum absorption spectroscopy method | |
| CN109100310B (en) | Ultra-spectrum detection micro-system | |
| EP3019912B1 (en) | Multi-channel up-conversion infrared spectrometer and method of detecting a spectral distribution of light | |
| WO2018007572A1 (en) | Infrared upconversion spectrometer for the mid-ir range | |
| Signorini et al. | A silicon source of heralded single photons at 2 μm | |
| US20230099476A1 (en) | Mid-infrared upconversion imaging method and device | |
| Liu et al. | Mid-infrared cross-comb spectroscopy | |
| US10969276B2 (en) | Dual-frequency-comb spectrometer and spectroscopy method for spectroscopic investigation of a sample | |
| US11226534B2 (en) | Methods and apparatus for generating mid-infrared frequency combs | |
| Gambetta et al. | Scanning micro-resonator direct-comb absolute spectroscopy | |
| Phal et al. | Design considerations for discrete frequency infrared microscopy systems | |
| CN118111561A (en) | Mid-infrared single-photon time domain stretching spectrum method and device | |
| Ge et al. | Thermal camera based on frequency upconversion and its noise-equivalent temperature difference characterization | |
| CN112595416A (en) | Broadband infrared spectrometer | |
| US11965827B2 (en) | Hyperspectral imaging method and apparatus | |
| Molina et al. | Enhanced Infrared Vision by Nonlinear Up‐Conversion in Nonlocal Metasurfaces | |
| CN116183536A (en) | Mid-infrared up-conversion spectrum detection method of multi-wavelength pump | |
| CN115389441A (en) | High-precision mid-infrared spectrum detection method | |
| CN117213804B (en) | Medium infrared micro-ring resonator performance testing device based on frequency up-conversion | |
| Liu et al. | Broadband, High Resolution, Sensitive Spectrometer Using an Integrated Optical Phased Array in Silicon Nitride and Fourier Imaging | |
| CN115308155A (en) | Medium-wave infrared high-speed hyperspectral imaging method | |
| Jiang et al. | Fast frequency upconversion imaging based on quasi-phase match |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |