124 results about "Optical parametric oscillator" patented technology

The invention discloses a series of alkali metal borate compounds and alkali metal borate crystals as well as a preparation method and application thereof, and belongs to the technical field of photoelectric functional crystal materials. The chemical general formula of the series of compounds and crystals thereof is A3RE (B3O6) 2, wherein A is K, Rb, Cs or NH4; rE = Sc and Y, the molecular weight is 355.93-744.48, the series of crystals belong to a trigonal system, the space group is P321, the cell parameters a = b = 10.5237 (13)-135237 (13), and # imgabs0 # Z = 3. The series of alkali metal borate compounds are synthesized by adopting a solid-phase reaction method or a hydrothermal method, and the series of crystals grow by adopting a high-temperature melt method or a hydrothermal method or a solution method. The series of materials can be used for manufacturing second harmonic generators, upper and lower frequency converters, optical parametric oscillators, polarizing prisms and the like.

An optical parametric oscillator and method for generating coherent signal light involve a resonant optical cavity for coherent signal light, and in the cavity a non-parametric gain element for amplifying the coherent signal light to only partially compensate for passive optical roundtrip losses, thereby obtaining lower effective roundtrip losses. A parametric gain element is arranged in the cavity, for converting coherent pump light into coherent signal light through an instantaneous nonlinear optical interaction. The parametric oscillator has means for adjusting an intracavity optical power of the coherent pump light above a threshold value, where the parametric gain is balancing the effective roundtrip losses, thus inducing sustained oscillations of the signal light in the optical cavity. The non-parametric gain element is configured to have a limited non-parametric gain over a gain bandwidth of the parametric gain element, which is less than the passive optical roundtrip losses in the gain bandwidth.

The invention discloses an ultra-wideband femtosecond optical parametric oscillator capable of being quickly tuned, and relates to the technical field of optical parametric oscillators. The oscillator comprises a frequency doubling device, an optical parametric oscillator resonant cavity device and a dispersion compensation chirp mirror pair module. According to the invention, the original phase matching bandwidth is further broken through by adopting a non-collinear phase matching mode that the transmission included angle between the pump light and the signal light is 2.5 degrees, and rapid wavelength tuning can be realized only by finely tuning the cavity length under the condition that the angle of the nonlinear crystal is not adjusted; the broadband tunable optical parametric oscillator can break through the bottlenecks in the aspects of wavelength tuning range, wavelength tuning speed and the like of the existing near-infrared optical parametric oscillator, and provides a novel light source with larger wavelength tuning range and higher tuning speed for the fields needing broadband tunable light sources, such as spectroscopy, micro-nano processing, optical frequency combs and the like.

The invention provides a bright low-frequency compressed light generation device and method, and belongs to the technical field of non-classical light field generation. The problems that an existing bright compressed light generating device still has technical defects in the aspects of optical power, compression degree, stability, preparation device complexity and the like are solved. According to the technical scheme, laser generated by a single-frequency laser is divided into two beams after passing through a laser preparation module, one beam enters a frequency doubling cavity to generate frequency doubling light, fundamental frequency light reflected by the frequency doubling light is subjected to passive noise suppression, and fundamental frequency reflected light is subjected to further noise suppression in an active feedback control loop; the frequency doubling light serves as pump light to be injected into an optical parametric oscillator, a coherent control technology is used to generate a stable amplitude compression vacuum state light field, and the compression vacuum state light field and fundamental frequency reflection light after passive and active noise suppression are coupled on a 99: 1 beam splitter to generate bright low-frequency amplitude compression light; the method is applied to bright low-frequency compressed light generation.

A calculation device of the present disclosure is characterized by implementing an item, which expresses a magnetic field, at each site by adding, to the conventional coherent Ising machine, a function for simulating the magnetic field item. Specifically, light having the amplitude of a predetermined sign is input in the conventional coherent Ising machine by dislocating an operation point of the push-pull-type optical modulator. When the operation point is dislocated to a + direction, DOPO (Degenerate Optical Parametric Oscillator) having the same wavelength as that of DOPO of an optical resonator and having a fixed initial phase difference from pump light into which the light is injected considerably tends to oscillate at 0 phase, and becomes reversed when the operation point is dislocated to a minus direction.

A lidar system for simultaneously measuring the column concentration of methane and the profile concentration of water vapor in the atmosphere is disclosed. The device includes a laser emission module: a 1645nm monoline seed laser, a 1645nm offline1 seed laser, a 1645nm offline2 seed laser, a 1064nm pump laser, a laser frequency-locking module, an optical parametric oscillator, a frequency doubling module, and emitting optical components; an echo receiving module: an integrating sphere module, an optical receiving telescope assembly, a beam splitter, filter assembly 1, filter assembly 2, photodetector 1, and photodetector 2; and a data acquisition and processing module. This invention utilizes the frequency doubling relationship between the absorption lines of methane and water vapor to simplify the complex structure of a dual-band, multi-wavelength laser. It employs seed-injected optical parametric oscillator technology to obtain a high-frequency stable 1645nm fundamental frequency light, which is then frequency-doubled to obtain an 822nm laser. The profile concentration of water vapor and the column concentration of methane in the atmosphere can be measured using differential absorption lidar (DIAL) and integral path differential absorption (IPDA) technologies, respectively.

A stimulated Raman photothermal (SRP) microscope for imaging a sample. A first optical source without an optical resonator emits a pump beam. A second optical source emits an intensity-modulated Stokes beam. The Stokes beam is combined with the pump beam to form a combined beam. The combined beam is directed to the sample to induce a thermal effect caused by the stimulated Raman process. A third optical source emits a probe beam, the probe beam is directed to the sample. An optical detector detects modulation of the probe beam after modulation by the sample to measure an SRP signal. Because noise in the pump and Stokes beam do not significantly effect the measurements from the probe beam, these beams can use a high-powered optical parametric amplifier (OPA) source for improved sensitivity and imaging speed compared to SRP microscopes using an optical parametric oscillator (OPO) source.

The invention provides a preparation method and application of a compound cesium ammonium fluoborate and a cesium ammonium fluoborate nonlinear optical crystal. The chemical formula of the compound is CsNH4B8O12F2; the chemical formula of the crystal is CsNH4B8O12F2, the crystal belongs to a trigonal system, the space group is P321, and the unit cell parameters are as follows: a = b = 6.5858 (4) + / -0.02, c = 7.8163 (6) + / -0.02, alpha = beta = 90 degrees, gamma = 120 degrees and Z = 1. The crystal is grown by adopting a vacuum high-temperature solution method, a room-temperature solution method or a hydrothermal method, and the ultraviolet transmission cut-off edge of the crystal is lower than 190 nm. The nonlinear optical effect of the crystal is about 2.5 times of that of KH2PO4 (KDP), and the shortest I-type phase matching wavelength is 175.5 nm. The crystal has the advantages of simple preparation method, low toxicity of used initial raw materials, small harm to human bodies, stable physical and chemical properties, uniaxial crystal, easiness in application and the like. The method can be widely applied to nonlinear optical devices such as ultraviolet and deep ultraviolet all-solid-state lasers, optical parametric oscillators and the like.

The mid-infrared optical parametric oscillator pumped by the dual-wavelength nanosecond pulse solid laser can simultaneously output 1.9 micron laser and 2.1 micron laser, realizes broad spectrum / multi-wavelength output of the mid-infrared optical parametric oscillator, and can ensure that mid-infrared laser has excellent beam quality and relatively high output power. The output power of the 1.9 [mu] m optical fiber laser pumping source is hectowatt magnitude, and the 1.9 [mu] m optical fiber laser pumping source serves as a pumping source of a Ho crystal in the solid laser oscillator. In a Tm solid laser oscillator and a Ho solid laser oscillator, a resonant cavity comprises two plano-concave sub-cavities, the two plano-concave sub-cavities are a Tm crystal oscillation cavity and a Ho crystal oscillation cavity respectively, the two plano-concave sub-cavities share one output mirror, the Tm crystal oscillation cavity adopts a 793 nm semiconductor laser for pumping, and the Ho crystal oscillation cavity adopts a 1.9 [mu] m optical fiber laser pumping source I for pumping; in the phosphorus-germanium-zinc optical parametric oscillator, a planar four-mirror annular cavity is used as a single-resonance optical parametric oscillation cavity.

A stimulated Raman photothermal (SRP) microscope for imaging a sample. A first optical source without an optical resonator emits a pump beam. A second optical source emits an intensity-modulated Stokes beam. The Stokes beam is combined with the pump beam to form a combined beam. The combined beam is directed to the sample to induce a thermal effect caused by the stimulated Raman process. A third optical source emits a probe beam, the probe beam is directed to the sample. An optical detector detects modulation of the probe beam after modulation by the sample to measure an SRP signal. Because noise in the pump and Stokes beam do not significantly effect the measurements from the probe beam, these beams can use a high-powered optical parametric amplifier (OPA) source for improved sensitivity and imaging speed compared to SRP microscopes using an optical parametric oscillator (OPO) source.

This application discloses an optical parametric oscillator and a laser generating device, relating to the field of laser technology. The optical parametric oscillator includes a first optical fiber, a mirror assembly, a nonlinear crystal, and a second optical fiber. The first optical fiber has a first receiving end and a first output end. The first receiving end is used to receive pump light. The second optical fiber has a second receiving end and a second output end. Light output from the first output end can be transmitted to the second receiving end via the mirror assembly and the nonlinear crystal. The second output end is used to output signal light. The mirror assembly includes multiple mirrors. The nonlinear crystal is located in the optical path between two mirrors. A first grating is disposed on the first optical fiber, and a second grating is disposed on the second optical fiber. Both the first and second gratings are fiber Bragg gratings. Because this application uses a first optical fiber and a second optical fiber to define the light transmission path, compared to a free-space optical path, the optical fiber can be coiled, which is beneficial for reducing the overall size and improving integration.

This invention relates to a potassium hydroxyborate nonlinear optical crystal, its preparation method, and its applications. The crystal has the chemical formula K₂B₅O₈(OH), a molecular weight of 277.26, belongs to the orthorhombic crystal system, and has a space group of [missing information]. Pca 21, with unit cell parameters a=8.5523(8)Å, b=7.3326(7)Å, c=12.9739(10)Å, α=β=γ=90°, V=813.60(13)Å. 3 A nonlinear optical crystal composed of potassium hydroxyborate can be obtained using a mild hydrothermal (solvothermal) method through programmed or natural cooling. The frequency doubling effect of this crystal powder is approximately twice that of KDP (KH₂PO₄), and its ultraviolet cutoff edge is below 200 nm, making it suitable as a deep-ultraviolet nonlinear optical crystal. The crystal growth process offers advantages such as simple operation, low raw material toxicity, short growth cycle, low cost, and stable physicochemical properties. It has been widely applied in the fabrication of nonlinear optical devices such as frequency doubling generators, up- or down-frequency converters, or optical parametric oscillators.

The present disclosure belongs to the field of photoacoustic signal detection, and specifically relates to a quantum-enhanced all-optical photoacoustic signal detection device and method. The problem of low sensitivity of photoacoustic signals based on interference measurement is solved, and high-sensitivity detection of photoacoustic signals generated by living organisms including human bodies can be achieved. A degenerate optical parametric oscillator based on a first-type phase matching crystals is used for preparing a vacuum squeezed state light field, a coherent control technology is used for locking the squeezed angle to obtain the quadrature phase vacuum squeezed state, the prepared quadrature phase vacuum squeezed state light field is injected into the vacuum channel of a Michelson interferometer, and a balanced homodyne detection mode is used for achieving detection of the quantum-enhanced photoacoustic signals.

The present invention relates to a nonlinear optical converter (11) for a laser radiation source which comprises a pump laser for generating a pump laser beam, the nonlinear optical converter comprising: a first optical parametric oscillator (OPO) crystal (2) which faces the pump laser and which is designed to generate, from the pump laser beam (6), a first pair of gain bands, in particular a signal band and an idler band, as well as residual pump radiation, and which has a first phase-matching angle (7); and a second optical parametric oscillator (OPO) crystal (3) which is arranged downstream of the first optical parametric oscillator (OPO) crystal (2) and is designed to generate, from the residual pump radiation, a second pair of further gain bands, in particular a signal band and an idler band.

The invention provides an optical parametric oscillator. The optical parametric oscillator comprises a light beam emitting device and an optical parametric oscillation device. The optical parametric oscillation device comprises an oscillation cavity, a first nonlinear crystal and a second nonlinear crystal, wherein the first nonlinear crystal is arranged in the oscillation cavity and meets I-type phase matching, the second nonlinear crystal is arranged in the oscillation cavity and meets II-type phase matching, and the length ratio of the first nonlinear crystal to the second nonlinear crystal in the optical axis direction ranges from 1: 9 to 9: 1. When the optical parametric oscillation device works, fundamental frequency pump light emitted by the light beam emitting device enters the oscillation cavity, two beams of parametric light are generated under the action of the first nonlinear crystal and the second nonlinear crystal, the parametric light is resonated through the optical parametric oscillation device, and finally the required parametric light is output. Wherein the spectral line widths of the parametric light with the same wavelength generated by the first nonlinear crystal and the second nonlinear crystal are different, the first nonlinear crystal and the second nonlinear crystal are simultaneously placed in the oscillation cavity along the optical axis direction, and the output of the parametric light with different spectral line widths is realized by adjusting the length proportion of the two nonlinear crystals.

The present application belongs to but is not limited to the technical field of oscillator, and particularly relates to a cavity length locking system and method of a pulse type optical parametric oscillator, comprising an OPO pulse light source, a pulse width feedback locking loop and a power-based auxiliary locking loop; the OPO pulse light source comprises a seed pulse light source and an OPO resonant cavity; the pulse width feedback locking loop is composed of a pulse width measuring device, a signal processing circuit and a cavity length control element; the power-based auxiliary locking loop is composed of a power signal measuring device, a signal processing circuit and a cavity length control element. The locking system works simultaneously using the pulse width feedback locking loop and the power-based auxiliary locking loop. The pulse width feedback locking loop has a Hz level bandwidth and a high gain feature, and the power-based auxiliary locking loop has a kHz-MHz level larger bandwidth. The two are matched for application, and can realize more stable OPO cavity length locking.

This invention discloses a two-dimensional infrared spectroscopy system and its detection method that combines acid-base step and pulsed heating. The system includes a femtosecond laser, an optical parametric amplifier and difference frequency generator, a frequency divider, an electronic time delay generator, a nanosecond laser, a detachable optical parametric oscillator providing 355nm light pulses, an optical parametric oscillator providing 2020nm light pulses, a monochromator and a mercury cadmium telluride array detector, an integrator and data acquisition card, a computer, a chopper, a time-resolved pulse generation chamber, and a sample chamber. This invention retains the original pulsed heating trigger mode by using a nanosecond light source with a detachable optical parametric oscillator providing 355nm light pulses. It achieves convenient switching between the acid-base step and pulsed heating modes through a dichroic mirror and a reversible reflector. Before and after switching, the propagation direction of the nanosecond pulses is completely consistent, and the relative time delay is corrected by the electronic time delay device.

The application relates to a high-power mid-infrared optical parametric oscillation amplification device directly pumped by a Tm laser, and belongs to the technical field of high-power mid-infrared lasers. The device comprises a Tm:YLF seed laser, a Tm:YLF slab amplifier, a ZGP optical parametric oscillator and a ZGP optical parametric amplifier in sequence. The Tm:YLF seed laser outputs 1.908-micron fundamental light, the power of the 1.908-micron fundamental light is amplified through the Tm:YLF slab amplifier, and then the ZGP optical parametric oscillator and the ZGP optical parametric amplifier are directly pumped. The injection end and the output end of the Tm:YLF slab amplifier are both provided with a fundamental light coupling isolation system. A mid-infrared laser coupling isolation system is arranged between the ZGP optical parametric oscillator and the ZGP optical parametric amplifier. The ZGP optical parametric oscillator and the ZGP optical parametric amplifier are directly pumped by high-power Tm:YLF lasers, so that the power of the mid-infrared laser and the overall efficiency of the system are improved.

The purpose of the present invention is to provide an optical computer having high scalability and capable of reducing noise. This optical computer is characterized by including: an input layer which accepts an input signal as a computer; a reservoir layer which responds to a signal input from the input layer, and in which using a plurality of degenerate optical parametric oscillator (DOPO) pulses of a DOPO that are generated by an optical phase-sensitive amplifier (PSA) based on pump light as nodes, a connection relation between the nodes is determined by a measurement feedback method or a method equivalent to the measurement feedback method; and an output layer which outputs an output signal based on the respective responses of the plurality of DOPO pulses to the input signal from the reservoir layer.

The present application discloses a single-frequency continuous-wave optical parametric oscillator, comprising a pumping source, a focusing lens, a resonant cavity, an optical parametric down-conversion crystal, and a birefringent crystal. The resonant cavity comprises a concave-convex lens, an output planoconcave lens, and at least two transitional planoconcave lenses; and a waist spot of pump light obtained through the focusing lens is located between the concave-convex lens and a first transitional planoconcave lens adjacent to the concave-convex lens on a light path. The center of the optical parametric down-conversion crystal coincides with a waist spot of the pump light; the birefringent crystal is located at the beam waist between the output planoconcave lens and the second transitional planoconcave lens adjacent to the output planoconcave lens on the light path; and the birefringent crystal adopts a critical phase matching or non-critical phase matching mode.

A stimulated Raman photothermal (SRP) microscope for imaging a sample. A first optical source without an optical resonator emits a pump beam. A second optical source emits an intensity-modulated Stokes beam. The Stokes beam is combined with the pump beam to form a combined beam. The combined beam is directed to the sample to induce a thermal effect caused by the stimulated Raman process. A third optical source emits a probe beam, the probe beam is directed to the sample. An optical detector detects modulation of the probe beam after modulation by the sample to measure an SRP signal. Because noise in the pump and Stokes beam do not significantly effect the measurements from the probe beam, these beams can use a high-powered optical parametric amplifier (OPA) source for improved sensitivity and imaging speed compared to SRP microscopes using an optical parametric oscillator (OPO) source.

The invention belongs to the related technical field of picosecond laser regulation and control, and discloses a picosecond optical parametric oscillator for realizing near transformation limit output and a design method thereof, the oscillator comprises a pumping source laser, an optical resonant cavity, a nonlinear crystal and a dispersion element; the pumping source laser is used for providing pulse pumping light for the optical resonant cavity; the nonlinear crystal is arranged on a light path in the optical resonant cavity and is used for converting pump light into signal light and idler frequency light, the optical resonant cavity is used for realizing oscillation of the signal light, and the dispersion element is arranged on the light path in the optical resonant cavity and is used for introducing group velocity dispersion for the signal light; signal light and idler frequency light of the near conversion limit pulse are output from the optical resonant cavity, and the dispersion amount of the dispersion element meets the near conversion limit output requirement. The optical parametric oscillator provided by the invention not only can output near-conversion limit pulses, but also has the advantages of wide wavelength tuning range, high conversion efficiency, low cost and low loss.

The invention discloses an ultra-short pulse optical parametric oscillator based on a bicrystal structure, and relates to a laser and an assembly, and the oscillator comprises a first beam shaper (2) which is used for shaping idler frequency light (1); a second beam shaper (4) for shaping the pump light (3); a dichroscope (5); the first nonlinear crystal (6) is arranged on a light emitting path of the dichroscope (5), and the first nonlinear crystal (6) is used as an input coupling mirror of the optical parametric oscillator; the second nonlinear crystal (7) is arranged on a light emitting path of the first nonlinear crystal (6), and the first nonlinear crystal (6) and the second nonlinear crystal (7) form a resonant cavity; and the three-direction color mirror (9) is arranged on a light emitting path of the second nonlinear crystal (7) and is used for separating the pump light, the signal light (8) generated by nonlinear frequency conversion and the amplified idle frequency light (1) and transmitting and outputting the idle frequency light. The conversion efficiency of the optical parameter amplification process is improved, and the overall amplification performance of the optical parameter amplifier is guaranteed.

The application discloses a kind of high stability optical parametric oscillator assisted by intelligent feedback algorithm, and relates to the technical field of optical parametric oscillator.The oscillator includes 515 nm pump laser source, half-wave plate, polarization beam splitter, plane mirror, dichroic mirror, concave focusing cavity mirror, nonlinear crystal, output coupling mirror, four-quadrant photodetector based on STM32, DAC high-voltage drive board and piezoelectric deflection mirror.The application utilizes four-quadrant photodetector to monitor laser output power in real time, and collects data through the combination of ADC and direct memory access (DMA), realizes double buffering operation by means of full transmission and half transmission mechanism, to efficiently obtain the performance indicators required by SPGD algorithm.The algorithm continuously iterates and optimizes, controls piezoelectric deflection mirror in real time, precisely adjusts cavity length and beam pointing, and effectively stabilizes laser output power.

Wavelength-tunable source of pulsed laser radiation for VIS-NIR spectroscopy which consists of a pump source (1) forming bursts of picosecond pulses of high pulse repetition rate, and a synchronously pumped optical parametric oscillator (2). The pump source (1) comprises a solid-state regenerative amplifier (31) having one or two electro-optical switches (32,33) inside its resonator (44). The switches create partial transmission of the resonator for a time interval longer than a resonator roundtrip time, and eject a part of energy of a pulse circulating inside. Bursts of 5-10 ns duration are formed, which are filled with high peak power picosecond pulses. Pulse repetition rate of the order of GHz of pump pulses allows the construction of a compact optical parametric oscillator. The whole set of parameters ensures high energy efficiency, stability and an ability to provide output pulse bursts repeating at up to 10 kHz repetition rate.

The application discloses a rare earth magnesium gallium sulfur bifunctional material, a crystal thereof, a preparation method and application. The material has a chemical formula of LnMg6Ga6S 16 , wherein Ln is Nd or Sm, is crystallized in a hexagonal crystal system, and has a space group of P-6; the unit cell parameters of NdMg6Ga6S 16 are a=b=16.6585 Å, c=7.4046 Å; the unit cell parameters of SmMg6Ga6S 16 are a=b=16.653 Å, c=3.702 Å. The material has nonlinear optical performance and near-infrared luminescence performance. The polycrystalline powder of the material can be prepared by a vacuum high-temperature solid phase reaction method, and the crystal can be grown by a high-temperature melt method or a crucible lowering method. The obtained crystal can be used for preparing nonlinear optical devices such as a laser frequency doubling generator, a frequency converter, an optical parametric oscillator or an optical parametric amplifier, and can also be used for preparing near-infrared luminescence devices such as a near-infrared luminescence diode or a near-infrared laser.

The application discloses a device and method for generating 193nm waveband ultraviolet laser, which comprises a near-infrared laser driving unit 1, a nonlinear frequency conversion system 2 and an ultraviolet laser generating system 3 connected in sequence. The near-infrared laser driving unit is a high-power picosecond laser for generating near-infrared laser with a wavelength of 1064nm. The near-infrared laser is divided into two parts by a beam splitter, one part of which is used as pump light of a first optical parametric oscillator (OPO1) and generates 840nm laser, and the 840nm laser is converted into 210nm laser through four frequency doubling; the other part is directly used as pump light of a second optical parametric oscillator (OPO2) and generates 2380nm laser. In the last ultraviolet laser generating system, the 210nm laser and the 2380nm laser are combined through sum frequency mixing to finally realize the output of 193nm waveband ultraviolet laser. The application provides a new idea and technical route for the development of vacuum ultraviolet 193nm waveband solid-state laser by using mature nonlinear crystal and nonlinear frequency conversion process.

The application provides a narrow linewidth continuous tuning middle infrared optical parametric oscillator and a working method thereof. The middle infrared optical parametric oscillator comprises a pump source, a convex lens, a plane mirror, a MgO:PPLN crystal, a concave mirror, a first etalon, a second etalon and a plane output mirror which are arranged in sequence along an optical path in a resonant cavity. The MgO:PPLN crystal is placed in a temperature control furnace, the first etalon is provided with a heating sheet, and the thickness of the first etalon is greater than that of the second etalon. On the basis of crystal temperature tuning, the application combines a thermal tuning etalon to realize continuous wavelength tuning output.

A kind of lidar technology for atmospheric waveguide fast measurement, temperature and humidity profile, the key factor of atmospheric waveguide, can be measured simultaneously, the device includes laser emission module: 822nm online seed laser, 822nm offline seed laser, 1064nm pump laser, laser frequency locking module, optical parametric oscillator, acoustooptic modulator, frequency doubling module and emission optical assembly;Echo receiving module: optical receiving telescope and optical lens assembly, F-P filter, polarization light splitting prism, iodine molecular absorption cell, Fizeau interferometer and photodetector;Data acquisition and processing module.The present application fuses differential absorption lidar and two detection systems based on interferometer high spectral lidar, adopts seed injection optical parametric oscillator laser technology, obtains high frequency stability 822nm laser to realize atmospheric humidity profile fast measurement, remaining 532nm laser realizes atmospheric temperature profile fast measurement, finally inverts atmospheric waveguide parameter, realizes atmospheric waveguide efficient and accurate measurement.

This invention relates to a series of alkali metal rare earth chalcogenides and a series of alkali metal rare earth chalcogenide nonlinear optical crystals, their preparation methods, and their applications. The general chemical formula for both the series of halides and the nonlinear optical crystals is A3Ln. 11 Ga 19 Q 45 X3, where A = K, Rb, Cs; Ln = La, Pr, Nd; Q = S, Se; X = Cl, Br, I, all belong to the hexagonal crystal system with space group and cell parameter Z = 1. This series of halides is synthesized using a high-temperature solid-state method, while this series of nonlinear optical crystals is grown using a high-temperature solution method or the Bridgman process. This material can be used to manufacture second harmonic generators, up- and down-frequency converters, optical parametric oscillators, etc.