112 results about "Birefringent crystal" patented technology

The invention discloses a method for detecting residual stress of a birefringent crystal, which is characterized by comprising the following steps of: fixing a sample to be detected on a sample loading table; the imaging lens is used for acquiring light rays which sequentially penetrate through the polarizer module, a sample to be detected on the sample loading table, the analyzer module and the camera module in four states in three states that polarization axes of the polarizer module and the analyzer module are mutually orthogonal and a polarization angle is gradually increased by 30 degrees, and in a state that the polarizer module and the analyzer module are in parallel, and the imaging lens is used for acquiring the light rays which sequentially penetrate through the polarizer module, the sample to be detected on the sample loading table, the analyzer module and the camera module in the four states; collecting a light intensity matrix set through a camera module; acquiring a reference light intensity matrix through normalized linear superposition, and performing pixel-by-pixel operation with the reference light intensity matrix on the basis of the first light intensity matrix, the second light intensity matrix and the third light intensity matrix to acquire corresponding phase delay matrixes; eliminating natural birefringence and updating a phase delay matrix by deducting respective overall average phase delay amount pixel by pixel; through pixel-by-pixel weighted stacking, isogradient lines are eliminated, and distribution information of residual stress is obtained.

The invention discloses a spectral imaging calculation system based on spectral response enhancement of a color detector, and belongs to the technical field of spectral imaging, the spectral imaging calculation system comprises a birefringence light splitting module and a color detector, the birefringence light splitting module comprises a polarizer, a birefringence crystal and a polarization analyzer, the polarizer, the birefringent crystal, the polarization analyzer and the color detector are sequentially and coaxially arranged along an optical axis; the color detector is also electrically connected with a signal processing module; incident light is converted into linearly polarized light through the polarizer, the linearly polarized light is decomposed into o light and e light through the birefringent crystal, and the o light and the e light are combined into emergent light through the polarization analyzer. The emergent light passes through a color detector to obtain a measurement signal; and the signal processing module receives the measurement signal and reconstructs a spectral image in combination with the spectral response matrix of the birefringence light splitting module and the spectral response function of the color detector. The spectral response characteristics of multiple color channels of the color image sensor are combined with the birefringence color development polarization principle, the rank of a spectral response matrix is expanded, and the spectral resolution and the imaging precision are improved, so that the spectral information of a substance is more accurately acquired and analyzed.

The invention relates to a sulfur-antimony-lanthanum-barium compound, a sulfur-antimony-lanthanum-barium mid-far infrared birefringent optical crystal and a preparation method and application thereof, relates to a mid-far infrared birefringent crystal and a preparation method and application thereof, and aims to solve the problem of low birefringence of the existing mid-far infrared crystal, the sulfur-antimony-lanthanum-barium compound has the chemical formula of Ba2La2Sb4S10 (S2) and the molecular weight of 1424.22, is crystallized in a monoclinic system, and has the molecular weight of 294nm. The space group is P21 / c, and the cell parameters are as follows: a = 8.6373 (5), b = 14.7336 (9), c = 15.9161 (9), alpha = gamma = 90 degrees, and beta = 92.661 (2) degrees. Preparing a compound or a polycrystal material by using a high-temperature solution or a solid-phase method; a polycrystalline material is used for growing a single crystal, the birefringence of the single crystal is 0.53 at the position of 1064 nm, the single crystal has large birefringence within the range of 1-14 microns, and the single crystal is used in an optical isolator, a circulator, a beam shifter, an optical polarizer or an optical modulator.

The present invention relates to the technical field of artificial crystal materials, and more specifically to a birefringent crystal material, its preparation method, and its application. The present invention provides a new birefringent crystal material having the chemical formula [C(NH2)3][ICl4] and exhibiting a large birefringence. The preparation method for this birefringent crystal material utilizes raw materials with low human toxicity, a short crystal growth cycle, low cost, and high crystal purity. This birefringent crystal material can be used as a polarization optical device in the fields of optics and communications.

The utility model relates to the technical field of laser equipment, in particular to a laser assembly, a solid-state laser and laser processing equipment, and the laser assembly comprises a birefringent crystal which is used for emitting solid-state laser under the pumping effect, and the solid-state laser comprises two pieces of orthogonal polarized light with different wavelengths; the Q switch is arranged at one end of the birefringent crystal and is used for controlling the output of the solid-state laser; and the dual-wavelength output coupler is arranged at one end, deviating from the birefringent crystal, of the Q switch and is used for coupling and outputting two orthogonal polarized lights in the solid-state laser. Through the mode, the energy loss in the laser pumping cavity can be reduced, so that the laser threshold value is reduced, and the laser output power is improved.

A high extinction-ratio rotator includes a collimator that can collimate a signal light from an optical fiber, a pair of polarizing splitting prisms that include a first birefringence crystal wedge and a second birefringent crystal wedge, that can separate two orthogonal polarization components of the signal light into a vertically polarized light and a horizontally polarized light, a non-reciprocal 45-degree polarization rotator which the vertically polarized light and the horizontally polarized light exiting the pair of polarizing splitting prisms pass through, and a reflector. The vertically polarized light and the horizontally polarized light exiting the non-reciprocal 45-degree polarization rotator intersect on a surface of the reflector and are reflected back into the non-reciprocal 45-degree polarization rotator.

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.

This invention relates to a nonlinear optical crystal of potassium triacetate dihydrate, its preparation method, and its uses. The molecular formula of the crystal is K3C6O8H. 10 It has a molecular weight of 331.62, belongs to the orthorhombic crystal system, and has a space group of [missing information]. P 212121, cell parameters are a =8.7596(5)Å, b =10.0487(6)Å, c =13.9979(6)Å, α =90.00° β =90.00° gamma =90.00° Z =4, V =1232.13(11)Å 3 Centimeter-sized crystals were grown using an evaporation method and an aqueous solution cooling method. Under 1064nm laser irradiation, the powder frequency doubling effect of this crystal was equivalent to that of KH₂PO₄. 4 (KDP). This crystal has an ultraviolet absorption edge shorter than 200 nm and an experimental birefringence of approximately 0.06 at 546 nm. It is simple to prepare, low in cost, exhibits significant nonlinear optical effects, a large birefringence, a wide transmission range, and is easy to grow and process. It can be used as an ultraviolet nonlinear optical crystal and a birefringent crystal.

The present invention discloses a three-port reflective optical circulator based on a birefringent crystal, belonging to the field of optical communications. The three-port reflective optical circulator comprises a first birefringent crystal, a half-wave plate assembly, a roof prism, a Faraday rotator crystal, a second birefringent crystal, a quarter-wave plate, and a reflector, which are arranged in sequence. The first port, the second port, and the third port are respectively located on a side of the first birefringent crystal away from the half-wave plate assembly. The birefringent crystal performs light splitting to split a light beam into two sub-beams, o-polarized light and e-polarized light, with mutually perpendicular polarization directions. The polarization directions of the sub-beams are controlled by the half-wave plate, the quarter-wave plate, and the Faraday rotator crystal. Finally, the birefringent crystal performs light combining, thus realizing the functions of the optical circulator with input at the first port and output at the second port, and with input at the second port and output at the third port. The three ports are located on the same side of the optical circulator, making it easier to arrange other components and miniaturizing the optical circulator.

The present invention provides a two-dimensional array multi-channel, multi-port optical circulator, comprising two or more collimator arrays, each collimator array comprising three or more collimators, with the collimators in the same collimator array being located on the same side of the optical circulator; a first birefringent crystal disposed on one side of the collimator array, through which optical signals from the multiple collimator arrays all pass; a half-wave plate assembly disposed on a side of the first birefringent crystal away from the collimator array, the half-wave plate assembly comprising two or more half-wave plates; an optical rotator disposed on a side of the half-wave plate assembly away from the first birefringent crystal, a light combining and splitting device disposed on the side of the optical rotator assembly away from the half-wave plate assembly; a polarization state converter disposed on a side of the optical rotator assembly away from the light combining and splitting devices; and a reflector disposed on a side of the polarization state converter away from the optical rotator assembly. The present invention can integrate a multi-channel, multi-port optical circulator, facilitating miniaturization of the optical circulator.

The invention relates to a guanidino hydantoin methanesulfonate nonlinear optical crystal as well as a preparation method and application thereof. The molecular formula of the crystal is C3N3OH < 6 > (CH3SO3), the molecular weight is 195.2, the crystal belongs to an orthorhombic system, the space group is P212121, and the cell parameters are as follows: a = 5.5142 (5), b = 8.6892 (7), c = 17.4413 (16), alpha = 90.00 degrees, beta = 90.00 degrees, gamma = 90.00 degrees, Z = 4 and V = 820.5 (3) 3. Under the irradiation of 1064nm laser, the powder frequency-doubled effect of the crystal is about 3-5 times that of KH2PO4 (KDP), the ultraviolet absorption edge of the crystal is about 217nm, and the experimental birefringence is about 0.08-546nm. And growing crystals with the size of more than centimeter by adopting an evaporation method, an aqueous solution cooling method or a solvothermal method. The crystal is simple in preparation method and low in cost, has a relatively large nonlinear optical effect, a relatively large birefringence and a wide transmission range, is easy to grow and process, and can be used as an ultraviolet nonlinear optical crystal and a birefringence crystal.

Method for laser material processing using a processing laser beam (3), wherein a first laser beam (8a), which is coupled into at least a first fiber core (9a) of an optical multicore fiber (9), and a second laser beam (8b), which is coupled into at least a second fiber core (9b) of the multicore fiber (9), are generated from a polarized input laser beam (5) using a birefringent crystal (7), wherein by influencing the polarization of the input laser beam (5) the ratio in which the power of the input laser beam (5) is divided between the first and the second laser beam (8a, 8b) is changed with a modulation frequency (f) between 1 Hz and 100 kHz, in particular between 100 Hz and 100 kHz, and thereby the first and the second laser beam (8a, 8b) can be coupled out of the multi-core fiber (9) alone or together as a processing laser beam (3). characterized by that the polarization is influenced by switching between linearly, circularly or elliptically polarized polarization by means of an electro-optic polarization modulator (6), in particular a Pockels cell or Faraday rotator, which can be controlled with the modulation frequency (f) to change the polarization of the input laser beam (5).

The application discloses a single-mode fiber to multi-mode fiber mode converter which comprises a single-mode fiber head assembly, a transmitting end C lens, a birefringent crystal sequence, a receiving end C lens and a multi-mode fiber head assembly arranged coaxially; an air gap is arranged between the light emitting end of the single-mode fiber head assembly and the transmitting end C lens, and an outer envelope tube of the transmitting end collimator is coaxially fixed to the outer circumferential side of the single-mode fiber head assembly and the transmitting end C lens; the single-mode fiber to multi-mode fiber mode converter can stably assemble each optical component and ensure the overall assembly precision by means of the outer envelope tubes of the transmitting end and receiving end collimators and the inner and outer envelope tubes of the crystal group; all the components are packaged by the overall outer envelope tube, the internal optical structure is effectively protected, and the firmness of the device structure is enhanced.

The invention belongs to the technical field of optical detection, and particularly relates to the field of optical wavefront detection, in particular to a lateral shear interference wavefront detection system and method based on an orthogonal polarization birefringent crystal. The system comprises a laser light source, wherein a polarizer and a beam splitter prism are sequentially arranged on an emergent light path of the laser light source; the invention discloses a polarization birefringent crystal, a reflector and a polarization camera. The method comprises the following steps: processing four phase shift interferograms, and extracting a wavefront gradient by using an arc tangent function; solving the system of linear equations to determine wavefront phase distribution by adopting an integral algorithm based on a least square method; and based on the extracted wavefront gradient, performing quantitative phase imaging by using a phase recovery algorithm. The device is simple in structure, high in stability and high in light energy utilization rate; the method is good in real-time performance, high in precision, capable of effectively restraining noise influences, capable of improving the precision of wavefront measurement, capable of meeting the requirement for high-precision optical system detection and wide in application range.

An integrated electro-optical non-reciprocal mode converter based on birefringent crystal refractive index matching comprises a chip, the upper layer of the chip is an electro-optical material film with birefringent characteristics, a mode converter is prepared on the electro-optical material film, and the mode converter is a two-port device; the first port is used for receiving an input optical signal of a mode 1 and allowing the optical signal to enter the mode converter; and the second port is used for outputting the converted optical signal in the mode 2. The refractive index difference of a birefringent material to a transverse electric mode (TE) and a transverse magnetic mode (TM) is utilized to realize the pre-coarse matching of the refractive indexes of TE and TM modes, and then the fine matching of the refractive indexes and wave vectors is realized in combination with electro-optical modulation, so that the integrated electro-optical mode converter insensitive to the process is realized. The device is simple in structure and has a wide application prospect.

The present invention discloses a high extinction ratio optical rotator, which sequentially includes a collimator, a polarization beam splitting prism pair, a non-reciprocal 45-degree polarization rotator, and a mirror along the optical path direction; the polarization beam splitting prism pair is composed of a first birefringent crystal wedge plate and a second birefringent crystal wedge plate with mutually perpendicular optical axis directions. The optical axis of the first birefringent crystal wedge plate is parallel to the vertical plane, and the optical axis of the second birefringent crystal wedge plate is perpendicular to the vertical plane; the polarization beam splitting prism pair separates two orthogonal polarization components of the input signal light. After passing through the polarization beam splitting prism pair, the signal light is divided into vertically polarized light and horizontally polarized light with orthogonal polarization states, and the intersection point of the vertically polarized light and the horizontally polarized light is located on the surface of the mirror. By setting the polarization beam splitting prism pair, the present invention eliminates the deviation of the polarization rotation angle of the polarization rotator caused by factors such as temperature, wavelength, and processing tolerance, ensuring that the signal light passing through the optical rotator can obtain a high extinction ratio.

This invention relates to a novel birefringent crystal, its preparation and application, and belongs to the field of optical technology. The chemical formula of the birefringent crystal is Na₂ZnB₆O. 11 Na₂ZnB₆O₆ belongs to the monoclinic crystal system, space group C2 / c. This crystal can be prepared in an open system using high-temperature solid-state and high-temperature solution methods. It exhibits excellent birefringence, with a birefringence of 0.094 at 1064 nm and a transmittance of 53% at the ultraviolet cutoff edge of 190 nm. The Na₂ZnB₆O₆ prepared by the method described in this invention... 11 Birefringent crystals can be used to make polarization elements such as optical isolators, circulators, Glan prisms, and optical polarizers, and have important applications in the fields of optics and information communication.

The present invention provides a Ba3Sc2(BO3)4 ultraviolet birefringent crystal, preparation and application. The Ba3Sc2(BO3)4 ultraviolet birefringent crystal has a centrosymmetric structure, belongs to the trigonal crystal system, has a space group of P-3m1, and has unit cell parameters of #imgabs0##imgabs1#α=90°, β=90°, γ=120°, Z=1, #imgabs2#. The room temperature transmission spectrum shows that the ultraviolet birefringent crystal has a wide transmission range (0.2~3.5μm), a transmittance of more than 70%, a short ultraviolet cutoff edge (198nm) and a large birefringence (Δn=0.145), and has the advantages of stable physicochemical properties, good mechanical properties, not easy to deliquesce, easy to cut, polished and stored, and is expected to be widely used in the field of ultraviolet birefringent optical materials. In the present invention, a flux method is adopted to prepare the ultraviolet birefringent crystal, which is simple to operate, the raw materials are readily available, and the preparation conditions are easy to achieve.

The invention provides a reflective optical circulator and a manufacturing method thereof, and the optical circulator comprises a collimator array, one end of the collimator array is provided with a first birefringent crystal, one end, far away from the collimator array, of the first birefringent crystal is provided with a half-wave plate group, one end, far away from the first birefringent crystal, of the half-wave plate group is provided with a rotating device, and the other end, far away from the first birefringent crystal, of the rotating device is provided with a second birefringent crystal. A second birefringent crystal is arranged at one end, away from the half-wave plate group, of the rotating device; an achromatic wave plate group is arranged at one end, far away from the rotating device, of the second birefringent crystal, the first half-wave plate is arranged close to the second birefringent crystal, and the quarter-wave plate is arranged far away from the second birefringent crystal; with the bottom surface of the reflective optical circulator as a reference, the optical axis of the first half-wave plate is 75 degrees, and the optical axis of the quarter-wave plate is 15 degrees; and a reflecting device is arranged at one end, far away from the second birefringent crystal, of the achromatic wave plate group. The invention further provides a manufacturing method of the optical circulator. According to the invention, the return loss of the optical circulator can be effectively reduced.

The invention provides a reflective bidirectional light-passing magneto-optical switch, which relates to the technical field of optical communication and comprises an optical fiber collimation coupling unit, a polarization beam splitting and combining unit, a polarization state regulation and control unit, a reflection unit and a magnetic field generation and control unit which are sequentially arranged along an optical path. The 45-degree half-wave plate and the Faraday optical rotation crystal are configured to regulate and control light beam polarization, and it is ensured that optical signals are accurately guided to the output end after passing through the birefringent crystal. According to the design, the input port and the output port are integrated on the same side, compared with a transmission type structure, the magneto-optical switch has the advantages of being small in size, high in material utilization rate and compact in layout, the flexibility and adaptability of the magneto-optical switch are remarkably improved, bidirectional reversible transmission of an optical path is achieved, and the application requirement for bidirectional information interaction between channels is met.

The present application relates to the field of optical communication technology, and specifically relates to a kind of multi-channel shift circulator.It includes optical fiber unit, birefringent crystal, polarization unit, transmission or reflection unit, polarizer and reflecting element;Optical fiber unit includes at least four optical fibers, and optical signal can enter and reach birefringent crystal along any optical fiber, and birefringent crystal is used to split beam O light and E light;Transmission or reflection unit includes a plurality of PBS films, and the setting number of PBS film is same with optical fiber;Polarization unit changes the polarization state of O light and E light, so that O light and E light pass through corresponding PBS film;Enter polarizer and reflect back to polarizer by reflecting element, change the polarization state of O light and E light, so that O light and E light are reflected on corresponding PBS film to adjacent PBS film;Polarization unit can change the polarization state of reflected light, so that reflected light is combined after birefringent crystal and exits along corresponding optical fiber.Equipped with more than three ports to adapt to the application scene of the transmission of optical signal.

The utility model provides a four-channel integrated optical fiber isolator, which relates to the field of optical fiber communication and comprises a tube shell, a first optical fiber collimator and a second optical fiber collimator are respectively arranged at two ends of the tube shell, and four-core optical fibers are arranged in the first optical fiber collimator and the second optical fiber collimator. The four-core optical fibers in the first optical fiber collimator are in one-to-one correspondence with the four-core optical fibers in the second optical fiber collimator; an isolator core is arranged between the first optical fiber collimator and the second optical fiber collimator, the isolator core comprises an outer tube, a first birefringent crystal corresponding to the first optical fiber collimator and a second birefringent crystal corresponding to the second optical fiber collimator are arranged in the outer tube, and an optical rotation sheet is arranged between the first birefringent crystal and the second birefringent crystal. Compared with the prior art, the four-channel integrated optical fiber isolator has the advantages that the functions of four isolators are realized by using the boundary dimension of one conventional isolator, the use space is greatly reduced, only one isolator core and two four-core collimators are used, and the cost is saved.

The invention belongs to the technical field of birefringent crystal material preparation, and relates to a birefringent crystal and a preparation method and application thereof. The chemical formula of the birefringent crystal is (C6H7N2O) (NH2SO3), the birefringent crystal belongs to an orthorhombic crystal system, and the space group of the birefringent crystal is Pna21; the cell parameters are as follows: a is equal to 17.2986 (5); b is equal to 7.3895 (3); c is equal to 6.6272 (2); alpha = beta = gamma = 90 degrees. The birefringent crystal is in a colorless transparent sheet shape, and the ultraviolet cut-off edge is 274 nm; meanwhile, the crystal has large birefringence, and the birefringence value is 0.452 nm and 535 nm and far exceeds that of an existing commercial crystal. The preparation method comprises the following steps: taking nicotinamide and sulfamic acid as raw materials (molar ratio is 1: 1), carrying out normal-temperature liquid phase reaction, and cooling / evaporative crystallization, so that the nicotinamide derivative is prepared, the process is simple, the cost is low, and the repeatability is high.

The invention belongs to the technical field of birefringent crystal materials, and particularly relates to a birefringent crystal and a preparation method and application thereof. The chemical formula of the birefringent crystal is Na6 [ZnF2 (B12O24H6)], the birefringent crystal belongs to a trigonal system, the space group is R-3c, and the cell parameters are alpha = 90 degrees, beta = 90 degrees and gamma = 120 degrees. The crystal belongs to an indirect band gap compound, the band gap of the crystal is 4.10 eV, and the crystal has high thermal stability which can reach 380 DEG C. The birefringence of the crystal is delta n = 0.05 at 546 nm, and the crystal is a potential birefringence crystal material.

The present invention provides a compound, calcium guanidine nitrate, and a birefringent calcium guanidine nitrate crystal, as well as a preparation method and use thereof. The chemical formula of the compound is [C(NH2)3]2Ca(NO3)4(H2O)2, the molecular weight is 444.33, and the compound is prepared by a solvent thermal method. The crystal chemical formula is [C(NH2)3]2Ca(NO3)4(H2O)2, the molecular weight is 444.33, and the crystal belongs to the monoclinic system with a space group of C 2 / c , the unit cell parameters are a =20.319(3)Å, b =6.5717(8)Å, c =14.2195(16)Å, α =90°, β =116.399(5)°, c =90°, the unit cell volume is 1700.8(4)Å 3 , with a transmittance range of 281-1600 nm and a birefringence index between 0.152 (1064 nm) and 0.23 (281 nm). Grown using a room-temperature aqueous solution method, the resulting birefringent crystals possess moderate mechanical hardness, are easily cut, polished, and stored, and are easy to grow under simple growth conditions. They are insoluble in water, non-deliquescent, and stable in air. They exhibit a wide transmittance range and birefringence, and can be used to fabricate polarization beam splitters, phase delay devices, and electro-optical modulators.

The application provides a reflective optical circulator and a manufacturing method thereof. The optical circulator comprises a collimator array, one end of the collimator array is provided with a first birefringent crystal, the first birefringent crystal is provided with a half-wave plate group away from one end of the collimator array, the half-wave plate group is provided with a rotating device away from one end of the first birefringent crystal, and the rotating device is provided with a second birefringent crystal away from one end of the half-wave plate group; the second birefringent crystal is provided with an achromatic wave plate group away from one end of the rotating device, a first half-wave plate is arranged close to the second birefringent crystal, and a quarter-wave plate is arranged away from the second birefringent crystal; the optical axis of the first half-wave plate is 75 degrees and the optical axis of the quarter-wave plate is 15 degrees based on the bottom surface of the reflective optical circulator; and a reflecting device is arranged away from one end of the achromatic wave plate group. The application also provides a manufacturing method of the optical circulator. The application can effectively reduce the return loss of the optical circulator.

The present invention discloses a birefringent crystal and a preparation method thereof, belonging to the technical field of optical materials. The chemical formula of the birefringent crystal is (C 12 H8N2)SbF2(H2PO3); The space group of the birefringent crystal is the P-1 space group of the triclinic system; the unit cell parameters are α=106.324°, β=90.246°, γ=105.428°, and Z=2. The present invention adopts o-phenanthroline phosphite ionic liquid to synthesize birefringent crystals by an ionothermal method, which effectively solves the problem that Sb(III) is easily hydrolyzed. In the birefringent crystals prepared by the present invention, the N atoms on the o-phenanthroline ring chelate with the Sb atoms to form a coordination bond so that the lone pair of electrons of Sb always maintains a certain angle with the b-plane, which significantly improves the birefringence of the obtained birefringent crystals.

The application provides a full solid-state mode-locked laser double optical comb generating device, and relates to the technical field of optical frequency, and comprises a lens group (1), a dichroic mirror (2), a gain crystal (3), a first birefringent crystal (4), a second birefringent crystal (5) and a semiconductor saturable absorber mirror (6), wherein the pump source generates pump light which passes through the lens group (1) to converge a light spot, and passes through the dichroic mirror (2) and is connected with the gain crystal (3), the front and back sides of the gain crystal (3) are connected with the first birefringent crystal (4) and the second birefringent crystal (5) through optical connection respectively, and the second birefringent crystal (5) is connected with the semiconductor saturable absorber mirror (6); the pump light is divided into two polarized lights which are orthogonal to each other by the birefringent crystal, and the gain medium is directly pumped, so that the full solid-state mode-locked laser double optical comb with compact structure, large range of repetition frequency difference tuning and high mutual coherence is realized.

In some implementations, an optical isolator core includes a Faraday rotator and a plurality of birefringent crystal plates. The plurality of birefringent crystal plates may include a first birefringent crystal plate to separate input light into light having a first polarization and light having a second polarization, and a second birefringent crystal plate to combine the light having the first polarization and the light having the second polarization in output light that is laterally displaced by the single stage optical isolator. The Faraday rotator may be provided between the first birefringent crystal plate and the second birefringent crystal plate. In some implementations, the plurality of birefringent crystal plates further include a third birefringent crystal plate provided between the Faraday rotator and the second birefringent crystal plate. Additionally, or alternatively, the optical isolator core may further include a half-wave plate arranged between the Faraday rotator and the first birefringent crystal plate.

The invention relates to a fluorinated biuret borate nonlinear optical crystal and a preparation method and application thereof, the chemical formula of the crystal is [C2N3O2BF2H5] [BF4], the molecular weight is 238.71, and the crystal is prepared by a hydrothermal method or a room temperature solution method; the crystal belongs to a monoclinic system, the space group is P21, and the cell parameters are as follows: a = 6.0521 (11), b = 9.4651 (18), c = 7.1398 (12), beta = 91.267 (7), Z = 2, and V = 408.90 (13) 3. The [C2N3O2BF2H5] [BF4] nonlinear optical crystal obtained by the method is used for manufacturing a second harmonic generator, an upper frequency converter, a lower frequency converter, an optical parametric oscillator and the like; meanwhile, the crystal can also be used as a birefringent crystal for manufacturing a refractive index modulator, a phase modulator and a polarization device.