337 results about "Lithium niobate crystal" patented technology

The making process of lithium niobate modulator includes making substrate with lithium niobate crystal with proper crystal cutting direction and electric field utilizing direction; making light waveguide on the lithium niobate crystal; making modulating electrodes including central signal electrode and earth electrode and to form push-pull structure with the light waveguide; making microstrip matching structure in the input and output of the modulating electrodes; and setting buffering layer structure between the modulating electrode and light waveguide. Owing to the smart design of the modulating electrodes, the light waveguide and the matching structure in between, the lithium niobate modulator has high modulating rate, low insertion loss, high extinction ratio, low hemi-wave voltage, less electric reflection, and high reliability.

The invention relates to the non linear optical frequency conversion. To realize output of high power THz wave which can be continuously tuned, and stable running at room temperature, the technical scheme used by the invention is that: a tunable terahertz radiation source based on difference frequency cherenkov effect is composed of a laser device, a frequency doubling crystal, a double wavelength parametric oscillator, a harmonic mirror, a polarization filter, a combined beam mirror, a column lens and a difference frequency crystal; the harmonic mirror is placed between the frequency doubling crystal and the double wavelength parametric oscillator; the double wavelength parametric oscillator is II type phase matching KTP (Potassium Titanyl Phosphate) crystal OPO (Optical Parametric Oscillator); the polarization filter, the combined beam mirror and the column lens are arranged between the parametric oscillator and the difference frequency crystal; the difference frequency crystal is amagnesium oxide doped lithium niobate crystal with molecular formula of MgO:LiNbO3 or MgO:LN, and the generated THz wave is coupled and output by an Si prism on the side surface of the difference frequency crystal. The tunable terahertz radiation source based on difference frequency cherenkov effect is mainly applied to the optical frequency conversion.

A method and a system are implemented in the fabrication of a portable high power terahertz beam source that can produce a tunable, high power terahertz beam over the frequency from 0.1 THz to 2.5 THz. The terahertz source employs a recycling pump beam method and a beam quality control device. The beam quality control device may or may not be required for a high power terahertz beam generation. In exemplary embodiments, a lithium niobate (LiNbO3) crystal or a lithium niobate crystal doped with 5% magnesium oxide (LiNbO3:MgO) can be used. Other nonlinear optical crystals, including GaSe can be used in place of the LiNbO3 crystal. Through proper alignment of a pump beam, along with recycling a pump beam, high conversion efficiency is achieved, and a high output power beam is produced at terahertz frequencies.

In a method of producing a lithium niobate substrate by the use of a lithium niobate crystal grown by the Czochralski process, the lithium niobate crystal is heat-treated at a temperature of from 300° C. or more to less than 500° C. in the state the lithium niobate crystal is buried in a powder constituted of at least one element selected from the group consisting of Al, Ti, Si, Ca, Mg and C, or in the state the lithium niobate crystal is held in a container constituted of at least one element selected from the group consisting of Al, Ti, Si, Ca, Mg and C.

The invention discloses an optical waveguide, a method for preparing the same and a wavelength converter. The cross section of the optical waveguide is in a shape like a Chinese character 'tu'; a waveguide layer of a near-stoichiometric doped lithium niobate crystal with a poled chirp period is positioned on the upper layer of the optical waveguide, and is bonded with a lower substrate by a film of which the middle contains Si components. The embodiment of the invention improves the refractivity difference between the substrate and the waveguide layer, restrains the transmission of an opticalsignal in the optical waveguide and improves the conversion efficiency through film coating, widens pump bandwidth through the grating structure with the poled chirp period, reduces the photoinduced absorption effect under the irradiation of high-strong lasers and improves the conversion efficiency by adopting the waveguide layer of the near-stoichiometric doped lithium niobate crystal.

A optical parameter chirp pulse amplification laser system, includes a titanium gem femtosecond mode-locking pulse oscillator, a first splitting film, a CEP steady signal pulse source, an OPCPA synchronous pumping source, an OPCPA amplifier stage and compressor. In the output beam direction of the titanium gem femtosecond mode-locking pulse oscillator is the first splitting film, which divides a laser beam into a transmission light beam and a reflection light beam, and in the said transmission light beam is said CEP steady signal pulse source, OPCPA amplifier stage and compressor in order. The said CEP steady signal pulse source comprises a photonic crystal optical fiber, a chirp mirror, a period polarization lithium niobate crystal and a stretcher; said OPCPA amplifier stage comprises a first two-tone mirror, a first nonlinear crystal, a second two-tone mirror and a second nonlinear crystal; said OPCPA synchronous pumping source comprises a Q-tuning frequency-multiplier YAG laser, a narrowband titanium gem regenerating amplifier and a second splitting film, and a holophote. The invention apparatus may get a near-infrared ultrashort laser pulse output with a pulse width less than 30 femtoseconds.

The invention includes pumping source, optical couple lenses, input mirror and output mirror, nonlinear crystal C2 and its temperature controlling stove. Aperiodic poled Lithium Niobate crystal C1 is mounted between input mirror and output mirror and its temperature controlling stove with 100 Deg C.-200 Deg C. working temperature. When the pump beam lambdap = 1064 nm, the aperiodic poled crystal takes two signal beams lambda1=1500nm and lambda2=1510nm to make incidence to non linear crystal C2. 1450-1550nm reflection reducing coating film is coated on end face of non linear crystal. Poled period is 35um,a=23DEG. When working temperature of temperature controlling stove of Non linear crystal C2 is 100 Deg C.-200 Deg C., the frequency range produced by difference frequency of non linear crystal C2 is 1.19THz-1.45THz Terahertz wave.

The invention relates to a blackening method for a lithium tantalate or lithium niobate crystal substrate. The method comprises the following steps: preparing a mixed system from an elemental material with deoxidation ability and a mixture of a glue and a certain proportion of lithium carbonate powder; uniformly coating both sides of a to-be-treated lithium tantalate or lithium niobate crystal substrate by using a screen printing method; and placing the substrate in a stainless steel container, then putting the container into a heat treatment furnace, and carrying out reduction treatment on the to-be-treated lithium tantalate or lithium niobate crystal substrate in a nitrogen atmosphere with a flow of 6 L / min to 10 L / min under and at a temperature below the Curie temperature of the to-be-treated lithium tantalate or niobate crystal substrate. In the mixed system, organic silicone glue is used as glue; and the elemental material with deoxidation ability is Zn powder which accounts for 35% or less of the mass of the mixed system. According to the invention, reduced blackening treatment of the lithium tantalate or lithium niobate crystal substrate is carried out under Curie temperature conditions; and through blackening treatment, the pyroelectric properties of the substrate is reduced, and thus, manufacturing cost for a SAW filter is lowered and the production efficiency of the SAW filter is improved.

The invention discloses a high-efficiency super-smooth chemical mechanical polishing method for a lithium niobate crystal and belongs to the technical field of ultraprecision machining of nonlinear optical crystals. The high-efficiency super-smooth chemical mechanical polishing method is characterized in that a sample is a lithium niobate crystal; the lithium niobate crystal is processed by adopting a method of combining grinding of bonded abrasives, polishing of a retaining ring hard polishing pad and chemical mechanical polishing of a retaining ring soft polishing pad, wherein the hard polishing pad is a synthetic leather or polyurethane polishing pad; the soft polishing pad is non-woven fabric or fuzzy polishing pad; a pH value of a chemical mechanical polishing solution is 10.2-10.6; the chemical mechanical polishing solution contains four kinds of cerium oxide, silicon oxide, potassium hydroxide, sodium hydroxide, barium hydroxide, potassium permanganate, hydrogen peroxide, citric acid, acetic acid and oxalic acid; the grinding time of the bonded abrasives is 15-25 minutes; the polishing time of the hard polishing pad is 50-70 minutes; the chemical mechanical polishing time is 3-6 minutes; the removal rate of materials for chemical mechanical polishing is 420-460nm / min; the planeness of the polished lithium niobate is 3.8-5.5[mu]m; the surface roughness Ra of the polished lithium niobate is 0.35-0.5nm and the PV value of the polished lithium niobate is 3.8-6nm. The high-efficiency super-smooth chemical mechanical polishing method disclosed by the invention has the beneficial effect that a high-efficiency super-smooth polishing method of a nonlinear optical crystal is realized.

The invention discloses an iraser light source in the generation of an optical fiber type 3-5-micron continuous wave difference frequency and a method for achieving the same, wherein a pump light and a signal light adopt a wavelength sectional combining plan, a rare-earth-doped fiber laser with suitable wavelength is selected, a pump source adopts a ytterbium-doped fiber laser with a wave band of 1,060 nm and wave bands of over 1,100 nm, and the wave bands can be exchanged with each other. The signal light adopts an erbium-doped fiber laser with an S wave band, a C wave band and an L wave band, and the wave bands can be exchanged with each other. The ytterbium-doped fiber laser and the erbium-doped fiber laser emit the pump light and the signal light respectively, the pump light and the signal light are adjusted to be parallel with an optical axis of a crystal by a polarization controller respectively and are combined together by a fiber coupler, then a lens focusing system focuses the two light beams into a periodical polarization lithium niobate crystal; and by adjusting the length of the polarization cycle and the crystal temperature of the periodical polarization lithium niobate crystal, the pump light, the signal light and the difference frequency light meet a phase matching condition to finally achieve the infrared output in the generation of the difference frequency.

The invention provides a quasi-reciprocal optical closed-loop lithium niobate optical waveguide alternating electric field / voltage sensor. The quasi-reciprocal optical closed-loop lithium niobate optical waveguide alternating electric field / voltage sensor comprises a light source, a circulator, a polarizer, a phase modulator, a polarization-maintaining time delay optical fiber, a measuring optical path, a compensating optical path, a photodiode, a signal processing and light source driving circuit and a signal outputting and control interface. A polarization-maintaining optical fiber polarization shaft between the polarizer and the phase modulator is subjected to 45-degree counter-shaft fusion welding, a lithium niobate straight waveguide sensing unit of the measuring optical path and a compensating optical fiber of the compensating optical path are subjected to 90-degree counter-shaft coupling. Two cross-polarization modes participating in interference are interchanged when passing through the optical paths back and forth for two times and have the same optical path length, and a quasi-reciprocal reflection-type optical path for optical fiber conduction and waveguide sensing is formed. The quasi-reciprocal optical closed-loop lithium niobate optical waveguide alternating electric field / voltage sensor utilizes Pockels electrooptical effect of a lithium niobate crystal to modulate optical phases, achieves electric field / voltage measurement, has high sensitivity and measurement accuracy, can effectively separate components of direct current and alternating current of measured voltage and decrease a optical path space and is easily produced in a large-scale mode.

The invention provides a preparation apparatus and method of a lithium niobate crystal nano domain structure and is intended to solve the difficulty of the prior polarization technology in preparing a nano domain structure in lithium niobate crystal; the preparation apparatus and method are suitable for the preparation of nano domain structures in the field of ferroelectric crystal nano domain engineering, particularly for Z-tangential congruent lithium niobate crystal, magnesium-doped lithium niobate crystal and the like. The preparation method comprises the steps of first, constructing a domain wall structure in lithium niobate crystal; second, thermally treating a sample; third, secondarily polarizing the sample. By changing thermal treatment temperature and thermal treatment time, it is possible to prepare nano domain structures different in size; the size of the domain structures is generally of hundred nanometers level, and the depth thereof is of hundred micrometers level; by using the method, it is possible to prepare high-quality nano domain structures hundred micrometers in length; the method has the advantages that the method is simple to perform and is suitable for preparing nano domain structures in batch on a large scale.

The present invention relates to one kind of electrooptical angle measurer and belongs to the field of electrooptical detection technology. The present invention aims at real-time monitoring coaxial relative rotation angle of emitting platform and receiving platform separated by certain distance to realize second level angle measurement. The technological scheme of the present invention includes measurer comprising three parts of emitting part, receiving part and electric control part; grating outer-cavity semiconductor laser as light source; electrooptical lithium niobate crystal for loading angle information; polarizing light splitter and light detector for demodulating information; and differential processing technology used in processing obtained electrical signal. The present invention can complete angle measurement in second level precision with an angle measurer with compact structure, high vibration resistance and high long term stability.

The invention discloses a device and a method for preparing a waveguide and a grating by femtosecond laser etching. The device is formed by sequentially connecting a femtosecond laser, an optical polarizer, a beam splitter, a first reflector, a second reflector, a third reflector, a microobjective, lithium niobate crystals, a precision rotating platform, a three-dimensional electrical translation stage, an optical power meter and a computer. The device and the method solve the problem of how to control the laser condition and achieve an effect of using one femtosecond laser light source and only one set of processing equipment for simultaneously implementing preparation of the optical waveguide and the grating.

The 2D laser beam scanner consists of planar diffraction grating, collimating lens, horizontal scanning assembly on a socket, and vertical scanning assembly on a socket successively arranged in the light beam forward direction. The planar diffraction grating is in the focus plane of the collimating lens. The horizontal scanning assembly is one crystal plate array comprising several lithium niobate crystal plates in the same cutting structure and arranged in the optical axle direction, and the lithium niobate crystal plates have electrodes in sockets and in the equi-different lengths. The vertical scanning assembly has the same structure as the horizontal one but in vertical direction. The present invention has the features of fast scanning speed, high precision, no mechanism motion, simple structure, high stability and reliability and certain integration level.

In accordance with the present invention, a crystal laser material that is suitable for self doubling is presented. A crystal according to the present invention includes a stoichiometric lithium niobate crystal isomorph host material doped with at least one laser ion. In some embodiments, the stoichiometric lithium niobate crystal isomorph host material is lithium niobate. In some embodiments, the stoichiometric lithium niobate crystal isomorph host material is lithium tantalate. In some embodiments, the at least one laser ion includes Ytterbium. In some embodiments, the at least one laser ion includes a rare-earth ion. In some embodiments, the stoichiometric lithium niobate crystal isomorph host material is periodically poled to provide quasi-phase matching. Additionally, further dopant ions, for example Magnesium, can be included.

The invention discloses an electro-optical polarization rotator which comprises a silicon dioxide layer, a lithium niobate crystal film layer and an insulating medium protection layer sequentially arranged on a lithium niobate substrate, wherein a periodic lithium niobate ridge waveguide, a scribed groove and an embedded electrode arranged in the scribed groove are arranged in the lithium niobate crystal film layer; the polarized rotation of input light in the lithium niobate ridge waveguide is realized by applying an electric field in a lateral direction of the lithium niobate ridge waveguide through a transverse electro-optic effect. The electro-optical polarization rotator provided by the invention utilizes a periodically polarized lithium niobate ridge waveguide structure to have advantages of electro-optic control, small volume, low driving voltage, fast response, high polarization precision, integratability, high damage threshold and the like.

The invention provides a preparation method of a lithium niobate optical waveguide. The preparation method of the lithium niobate optical waveguide comprises the steps of: fabricating a periodical domain inversion structure on a doped lithium niobate crystal by adopting an applied electric field polarization method by selecting a zinc-doped or magnesium-doped lithium niobate crystal; bonding the periodical domain inversion structure as a waveguide layer with a lithium niobate substrate or a lithium tantalite substrate through optical cement the refractive index of which is lower than that of the waveguide layer; and etching to obtain a ridge waveguide structure by using an ICP (inductively coupled plasma) dry method to obtain the lithium niobate optical waveguide. The adhesive layer adopted by the invention has a reflective index more approaching that of air, therefore, in the waveguide, the optical field limiting function is stronger, the optical field is distributed symmetrically, and the coupling efficiency of single mode fibers is higher. By adopting adhesive bonding, the requirement on cleanness and roughness of the surface of a wafer is far lower than that of the surface of a directly bonded wafer, thus the preparation method is realized more easily in technology. The lithium niobate optical waveguide prepared by the method has more excellent performance in the aspects of improving the optical field limiting function, reducing the transmission loss of the waveguide, inhibiting the photorefractive effect, reducing the difficulty in manufacturing technology and the like.

The present invention provides a method for manufacturing a lithium niobate substrate by using lithium niobate crystals cultivated by the Zokoralski method, which is characterized in that the lithium niobate crystals are embedded in a substrate composed of Al, Ti, Si, In the state of powder consisting of at least one element selected from the group consisting of Ca, Mg, and C, or contained in at least one element selected from the group consisting of Al, Ti, Si, Ca, Mg, and C In the state in the container composed of elements, heat treatment is carried out at a temperature of 300°C or higher and less than 500°C.

In accordance with the present invention, a crystal laser material that is suitable for self doubling is presented. A crystal according to the present invention includes a stoichiometric lithium niobate crystal isomorph host material doped with at least one laser ion. In some embodiments, the stoichiometric lithium niobate crystal isomorph host material is lithium niobate. In some embodiments, the stoichiometric lithium niobate crystal isomorph host material is lithium tantalate. In some embodiments, the at least one laser ion includes Ytterbium. In some embodiments, the at least one laser ion includes a rare-earth ion. In some embodiments, the stoichiometric lithium niobate crystal isomorph host material is periodically poled to provide quasi-phase matching. Additionally, further dopant ions, for example Magnesium, can be included.

The invention provides a multiplier enhancing method based on periodically poled lithium niobate, and belongs to the technical field of optical information processing. The method includes firstly, performing room temperature electric field polarization on lithium niobate crystals, changing the polarization direction of the electric domain in a negative domain region of the +Z face of the crystals, and performing vacuum coating sputter electrode on two Y-directional sides of the crystals; then irradiated the crystals with a normal light and applying voltage of the two Y-directional sides of the lithium niobate crystals through a high voltage source simultaneously, and realizing ordinary light multiplier enhancement through produced slow light effects. According to the method, the quasi-phase matching technique (QPM) is creatively combined with effective light power enhancement resulted from the slow light effects.

The invention relates to a signal photon detector based on polarization unrelated frequency up-conversion; the signal photon detector comprises a lithium niobate crystal which is formed by periodically superposing four parts and is periodically polarized, wherein for a first part and a fourth part, the periodic structures are same, the period length is lA and meets the quasi-phase matching condition of frequency up-conversion, and the period number is NA so that all signal lights can be converted into sum frequency lights; a second part is in a periodic structure used by reciprocal lattice vectors for compensating mismatching of wave vectors coupled and polarized by signal lights, and the period length is lB and meets the phase matching condition of signal light polarization rotation; and a third part is in a periodic structure used by reciprocal lattice vectors for compensating mismatching of wave vectors coupled and polarized by sum frequency lights, the period length is lC and meets the phase matching condition of signal light polarization rotation. An external direct-current power supply is applied to y-surfaces of the second part and the third part of a sample so as to realize the periodic modulation of optical coefficients, thereby leading the polarization direction of corresponding light waves to rotate. The signal photon detector is practicable in preparation and has wide application prospect in fields of quantum communication and photo-communication.

The invention relates to a luminescent material and a preparation method thereof, particularly relates to a zirconium-ytterbium-holmium tri-doped lithium niobate crystal high-upconversion luminescent material and a method for preparing the same, and aims to solve the technical problems of low luminous efficiency and poor light damage resistance of existing LiNbO3:Ho crystal. The zirconium-ytterbium-holmium tri-doped lithium niobate crystal high-upconversion luminescent material is made of Li2CO3, Nb2O5, ZrO2, Yb2O3 and Ho2O3. The preparation method includes: weighing, mixing, presintering, seeding, shoulder expanding, isometric growing and crystal polarizing, so that the zirconium-ytterbium-holmium tri-doped lithium niobate crystal high-upconversion luminescent material can be obtained. The light damage resistance of the crystal is greatly improved when 2mol%-6mol% ZrO is doped in the zirconium-ytterbium-holmium tri-doped lithium niobate crystal high-upconversion luminescent material, and improved by three orders of magnitude as compared with that of crystal with 0mol% ZrO doped, and the upconversion luminescence intensity of the doped crystal is gradually improved along with increase of Zr ionic concentration.

The invention provides a preparation method of p-type and n-type conductive lithium niobate nanowires. The preparation method comprises the following steps: step 1, uniformly heating a multi-domain lithium niobate crystal for a certain time by using thermal immobilization technology, and naturally cooling to room temperature, so that protons in the crystal are fixed in a domain wall region; 2, carrying out primary polarization on the prepared lithium niobate crystal by using electric polarization technology; and 3, carrying out secondary polarization on the prepared lithium niobate crystal byutilizing electric polarization technology, so that the conductivity type of nanowires prepared in the step 2 can be changed, and the conversion of p-type and n-type conductive carrier types can be realized through one-time polarization inversion. According to the method, the regulation and control technology of transporting carriers in the lithium niobate crystal at nanoscale is achieved, and theregulation and control problem of the electrical properties of lithium niobate at nanoscale is solved.

The present invention belongs to the field of crystal material technology, and includes mainly setting one support disc inside ceramic crucible, setting one refractory cylinder vertically on the disc, fixing one noble metal ring horizontally on the cylinder, hanging one noble metal cylinder on inner edge of the ring, and making the noble metal crucible rotate around the support shaft and move up and down and the heating winding move up and down with the crucible. During melting material, the noble metal crucible is separated from the noble metal cylinder; and during growing crystal, the noble metal cylinder separates the noble metal crucible into two regions, growth region and melt region. The present invention has the advantages of high material melting efficiency, homogeneous stirring, less volatilization of lithium oxide, easy regulation of temperature field, being favorable to stable crystal growth, etc.

The invention relates to a large-scale silicon-based lithium niobate thin film electro-optic modulator array. The invention has the advantages that the difficulty of preparation process of a lithium niobate crystal layer is reduced through a structural design, the precision requirement of bonding of lithium niobate and silicon is reduced, the preparation and the bonding of a large-scale array typelithium niobate crystal layer can be simultaneously completed at one time, and the production efficiency of the silicon-based lithium niobate thin film electro-optic modulator array is greatly improved; and through the structural design and optimization of the silicon crystal layer, light can be naturally alternated and transmitted mutually in silicon waveguide and lithium niobate waveguide, anda high-performance lithium niobate thin film electro-optic modulation effect is realized. In addition, the method utilizes the maturity advantage of a standardized silicon-based integration technologyand concentrates a complex chip preparation process on the silicon crystal layer, thereby reducing the process error in the chip manufacturing process and ensuring the performance stability of the whole silicon-based lithium niobate thin film electro-optic modulator array.

A Mg-doped lithium niobate crystal with periodically polarized microstructure is prepared frmo Mg-doped lithium niobate powder through growing crystal by Czochralsk method, gas-phase balanced diffusion and low-voltage polarizing at room temp. to make the crystal have periodic structure. It can be used to make optical device. Its advatages are high resistance to optical damage and high uniformity.

The invention discloses a double blended lithium niobate crystal and preparing method in single crystal growth domain, which comprises the following steps: (1) setting component of the crystal as LiaNbbO3:FecCod; setting a as 0. 93800; setting b as 1. 00000; setting c as 0. 00005-0. 00075; setting d as 0. 00005-0. 00050; batching; mixing; calcining; (2) melting; lifting and pulling crystal; (3) proceeding single design; annealing; cutting film; buffing. This invention possesses higher non-volatile storing sensibility, which can be used to canned data, integrated optics and finance aspects.

The invention discloses a silicon dioxide waveguide and lithium niobate film vertically-coupled resonant integrated optical gyroscope. The resonant integrated optical gyroscope comprises a base wafer,a lower coating layer, a silicon dioxide waveguide ring, a silicon dioxide straight waveguide, an upper coating layer, a lithium niobate film, an electric-optic frequency shifter optical waveguide, an electric-optic frequency shifter metal electrode and a lithium niobate straight strip optical waveguide. A light wave passing through electric-optic frequency shifting inside a lithium niobate filmoptical waveguide can be guided into the silicon dioxide waveguide ring along the vertical direction for angular speed measurement; the characteristics, such as low transmission loss and low bending loss, of the silicon dioxide waveguide ring are combined with the electric-optic frequency shifting function of lithium niobate crystal; the problem that an integrated optical frequency shifter is difficult for the integrated optical gyroscope based on the silicon dioxide waveguide to manufacture is overcome, and the problem that the waveguide ring inside the integrated optical gyroscope based on the silicon dioxide waveguide is great in bending loss and excessive in ring semi-diameter is also solved, so that the integration level and practical value of the resonant integrated optical gyroscopeare improved, and the resonant integrated optical gyroscope is applicable for realizing batch production.

The invention discloses a method for manufacturing a near-stoichiometry PPLN all-optical wavelength converter low in Mg doping. The method comprises the steps that firstly, a Z-cut congruent lithium niobate chip with two faces polished is selected, and after the -Z surface of the chip is locally doped with magnesium, a Ti diffusion strip optical waveguide is manufactured on the -Z surface of the chip doped with Mg; secondly, periodical polarization is conducted on the +Z surface of the chip, a periodical array metal optical grating electrode composed of a long aluminum strip is formed, a near-stoichiometry lithium niobate crystal doped with Mg is obtained by means of the rich-lithium VTE technique, and liquid polarization is conducted on the crystal at the indoor temperature by means of a liquid electrode polarization device, so that a periodical crystal superlattice is obtained; finally, the obtained product is doped with Mg, the PPLN crystal is packaged, and near-stoichiometry PPLN all-optical wavelength converter low in Mg doping is obtained. Compared with the prior art, the method has the advantages that cost is low, the use conditions and the application fields of the wavelength converter are widened, the wavelength converter can be integrated with other devices easily, the degree of integration of the devices is improved, coupling losses and transmission losses are greatly reduced, and the system stability is high.