CN112134128A - Ultraviolet laser - Google Patents

Ultraviolet laser Download PDF

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CN112134128A
CN112134128A CN202011030764.7A CN202011030764A CN112134128A CN 112134128 A CN112134128 A CN 112134128A CN 202011030764 A CN202011030764 A CN 202011030764A CN 112134128 A CN112134128 A CN 112134128A
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crystal
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陈慧彬
许凯泽
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Quanzhou Normal University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/091—Processes or apparatus for excitation, e.g. pumping using optical pumping
    • H01S3/094—Processes or apparatus for excitation, e.g. pumping using optical pumping by coherent light
    • H01S3/094038—End pumping
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/05—Construction or shape of optical resonators; Accommodation of active medium therein; Shape of active medium
    • H01S3/06—Construction or shape of active medium
    • H01S3/0602—Crystal lasers or glass lasers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
    • H01S3/106—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity
    • H01S3/108—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating by controlling devices placed within the cavity using non-linear optical devices, e.g. exhibiting Brillouin or Raman scattering
    • H01S3/109—Frequency multiplication, e.g. harmonic generation
    • H01S3/1095—Frequency multiplication, e.g. harmonic generation self doubling, e.g. lasing and frequency doubling by the same active medium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
    • H01S3/16—Solid materials
    • H01S3/163—Solid materials characterised by a crystal matrix
    • H01S3/1666—Solid materials characterised by a crystal matrix borate, carbonate, arsenide

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  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
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  • Nonlinear Science (AREA)
  • Lasers (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)

Abstract

The invention relates to an ultraviolet laser, which comprises a pumping source, a transmission optical fiber, a coupling system, a laser input mirror, a self-frequency doubling laser crystal and a laser output mirror which are sequentially arranged along the same optical axis, wherein the laser input mirror and the laser output mirror form a laser resonant cavity, the self-frequency doubling laser crystal is a Dy: YAB crystal, a pumping light source consisting of the pumping source and the transmission optical fiber is positioned at a focus on one side of the coupling system, the self-frequency doubling laser crystal is positioned at a focus on the other side of the coupling system, the light passing direction of the self-frequency doubling optical crystal is the phase matching direction of the self-frequency doubling of fundamental frequency light, the ultraviolet laser realizes the ultraviolet laser with the wavelength of 287.7nm by LD end face pumping and Dy: YAB self-frequency doubling laser crystal, and can realize the stable output of the ultraviolet laser by only using one self-frequency doubling laser crystal, and has small volume, compact and stable, Stable performance, easy realization and low cost.

Description

Ultraviolet laser
Technical Field
The invention relates to an ultraviolet laser.
Background
The ultraviolet coherent light source has the characteristics of short wave band, high single molecular energy and small facula, and has wide application prospect in the fields of ultrahigh density optical drives, precision material processing, ultraviolet curing, photoetching, optical printing, optical communication, medical treatment and the like. Common ultraviolet lasers utilize the frequency doubling characteristic of nonlinear crystals to perform secondary or multiple frequency conversion, such as frequency doubling and frequency mixing, on fundamental frequency light generated by a pumping source, so that wavelength conversion from visible-band laser and infrared-band laser to ultraviolet-band laser is realized. Taking an ultraviolet laser taking an LBO crystal as a frequency doubling crystal as an example, 1064nm fundamental frequency light emitted by a laser pumping source is frequency doubled by the frequency doubling crystal in non-critical phase matching to obtain 532nm double frequency light, and the 1064nm fundamental frequency light and the 532nm laser obtained by frequency doubling are subjected to sum frequency by the frequency tripling crystal to obtain 355nm ultraviolet laser output. In the process, the conversion efficiency of the frequency tripling laser is influenced by the polarization state of the frequency doubled and fundamental frequency light, the light spot walk-off and other optical characteristics, so that the high-efficiency ultraviolet laser is difficult to obtain. In order to obtain higher conversion efficiency, more optical elements are inevitably introduced into the system, so that the system structure is more complicated, the difficulty and the requirement of optical path debugging are increased, and the manufacturing cost of the laser is increased.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a novel ultraviolet laser.
The ultraviolet laser comprises a pumping source, a transmission optical fiber, a coupling system, a laser input mirror, a self-frequency-doubling laser crystal and a laser output mirror which are sequentially arranged along the same optical axis, wherein the laser input mirror and the laser output mirror form a laser resonant cavity, the self-frequency-doubling laser crystal is a Dy: YAB crystal, a pumping light source formed by the pumping source and the transmission optical fiber is positioned at a focus on one side of the coupling system, the self-frequency-doubling laser crystal is positioned at a focus on the other side of the coupling system, the laser input mirror and the laser output mirror are plane mirrors, and the light passing direction of the self-frequency-doubling optical crystal is the phase matching direction of the self-frequency doubling of the fundamental light.
Furthermore, the pump source is a blue LD pump source, and the pump wavelength range is 460 and 480 nm.
Further, the self-frequency-doubling optical crystal is cut along the phase matching direction of the fundamental frequency light by 56-58 degrees.
Furthermore, the light incident side surface of the laser input mirror is plated with an antireflection film for 460-480nm band laser, and the light emergent side surface of the laser input mirror is sequentially plated with an antireflection film for 460-480nm band laser, a high reflection film for 560-600nm band laser and a high reflection film for 280-300nm band laser.
Furthermore, a high-reflection film which is highly transparent to the light with the wavelength of 280-300nm and highly reflective to the laser with the wavelength of 560-600nm is plated on the light incident side surface of the laser output mirror.
Furthermore, a dielectric film which is highly transparent to the laser with the wavelength of at least 280-once 300nm, 480-once 460-once and 600-once 560-once is plated on the light incident side surface of the self-frequency doubling laser crystal, and a dielectric film which is highly transparent to the laser with the wavelength of at least 280-once 300nm, 560-once and 600-once is plated on the light emergent side surface of the self-frequency doubling laser crystal.
Furthermore, the materials of the laser input mirror and the laser output mirror are CaF2。
Further, the length of the self-frequency doubling optical crystal is 1-30 mm.
Compared with the prior art, the invention has the following beneficial effects: the end-pumped LD laser and the YAB self-frequency-doubling laser crystal with Dy being YAB can realize the ultraviolet laser with the wavelength of 287.7nm, only one self-frequency-doubling laser crystal is needed to realize the stable output of the ultraviolet laser, and the laser has the advantages of small volume, compact and stable structure, high output power, high conversion efficiency, stable performance, easy realization and low cost, and is suitable for industrial production and application.
Drawings
The invention is further described with reference to the following figures.
FIG. 1 is a block diagram of an example UV laser;
fig. 2 shows Dy: effective nonlinear coefficient (| d) of YAB crystaleff| with matching angle (theta)m) The variation curve of (d);
fig. 3 shows Dy: YAB Crystal match Angle (θ)m，φm) A fitted curve that varies with the wavelength of the fundamental light.
In the figure: 1-a pump source; 2-a transmission fiber; 3-a coupled system; 301-plano-convex collimating mirror; 302-plano-convex focusing lens; 4-a laser input mirror; 5-self-frequency-doubling laser crystal; 6-laser output mirror.
Detailed Description
The invention is further described with reference to the following figures and detailed description.
Description of terms:
high transmittance: means that the reflectance (R) for light of a particular wavelength or band of wavelengths is greater than 99%;
high reflection: means a transmittance (T) of greater than 99% for light of a particular wavelength or band;
phase matching: the physical essence of the nonlinear optical device is that the phase surface of fundamental frequency light and frequency doubling light propagating to the crystal exit surface is an equiphase surface. Experiments prove that when fundamental frequency light is at a certain specific angle (theta)m，φm) When the crystal is incident, good frequency doubling effect can be obtained, and when the crystal is incident at other angles (theta, phi), the frequency doubling effect is very poor, even frequency doubling light output cannot be observed. According to the phase matching condition omega1n1+ω2n2=ω3n3The corresponding fundamental frequency light (omega) can be solved1) Phase matching angle (theta)m，φm）。
Effective nonlinear optical coefficient (d)eff）：deffThe essence of the conversion in frequency is when deffThe larger the value of | is, the higher the efficiency of generating the second harmonic (frequency doubled light). deffThe value is limited by the value of (theta, phi), and under the condition of phase matching of fundamental light and frequency doubling light, (theta, phi) = (theta, phi)m，φm) Angle (theta) is recordedM，φM) When the phase of the fundamental light and the phase of the frequency doubling light are matched, | deff | obtains the direction angle of the maximum value.
As shown in fig. 1, an ultraviolet laser includes a pumping source 2, a transmission fiber 2, a coupling system 3, a laser input mirror 4, a self-frequency doubling laser crystal 5, and a laser output mirror 6, which are sequentially arranged along a same optical axis, wherein the fiber coupling system is composed of the transmission fiber 2 and the coupling system 3; the laser is used for transmittingThe laser resonator is composed of an input mirror and a laser output mirror, and the self-frequency-doubling laser crystal is rare-earth ion Dy3+The ion-doped, oxide-based self-frequency-doubling laser crystal is preferably Dy: YAB crystal (Dy: YAl (BO: YAl))3)4、Crystal), the pump light source that pump source and transmission fiber constitute is located the focus of coupled system one side, and self-frequency doubling laser crystal is located the focus of coupled system opposite side, laser input mirror, laser output mirror are the level crossing, and the light direction of passing through from frequency doubling optical crystal is the phase place matching direction of fundamental frequency light self-frequency doubling.
In this embodiment, the coupling system includes a plano-convex collimating lens 301 and a plano-convex focusing lens 302 sequentially disposed along the same optical axis.
In this example, Dy3+The ion doping amount accounts for one thousandth to ten percent of the total volume of the optical crystal.
In this example, the rare earth ion Dy3+The ion-doped laser crystal is the most potential candidate for directly obtaining yellow laser at present, and Dy3+The self-frequency-doubling laser crystal with the substrate of ion doping and oxide has a large emission cross section in a yellow light wave band. The self-frequency-doubling laser crystal is a Dy-YAB crystal. YAB crystal has yellow light output level near 473nm wavelength4F9/2Has an absorption cross section of 1.342X 10-21cm2(ii) a Rare earth ion Dy3+After absorbing 473nm pump light, it can excite the pump light from the upper energy level4F9/2To a lower energy level6H13/2Thereby generating 575.5nm yellow fluorescence.
In this embodiment, the pump source is a blue LD pump source with a center wavelength of 473nm, so that the absorption efficiency of the self-frequency doubling laser crystal Dy: YAB for pump light is increased, thereby improving the output power of the fundamental light.
In this embodiment, the self-doubling optical crystal is cut 56-58 °, preferably 57 °. 58', along the phase matching direction of the fundamental light.
In this embodiment, the light incident side of the laser input mirror is plated with an antireflection film for 460-plus-480 nm band laser, the light exit side of the laser input mirror is sequentially plated with an antireflection film for 460-plus-480 nm band laser, a high reflection film for 560-plus-600 nm band laser, and a high reflection film for 280-plus-300 nm band laser, and the light incident side of the laser output mirror is plated with a high reflection film for 280-plus-300 nm band laser and for 560-plus-600 nm band laser, so that the loss of the resonant cavity to the pump light is reduced through the mirror coating, the absorption rate of the self-frequency doubling crystal to the pump light is increased, and the gain of the system to the output of ultraviolet laser is improved.
In this embodiment, the light incident side of the self-frequency-doubling laser crystal is plated with a dielectric film that is highly transparent to the laser light with the wavelength of at least 280-. The conversion efficiency and the output power of the laser are increased by coating the light-transmitting end face of the self-frequency-doubling laser crystal.
In this embodiment, the materials of the laser input mirror and the laser output mirror are all CaF2。
In this embodiment, the self-frequency doubling crystal adopts, but is not limited to, a critical phase matching method.
Preferably, the light passing direction of the self-frequency-doubling optical crystal is the phase matching direction of the self-frequency doubling of the fundamental frequency light, namely, the effective nonlinear coefficient (d) along the crystal non-principal planeeff) Maximum direction, i.e. along angle (theta)M，φM) Cutting;
YAB phase matching mode of self-frequency-doubling laser crystal Dy is I-type critical phase matching. Based on the refractive index curved surface equation of the self-frequency doubling crystal by using the phase matching theory
Figure DEST_PATH_IMAGE002
(1) (where θ is the angle between wave vector k and z-axis, φ is the angle between the X-axis and the mapping of wave vector k on crystal XY plane, n is the refractive index of light wave, n isx，ny，nzCrystal principal refractive index), the refractive index equation is considered to be a one-dimensional quadratic equation with respect to n.
Derived from the root-finding formula
Figure DEST_PATH_IMAGE004
(2) Wherein "+" denotes a fast light with a small refractive index and is denoted as n (e)2) And "-" indicates that slow light having a large refractive index is denoted as n (e)1)。
And then the I-type phase matching condition under frequency multiplication is adopted: n is1(e1)=n2(e2) (3) in which n1(e1) Slow light refractive index of fundamental frequency light, n2(e2) Is the fast optical refractive index of the frequency doubled light.
The phase matching angle (theta) of the fundamental light and the frequency doubling light of the self-frequency doubling crystal can be obtained by simultaneous formulas (1), (2) and (3)m，φm). Because the refractive index equation of the biaxial self-frequency doubling crystal is in an ellipsoid curved surface shape and is relatively complex, the critical phase matching angle (theta) is difficult to obtainm，φm) So that the range of theta and phi is controlled in the first quadrant by a point-by-point scanning method by using Matlab software programming, and the matching angles of other quadrants can be converted from the matching angle of the first quadrant. Therefore, only the critical phase matching angle (theta) of the biaxial self-frequency doubling crystal in the first quadrant needs to be solvedm，φm) The approximate solution of the phase matching angle can obtain the class I phase matching angle of the biaxial self-frequency doubling crystal.
Then will solve the obtained (theta)m，φm) Substituting into the solving equation of effective nonlinear optical coefficient of self-frequency doubling crystal to solve | deffAngle at which | takes the maximum value (θ)M，φM). Because the effective nonlinear coefficient of Dy: YAB crystal is mainly influenced by d in the XZ plane11YAB crystal is simplified here to solve its solution for | d in the XZ principal planeeff|（cosθm) Solving the obtained | deffMatching angle theta corresponding to the maximum value |mIs the optimum light passing direction theta of the crystalMTherefore Dy: YAB is self-frequency-doubling crystal with light-passing direction (theta)M，φM) Is (57 degrees, 58', 0 degrees)
Referring to FIG. 3, the refractive index of the crystalThe angle θ =57 °. 58' in the direction of the largest principal axis (z axis) and phi =0 ° in the direction of the smallest principal axis (x axis) of the refractive index of the crystal. In the three-wave interaction angle phase matching of the uniaxial crystal,
Figure DEST_PATH_IMAGE006
on both sides respectively have
Figure DEST_PATH_IMAGE008
The maximum allowable mismatch amount
Figure DEST_PATH_IMAGE010
To determine the permissible parameters of phase matching
Figure DEST_PATH_IMAGE012
Balance of
Figure 723965DEST_PATH_IMAGE012
Is the allowable angle of the frequency doubling crystal. The allowable angle is one of the important parameters describing the ease with which the frequency doubling crystal can achieve phase matching.
To pair
Figure 703422DEST_PATH_IMAGE010
In that
Figure DEST_PATH_IMAGE014
θMThe following formula can be obtained by performing Taylor expansion nearby
Figure DEST_PATH_IMAGE016
（3）
Calculated by the formula (3), Dy: YAB when the fundamental frequency light is 575.5nm
Figure 828634DEST_PATH_IMAGE012
About 250 mrad =14 °. 19', which indicates that Dy: YAB crystal has a large allowable angle, and phase matching is easily achieved. Therefore, the light passing direction (theta) of the Dy: YAB self-frequency doubling crystal is selectedM，φM) Is (57 DEG, 58' + -2 DEG, 0 DEG), i.e. has the largest main refractive index with the crystalThe angle θ =57 °. 58' ± 2 ° in the axial (z-axis) direction, and φ =0 ° in the direction of the principal axis of minimum refractive index (x-axis) of the crystal.
Because of Dy doping3+The absorption cross section of the laser crystal is small and is about 10-21cm2The magnitude, so the length of the crystal sample needs to reach the centimeter scale to ensure the energy absorption of the laser output, and the crystal length range of the self-frequency doubling laser crystal Dy: YAB is 10-30 mm. Further consider the walk-off effect of the fundamental light and the frequency doubled light. When the phase matching of the fundamental frequency light is realized, the polarization state of the light beam participating in the nonlinear transformation influences the coincidence condition of the light ray direction S and the wave vector K of the light beam, and the included angle between the light ray S and the wave vector K of the light beam is called as a walk-off angle α. Because the walk-off effect of the light in the frequency doubling crystal becomes more and more obvious as the propagation wavelength of the light becomes shorter, the influence on the frequency doubling efficiency becomes more and more serious. Therefore, when frequency conversion is carried out in the ultraviolet band, the calculation problem of the walk-off angle of the frequency doubling crystal is particularly required to be considered. In the uniaxial crystal, the walk-off angle of the ordinary ray o is zero, and the walk-off angle of the extraordinary ray e can be calculated by the following formula
Figure DEST_PATH_IMAGE018
（4）
Since the self-frequency-doubling laser crystal Dy: YAB is a negative uniaxial crystal adopting I-type critical phase matching (o + o → e), the walk-off angle of 575.5nm of fundamental frequency light (o light) is 0, and the walk-off angle of 287.75nm of frequency doubling light (e light) is 2 DEG.25', the influence of the walk-off effect of the frequency doubling crystal on the frequency doubling efficiency needs to be considered. The interaction length (pore diameter length) of the crystal was 9.33mm as determined from the walk-off angle of the crystal. The maximum conversion efficiency that is desirable when L = T is therefore based on the fact that the length of the crystal is periodically distributed with a frequency-doubled conversion efficiency
Figure DEST_PATH_IMAGE020
The optimum length of the crystal L = T =11.17mm can be obtained from the relationship. Although a longer crystal length can bring higher frequency doubling efficiency, the influence on the spot distribution of frequency doubling light is more serious when the crystal length is longer due to the walk-off effectTherefore, the crystal length of Dy: YAB is selected to be 9-11mm in comprehensive consideration.
One specific example is given below:
in this embodiment, the ultraviolet laser includes an LD blue light pump source, a transmission fiber, a coupling system, a laser input mirror, a self-frequency doubling laser crystal, and a laser output mirror, which are sequentially disposed on the same optical axis, wherein pump light with a central wavelength of 473nm of the LD blue light pump source is output through fiber coupling, and the LD pump light is vertically incident into the self-frequency doubling laser crystal input mirror and the output mirror are CaF which is transparent to ultraviolet light through the coupling system2A plane mirror as substrate, wherein the light incident surface of the laser input mirror is coated with a high-transmittance film (HT @473 nm) for pumping light at 473nm wavelength, and the light emergent surface is coated with a high-reflection film (HR @575.5 nm) for fundamental frequency light at 575.5nm wavelength and frequency doubling light at 287.7nm wavelength&287.7 nm); the light incident surface of the laser output mirror is plated with high transmittance (HT @287.7 nm) for frequency doubling light with the wavelength of 287.7nm and high reflectance (HR @575.5 nm) for fundamental frequency light with the wavelength of 575.5 nm; the self-frequency doubling crystal is I-class matched Dy3+The YAB self-frequency doubling crystal doped with rare earth ions has a phase matching angle of (57 degrees, 58' +/-2 degrees, 0 degrees (refer to figure 3), and an effective nonlinear optical coefficient deff=0.9104 pmV-1(cf. FIG. 2), the crystal size is 4X 10 mm; the crystal light incident end surface is coated with a film which is highly transparent to 473nm pump light, 575.5nm fundamental frequency light and 287.7nm frequency doubling light (HT @473 nm)&575.5nm&287.7 nm), the coating film on the light emergent end face has high transmittance to 575.5nm fundamental frequency light and 287.7nm frequency doubling light (HT @575.5 nm)&287.7nm）。
In this embodiment, a straight-type planar-planar resonant cavity is adopted, and the working process is as follows:
firstly, 473nm laser generated by a blue LD pumping source pumps Dy (YAB) crystal and Dy after passing through an optical fiber coupling system3+Dy excited by absorbed 473n pump light3+From4F9/2Transition of upper energy level to6H13/2The lower energy level generates 575.5nm fluorescence, and the fluorescence is oscillated and enhanced between the laser input mirror and the laser output mirror to form 575.5nm fundamental laser; then utilizing the frequency doubling property of the Dy: YAB self-frequency-doubling laser crystal subjected to I-type phase matching to carry out frequency doubling on the generated 575.5nm yellow fundamental frequency light to obtain a central waveAn ultraviolet laser output of 287.7nm in length.
The laser can realize stable output of ultraviolet laser by only using one self-frequency-doubling laser crystal, fundamentally solves the stability problem of all-solid-state frequency-doubling ultraviolet laser, and breaks through the system structure of the existing ultraviolet laser which at least needs two crystals.
Because the conversion efficiency of the frequency tripling laser is influenced by the optical characteristics of the polarization state, the spot walk-off and the like of the frequency doubled and fundamental frequency light, and two or even a plurality of laser crystals are used in the common all-solid-state ultraviolet laser, the conversion efficiency of the frequency tripling laser is not only limited by the optical characteristics of the fundamental frequency light generated by the laser crystals but also by the optical characteristics of the frequency doubled light output by the frequency doubled crystals. The laser only uses one self-frequency-doubling laser crystal, and compared with the conversion efficiency influence factor dimension of common ultraviolet laser triple-frequency laser, the laser greatly reduces the difficulty of laser system light path debugging and laser production, and reduces the production cost.
The laser uses Dy3+ as doping ion and oxide as substrate. Dy3+ laser material is the most potential one for directly acquiring yellow laser at present. Rare earth ions (Pr, Er, Ho, etc.) in the visible wavelength band which are common rarely have a yellow emission cross section in the wavelength band around 575.5nm, Dy3+ has an emission cross section in the order of 10-21 cm2 in this wavelength band, and the emission cross section can reach the order of 10-20 cm2 when an oxide is selected as a substrate. The self-frequency-doubling laser crystal with the base of Dy3+ doped oxide can obtain higher ultraviolet laser output and lower laser threshold.
YAB crystal adopted by the laser is negative uniaxial crystal, and the phase matching condition is only related to theta and is not related to phi; the large allowable angle exists in the 575.5nm fundamental frequency optical band, the phase matching is easy to realize, and the debugging difficulty of the optical path is further reduced. And the effective linear coefficient of YAB is 3.9 times of KDP, which can bring higher frequency doubling efficiency, laser output and lower laser threshold.
The laser can obtain higher ultraviolet laser conversion efficiency, greatly reduces the complexity of an ultraviolet laser system, reduces the light path debugging and production difficulty of the laser system, has simple and compact structure, stable output laser power and low laser threshold, is suitable for industrial production and application, and is easy to produce, debug and produce in batches.
If this patent discloses or refers to parts or structures that are fixedly connected to each other, the fixedly connected may be understood as: a detachable fixed connection (for example using a bolt or screw connection) can also be understood as: non-detachable fixed connections (e.g. riveting, welding), but of course, fixed connections to each other may also be replaced by one-piece structures (e.g. manufactured integrally using a casting process) (unless it is obviously impossible to use an integral forming process).
In the description of this patent, it is to be understood that the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the patent, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the patent.
The above-mentioned preferred embodiments, further illustrating the objects, technical solutions and advantages of the present invention, should be understood that the above-mentioned are only preferred embodiments of the present invention and should not be construed as limiting the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (4)

1. An ultraviolet laser, characterized by: the self-frequency doubling laser crystal is a Dy: YAB crystal, a pumping light source consisting of the pumping source and the transmission optical fiber is positioned at a focus on one side of the coupling system, the self-frequency doubling laser crystal is positioned at a focus on the other side of the coupling system, and the light passing direction of the self-frequency doubling optical crystal is the phase matching direction of self-frequency doubling of the fundamental frequency light.
2. The uv laser of claim 1, wherein: the pumping source is a blue LD pumping source, and the pumping wavelength range is 460 and 480 nm.
3. The uv laser of claim 1, wherein: the self-frequency doubling optical crystal is cut along the phase matching direction of the fundamental frequency light by 56-58 degrees.
4. The uv laser of claim 1, wherein: the length range of the self-frequency doubling optical crystal is 1-30 mm.
CN202011030764.7A 2020-09-27 2020-09-27 Ultraviolet laser Pending CN112134128A (en)

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