Three-point temperature compensation 473nm blue continuous laser

Abstract

A three-point temperature compensated 473nm blue continuous laser, which consists of four parts: a pump source and a pump coupling part, a resonant cavity and an intracavity frequency doubling part, an output beam shaping part, and a three-point temperature compensation temperature control part. It can provide the necessary blue light monochromatic reference light source for applications such as spectral analysis, biological analysis, and three-primary color matching. The 473nm blue laser can continuously output 473nm blue laser, with an output power greater than 1W, a power stability better than 1%, a light-to-light conversion efficiency from pump light to output light greater than 18%, an output beam diameter of 10mm, a divergence angle less than 0.05mrad, and an output wavefront PV less than λ / 3.

Description

Technical Field

[0001] The present invention relates to a 473nm blue continuous laser, in particular to a three-point temperature compensated 473nm blue continuous laser, and more specifically to a blue monochromatic reference light source that can be used for spectral analysis, biological analysis, three-primary color matching, etc. Background Art

[0002] 473nm blue light continuous output semiconductor pumped solid-state lasers are widely used in the fields of spectral analysis, bioanalysis, and three-primary color matching. With the rapid development of analytical testing technology and three-primary color matching technology, the use of high-brightness pure-color blue lasers in the 473nm band as the reference light source for systems such as spectral analysis, bioanalysis, and three-primary color matching, and the development of technical research in related fields have attracted more and more attention. In recent years, the research on how to use semiconductor laser pumping to obtain stable and efficient 473nm pure-color blue laser output has become one of the hot research topics in the laser field.

[0003] In various fields such as spectral analysis, biological analysis, and three-primary color matching, a large number of 473nm high-brightness blue lasers are needed as reference light sources. Therefore, the research and development of 473nm blue lasers at home and abroad have been carried out for nearly 20 years, and various products have been formed on the market. However, since the 473nm band is obtained by frequency doubling the 946nm fundamental frequency, and the 946nm fundamental frequency is a quasi-three-level structure, the fundamental frequency and frequency doubling efficiency are very low. At present, the light-to-light conversion efficiency of 473nm lasers reported at home and abroad is about 10%. Occasionally, laboratory research reports have only increased by 2-3%, and the overall efficiency is less than 13%. Due to the low conversion efficiency, the only way to obtain high-power output is to increase the pump energy, and the increase in pump energy will bring a series of problems, such as increased output power of the pump source, increased drive current, complex drive and temperature control systems, prominent thermal effects, reduced conversion efficiency and increased overall volume, etc. More importantly, the above problems also bring about increased costs and reduced output stability. In recent years, when using 473nm high-brightness blue laser as a monochromatic reference light source, higher and clearer requirements have been put forward for the output beam quality. At present, the research on 473nm blue laser is mainly focused on improving efficiency and output stability, which is mainly solved by optimizing the optical resonance system. However, there are few reports on the research that combines multi-point temperature compensation, resonant cavity design and output optical shaping system design to solve the above problems. Summary of the invention

[0004] The purpose of the present invention is to provide a three-point temperature compensated 473nm blue light continuous laser for applications such as spectral analysis, biological analysis, and three-primary color matching. The laser can continuously output 473nm blue laser, the output power is greater than 1W, the power stability is better than 1%, the light-to-light conversion efficiency from pump light to output light is greater than 18%, the output beam diameter is 10mm, the divergence angle is less than 0.05mrad, and the output wavefront PV is less than λ / 3.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] A three-point temperature-compensated 473nm blue continuous laser is characterized in that it includes a pump source semiconductor laser, and along the laser output direction of the semiconductor laser are cylindrical fast-axis compression microlens, aspheric coupling focusing lens, plano-concave back cavity mirror, dielectric crystal, frequency doubling crystal, planar output cavity mirror, double concave shaping beam expansion lens and double-cemented collimating output lens:

[0007] The positive electrode of the semiconductor laser is fixed on one end of the upper surface of the first heat sink, and the other end of the upper surface of the first heat sink is fixed with a pump source negative electrode connecting plate through an insulating material, and the negative electrode of the pump source is connected to the negative electrode connecting plate through a negative electrode lead. The lower surface of the first heat sink is in contact with the temperature control surface of the first semiconductor refrigerator, and the other surface of the first semiconductor refrigerator is in contact with the bottom plate of the heat dissipation shell of the laser; the first heat sink, the first temperature sensor, the first semiconductor refrigerator, the bottom plate of the shell and the third temperature acquisition and control system constitute a pump source working temperature compensation control component, which collects and controls the working temperature of the semiconductor laser so that its output wavelength works at the maximum absorption peak of the dielectric crystal;

[0008] The dielectric crystal is installed in the through hole in the middle of the second heat sink, the inner wall of the heat sink through hole is in contact with the four sides of the dielectric crystal, the bottom surface of the second heat sink is in contact with the temperature control surface of the second semiconductor refrigerator, the other side of the second semiconductor refrigerator is in contact with the bottom plate of the whole machine housing, and the second temperature sensor is installed inside the second heat sink; the second heat sink, the second temperature sensor, the second semiconductor refrigerator, the bottom plate of the housing and the second temperature acquisition and control system constitute a dielectric crystal working temperature compensation control component, which collects and controls the working temperature of the dielectric crystal so that it can stably work at the selected temperature point;

[0009] The frequency doubling crystal is installed in the middle through hole of the third heat sink, the inner wall of the heat sink is fitted with the four sides of the frequency doubling crystal, the bottom surface of the third heat sink is fitted with the temperature control surface of the third semiconductor refrigerator, the other side of the third semiconductor refrigerator is fitted with the bottom plate of the whole machine shell, and the third temperature sensor is installed inside the third heat sink; the third heat sink, the third temperature sensor, the third semiconductor refrigerator, the bottom plate of the shell and the third temperature acquisition and control system constitute the working temperature compensation control component of the frequency doubling crystal, collect and adjust the working temperature of the frequency doubling crystal, so that its frequency doubling efficiency is the highest, and it works stably at the matching temperature point;

[0010] The light emitting surface of the semiconductor laser is glued to the cylindrical fast axis compression microlens;

[0011] The concave curvature of the plano-concave rear cavity mirror matches the focal length of the thermal effect lens of the dielectric crystal, and together they eliminate the phase difference of the oscillation fundamental frequency light, so that the beam waist of the oscillation fundamental frequency light is located on the inner surface of the planar output cavity mirror;

[0012] The semiconductor laser outputs pump light to pump the dielectric crystal, which is excited to produce a quasi-three-level fundamental frequency 946nm laser, which is inserted into the cavity through a frequency doubling crystal to form a 473nm frequency-doubled high-brightness blue laser, which is output through the planar output cavity mirror and passes through the double concave shaping beam expansion lens and the double-glued collimating output lens to form an output light with a wavefront reaching one-third of the wavelength.

[0013] The technical effects of the present invention are as follows:

[0014] 1. The fundamental frequency light of the present invention is formed by inserting a frequency doubling crystal into the cavity to form a 473nm frequency doubling high brightness blue laser that is output through the output cavity mirror. The output frequency doubling beam has the same characteristics as the fundamental frequency light beam in the cavity. According to the laser cavity parameters, a double concave shaping beam expansion lens is matched after the output light passes through the output mirror. After the output light passes through the shaping beam expansion lens, it passes through the double-cemented collimating output lens to form an output light with a wavefront reaching one-third of the wavelength.

[0015] 2. The three-point temperature compensation and temperature control part consists of the pump source working temperature point compensation and control component, the dielectric crystal working temperature point compensation and control component, the frequency doubling crystal working temperature point control component and the temperature acquisition and control system. The working temperatures of the three devices are compensated and controlled at their respective temperature points through the temperature acquisition and control system, so that the laser output light conversion efficiency reaches more than 18%, and the output power stability is better than 1%. The pump source compensation temperature control component uses the characteristic that the output wavelength of the 808nm band semiconductor laser changes by 0.3nm when the temperature changes by 1℃. The pump source compensation temperature control component controls its working temperature through the pump source compensation temperature control component so that its output wavelength works at the maximum absorption peak of the dielectric crystal. The dielectric crystal working temperature is controlled by the dielectric crystal compensation temperature control component so that it works stably at the selected temperature point, so that the focal length of the thermal lens generated by the dielectric crystal is stable and matches the concave curvature of the plano-concave rear cavity mirror, eliminating the resonant fundamental frequency optical aberration. The frequency doubling crystal compensation temperature control component uses the frequency doubling characteristics of the frequency doubling crystal temperature matching to adjust the frequency doubling crystal working temperature so that its frequency doubling efficiency is the highest and it works stably at the matching temperature point.

[0016] 3. The present invention can continuously output 473nm blue laser, with an output power greater than 1W, a power stability better than 1%, a light-to-light conversion efficiency from pump light to output light greater than 18%, an output beam diameter of 10mm, a divergence angle less than 0.05mrad, and an output wavefront PV less than λ / 3. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the three-point temperature compensation 473nm blue continuous laser system diagram of the present invention DETAILED DESCRIPTION

[0018] The present invention will be described in detail below in conjunction with the accompanying drawings, but this should not limit the protection scope of the present invention.

[0019] Please refer to Figure 1 , Figure 1 The figure shows the system diagram of the three-point temperature compensated 473nm blue continuous laser of the present invention. As can be seen from the figure, the three-point temperature compensated 473nm blue continuous laser of the present invention is composed of four parts: pump source and pump coupling part, resonant cavity and intracavity frequency doubling part, output beam shaping part and three-point temperature compensation temperature control part.

[0020] Figure 1In the figure, the pump source semiconductor laser 03 is a single-tube semiconductor laser in the 808nm band, with a maximum output power of 6W and a light-emitting area of ​​400μm×2μm. The positive electrode 032 of the pump source semiconductor laser is fixed to one end of the upper surface of the copper heat sink 13, and the pump source light-emitting surface faces the direction of the laser cavity. The other end of the upper surface of the copper heat sink 13 of the pump source is fixed to the pump source negative electrode connecting plate 01 through the insulating material 02, and the negative electrode of the pump source is connected to the negative electrode connecting plate 01 through the negative electrode lead 031. The lower surface of the heat sink 13 is in contact with the temperature control surface of the pump source compensation temperature control semiconductor refrigerator 15, and the other side of the semiconductor refrigerator 15 is in contact with the bottom plate 22 of the laser heat dissipation housing. The pump source working temperature test sensor 14 is embedded in the middle part of the heat sink 13. The pump source semiconductor laser 03, the heat sink 13, the negative electrode connecting plate 02, the pump source compensation temperature control semiconductor refrigerator 15, the pump source working temperature sensor 14 and the heat dissipation bottom plate 22 of the whole machine shell together constitute the pump source part. The pump source semiconductor laser 03 is glued with a cylindrical fast axis compression microlens 04 on the light emitting surface facing the laser cavity. After the pump light passes through the cylindrical compression microlens 04, it passes through the aspheric coupling focusing lens 05 forward. The position of the coupling focusing lens 05 is adjusted forward and backward along the optical axis of the pump light, so that the pump light passes through the rear cavity mirror 06 and is focused at a position 1mm away from the rear surface inside the dielectric crystal 07. The cylindrical fast axis compression microlens 04 uses a quartz cylindrical optical fiber with a diameter of 400μm, and the surface is coated with an anti-reflection film in the 805-810nm band. The aspheric coupling focusing lens 05 has a convex spherical surface facing the pump source and a quadratic hyperboloid facing the laser cavity. Both sides are coated with an anti-reflection film in the 805-810nm band.

[0021] The resonant cavity and the intracavity frequency doubling part are composed of a plano-concave rear cavity mirror 06, a dielectric crystal 07, a frequency doubling crystal 08 and a plane output mirror 09. The components of the resonant cavity are arranged in sequence along the optical axis to form a plano-concave linear intracavity frequency doubling structure. The arrangement relationship is as follows: after the pump light passes through the coupling focusing mirror 05, it passes forward through the plane of the resonant cavity plano-concave rear cavity mirror 06, passes forward through the concave surface of the plano-concave rear cavity mirror, passes through the rear surface of the dielectric crystal 07, and is focused at a distance of 1mm from the rear surface. After focusing, the pump light diverges and then reaches the front surface of the dielectric crystal 07, and is reflected back into the dielectric crystal by the reflective film on the front surface. The plano-concave rear cavity mirror 06 is made of fused quartz material, with a diameter of 10mm and a center thickness of 2mm. The side facing the pump source 03 is a flat surface coated with an 805-810nm band anti-reflection film, and the side facing the dielectric crystal 07 is a concave spherical surface with a curvature radius of 70mm. The concave surface is also coated with an 805-810nm band anti-reflection film and a 946nm total reflection film. The dielectric crystal 07 is made of Nd:YAG material, with a size of 3×3×3mm, a Nd doping concentration of 1%, a smooth surface facing the rear cavity mirror 06, a distance of 3mm from the center point of the concave surface of the rear cavity mirror 06, and coated with 805-810nm band and 946nm band anti-reflection film. The side of the dielectric crystal 07 facing the frequency doubling crystal 08 is also a smooth surface, and is coated with a total reflection film of 805-810nm band and a 946nm anti-reflection film at the same time. The other four surfaces of the dielectric crystal 07 are rough and uncoated. The dielectric crystal 07 is installed in the square through hole in the middle of the dielectric crystal copper heat sink 16. The through hole size is the same as the outer size of the dielectric crystal 07, and the inner wall is fitted with the four sides of the dielectric crystal 07. The bottom surface of the copper dielectric crystal heat sink 16 is fitted with the temperature control surface of the compensation temperature control semiconductor refrigerator 18, and the other side of the dielectric crystal compensation temperature control semiconductor refrigerator 18 is fitted with the bottom plate 22 of the whole machine shell. The dielectric crystal 07 operating temperature sensor 17 is installed inside the copper heat sink 16 on the lower side of the dielectric crystal 07. The frequency doubling crystal 08 adopts a second-class matching BiBO crystal with a size of 2×2×10mm. The side facing the dielectric crystal is a smooth surface, 5mm away from the front surface of the dielectric crystal 07, and is coated with a 946nm anti-reflection film and a 473nm total reflection film. The side of the frequency doubling crystal 08 facing the output mirror 09 is also a smooth surface, 3mm away from the output cavity mirror 09, and is coated with 946nm and 473nm anti-reflection films. The other four surfaces of the frequency doubling crystal 08 are rough and uncoated. The frequency doubling crystal 08 with the same structure is installed in the through hole in the middle of its copper heat sink 19. The through hole size is the same as the external size of the frequency doubling crystal 08, and the inner wall fits the four sides of the frequency doubling crystal 08. The bottom surface of the copper frequency doubling crystal heat sink 19 is in contact with the temperature control surface of the compensation temperature control semiconductor refrigerator 21, and the other side of the frequency doubling crystal 08 compensation temperature control semiconductor refrigerator 21 is also in contact with the bottom plate 22 of the whole machine housing. The frequency doubling crystal 08 working temperature sensor 20 is installed inside the copper heat sink 19 on the lower side of the frequency doubling crystal 08.The output mirror 09 is made of fused quartz material, with a diameter of 10 mm and two flat surfaces. The rear surface facing the frequency doubling crystal 08 is coated with a 946nm total reflection film and a 473nm anti-reflection film. The other surface of the output mirror 09 is the laser output surface coated with a 473nm anti-reflection film.

[0022] The 473nm high-brightness blue laser is output through the output mirror 09. The characteristics of the 473nm frequency-doubled output beam are consistent with those of the 946nm fundamental frequency light beam. After focusing at the beam waist on the inner cavity surface of the output mirror 09, it is output with beam characteristics matching the cavity parameters. The output light beam parameters can be calculated by combining the equivalent thermal lens when the plano-concave rear cavity mirror 06 and the dielectric crystal 08 are working, the optical path of the frequency-doubled crystal 08, and the optical path of the output mirror 09. A shaping beam expander lens 10 with concave surfaces on both sides is placed 3mm in front of the output mirror 09. The shaping beam expander lens 10 is made of fused quartz material, with a double-sided curvature radius of 2.54mm, a diameter of 5mm, a center thickness of 1.3mm, and a 473nm anti-reflection film is coated on both sides. A collimating output lens group is placed 15.6mm behind the shaping and expanding lens 10, and is formed by gluing a biconvex lens 11 and a concave-convex lens 12. The biconvex lens 11 is coated with a 473nm anti-reflection film on one side facing the shaping and expanding lens 10, and the other side is not coated and is glued to the concave surface of the concave-convex lens 12 which is also not coated. The convex surface of the concave-convex lens 12 is coated with a 473nm anti-reflection film, which is the final output surface of the laser. The 473nm high-brightness blue laser beam output from the convex surface of the concave-convex lens 12 has a diameter of 10mm, a divergence angle of less than 0.05mrad, and an output wavefront of one-third of the wavelength. When the output power of the pump source 03 is 5.4W, the output power of the 473nm blue laser is 1.02W.

[0023] The three-point temperature compensation temperature control part is composed of the pump source 03 working temperature compensation control component, the dielectric crystal 07 working temperature compensation control component, the frequency doubling crystal 08 working temperature control component and the temperature acquisition and control system. The pump source 03 working temperature compensation control component is composed of the pump source heat sink 13, the pump source working temperature sensor 14, the pump source temperature control semiconductor refrigerator 15, the shell bottom plate 22 and the pump source temperature control group CON3 of the control system 23. When the laser is working, according to the characteristic that the output wavelength of the pump source changes by 0.3nm for every 1℃ change in the working temperature, the pump source 03 temperature control group CON3 of the control system 23 compensates and controls the pump source 03 to work constantly at the temperature point where its output wavelength is 807nm. The dielectric crystal 07 working temperature compensation control component is composed of the dielectric crystal heat sink 16, the dielectric crystal working temperature sensor 17, the dielectric crystal temperature control semiconductor refrigerator 18, the shell bottom plate 22 and the temperature control group CON2 of the dielectric crystal 07 in the control system 23. When the laser is working and the pump source 03 outputs a pump power of 5.4W, the temperature control group CON2 of the dielectric crystal 07 in the control system 23 is used to compensate and control the dielectric crystal 07 to work constantly at 19.3°C. The equivalent thermal lens generated by the dielectric crystal 07 matches the plano-concave rear cavity mirror 06 to eliminate the aberration of the oscillation light in the cavity. The frequency doubling crystal 08 working temperature compensation control component is composed of a frequency doubling crystal heat sink 19, a frequency doubling crystal working temperature sensor 20, a frequency doubling crystal temperature control semiconductor refrigerator 21, a housing bottom plate 22 and a temperature control group CON1 of the frequency doubling crystal 08 in the control system 23. When the laser is working, the temperature control group CON1 of the frequency doubling crystal 08 in the control system 23 is used to compensate and control the frequency doubling crystal 08 to work constantly at 30.5°C, so that the frequency doubling efficiency of the frequency doubling crystal 08 is the highest. By compensating and controlling the working temperatures of the three devices of the pump source 03, the dielectric crystal 07 and the frequency doubling crystal 08 respectively, the laser output power stability is better than 1%, and the light-light conversion efficiency from the pump source to the output light is greater than 18%.

Claims

1. A three-point temperature compensated 473nm blue continuous laser, characterized in that It comprises a pump source semiconductor laser (03), and along the laser output direction of the semiconductor laser (03) are a cylindrical fast axis compression microlens (04), an aspheric coupling focusing lens (05), a plano-concave rear cavity mirror (06), a dielectric crystal (07), a frequency doubling crystal (08), a planar output cavity mirror (09), a double concave shaping beam expanding lens (10) and a double-cemented collimating output lens (11 / 12): The positive electrode (032) of the semiconductor laser (03) is fixed to one end of the upper surface of the first heat sink (13); the other end of the upper surface of the first heat sink (13) is fixed with a pump source negative electrode connecting plate (01) through an insulating material (02); the negative electrode (033) of the pump source is connected to the negative electrode connecting plate (01) through a negative electrode lead (031); the lower surface of the first heat sink (13) is in contact with the temperature control surface of the first semiconductor refrigerator (15); the other surface of the first semiconductor refrigerator (15) is in contact with the heat dissipation shell bottom plate (22) of the laser; the first heat sink (13), the first temperature sensor (14), the first semiconductor refrigerator (15), the shell bottom plate (22) and the third temperature acquisition and control system (CON3) constitute a pump source working temperature compensation control component, which acquires and controls the working temperature of the semiconductor laser (03) so that its output wavelength works at the maximum absorption peak of the dielectric crystal; The dielectric crystal (07) is installed in the through hole in the middle of the second heat sink (16), the inner wall of the heat sink through hole is in contact with the four sides of the dielectric crystal (07), the bottom surface of the second heat sink (16) is in contact with the temperature control surface of the second semiconductor refrigerator (18), the other side of the second semiconductor refrigerator (18) is in contact with the bottom plate (22) of the whole machine housing, and the second temperature sensor (17) is installed inside the second heat sink (16); the second heat sink (16), the second temperature sensor (17), the second semiconductor refrigerator (18), the bottom plate (22) of the housing and the second temperature acquisition and control system (CON2) constitute a dielectric crystal working temperature compensation control component, which collects and controls the working temperature of the dielectric crystal (07) so that it can stably work at a selected temperature point; The frequency doubling crystal (08) is installed in the middle through hole of the third heat sink (19), the inner wall of the heat sink is in contact with the four sides of the frequency doubling crystal, the bottom surface of the third heat sink (19) is in contact with the temperature control surface of the third semiconductor refrigerator (21), the other side of the third semiconductor refrigerator (21) is in contact with the bottom plate (22) of the whole machine shell, and the third temperature sensor (20) is installed inside the third heat sink (19); the third heat sink (19), the third temperature sensor (20), the third semiconductor refrigerator (21), the bottom plate (22) of the shell and the third temperature acquisition and control system (CON1) constitute the working temperature compensation control component of the frequency doubling crystal (08), collect and adjust the working temperature of the frequency doubling crystal (08), so that its frequency doubling efficiency is the highest and it works stably at the matching temperature point; The light emitting surface of the semiconductor laser (03) is glued to the cylindrical fast axis compression microlens (04); The concave curvature of the plano-concave rear cavity mirror (06) matches the focal length of the thermal effect lens of the dielectric crystal (07), and together they eliminate the aberration of the oscillating fundamental frequency light, so that the beam waist of the oscillating fundamental frequency light is located on the inner surface of the planar output cavity mirror (09); The semiconductor laser (03) outputs pump light to pump the dielectric crystal (07), which is excited to produce a quasi-three-level fundamental frequency 946nm laser, which is inserted into the cavity through a frequency doubling crystal (08) to form a 473nm frequency-doubled high-brightness blue laser, which is output through the planar output cavity mirror (09) and passes through the double concave shaping beam expansion lens (10) and the double-glued collimating output lens (11 / 12) to form an output light with a wavefront reaching one-third of the wavelength.

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