JP2008016833A - Joining method of opttical components, optical component integrated structure, and laser oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for integrating an optical component that is not, which is not degraded by high-output laser beams and high temperature, and also to provide a laser oscillator made of integrated multiple optical components. <P>SOLUTION: The joining method of optical components comprises steps of: forming one dielectric thin film on the junction surface of one optical component 8; forming the other dielectric thin film on the junction surface of the other optical component 9; and joining the one dielectric thin film to the other dielectric thin film without dispersion of light. Predetermined optical wavelength properties are obtained by joining the other dielectric thin film to the one dielectric thin film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for joining optical members and a laser oscillation device constituted by the optical members.

  In recent years, there has been a demand for miniaturization and high output of laser oscillation devices. There is a solid-state laser oscillation device as a compact and simple laser oscillation device that oscillates a laser, and the solid-state laser oscillation device is composed of a plurality of optical members (solid-state laser medium). Further, as the optical member is downsized, the optical members are integrated by bonding.

  Conventionally, a plurality of optical members are integrated by joining the optical members with an adhesive. In addition, the laser oscillator has been increased in output while being downsized, and along with the increase in output, a high-energy laser beam is incident on the optical member, and the optical member is also heated.

  In general, the adhesive is more likely to deteriorate with respect to a laser beam and with respect to a high temperature than an optical member. In a low-power laser oscillation device, even if an adhesive is used to integrate the optical members, the energy of the laser beam is low and the temperature of the optical members is low, so the deterioration of the adhesive is not a problem. However, in the high-power laser oscillation device, there has been a problem of shortening the life of the optical member due to deterioration of the adhesive.

  An example of a laser oscillation apparatus that uses an optical member and generates a high-power laser beam is disclosed in Patent Document 1.

JP 2004-111542 A

  In view of such circumstances, the present invention provides an optical member integration method that does not deteriorate even with a high-power laser beam or a high temperature, and a laser oscillation device in which a plurality of optical members are integrated.

  The present invention includes a step of forming one dielectric thin film on the bonding surface of one optical member, a step of forming the other dielectric thin film on the bonding surface of the other optical member, the one dielectric thin film, An optical member capable of obtaining a predetermined optical wavelength characteristic by bonding the other dielectric thin film and the one dielectric thin film to each other. In addition, the dielectric film formed by joining the one dielectric thin film and the other dielectric thin film relates to the joining method of the optical member which is a multilayer film, and does not scatter the light. The bonding is an optical contact, the bonding without light scattering is diffusion bonding, and the bonding without light scattering relates to a method for bonding optical members that is ultrasonic bonding.

  The present invention also includes one dielectric thin film formed on the joint surface of one optical member and the other dielectric thin film formed on the joint surface of the other optical member, wherein the two optical members are connected to the one optical member. The dielectric thin film and the other dielectric thin film are joined together by a joint that does not scatter light, and the one dielectric thin film and the other dielectric thin film are joined to each other, thereby having a required optical wavelength characteristic. The present invention relates to an optical member integrated structure in which a dielectric film is formed, and the dielectric film is composed of a multilayer dielectric thin film, and the one dielectric thin film and the other dielectric thin film are joined by a light scattering-free joint. The present invention relates to an optical member integrated structure in which one of the multilayer films is formed by bonding, and the dielectric film is composed of a multilayer dielectric thin film, the one dielectric thin film and the other dielectric Bonding the thin film by bonding without light scattering, The present invention relates to an optical member integrated structure in which two adjacent layers of a multilayer film are formed by an electric thin film and the other dielectric thin film, and the one optical member emits basic light by excitation light from a light source. The other optical member is a wavelength conversion crystal that converts the wavelength of the fundamental light, and the dielectric thin film is an optical member integrated structure that transmits the fundamental light and reflects the wavelength-converted light. Bonding without scattering is an optical contact, bonding without light scattering is diffusion bonding, and bonding without light scattering relates to an optical member integrated structure that is ultrasonic bonding. is there.

  Furthermore, the present invention provides a laser crystal that emits fundamental light by excitation light from a light source, a wavelength conversion crystal that is integrated with the laser crystal via a third dielectric film and converts the wavelength of the fundamental light, and the laser. A first dielectric film formed on an incident surface of the crystal, and a second dielectric film formed on an emission surface of the wavelength conversion crystal, wherein the first dielectric film transmits excitation light. The third dielectric film is formed by joining the laser crystal side film and the wavelength conversion crystal side film by a joint that does not scatter light, and the third dielectric film is a basic film. The present invention relates to a laser oscillation device configured to transmit light, reflect wavelength-converted light, and the second dielectric film reflects basic light and transmits wavelength-converted light. The optical contact and the non-scattering junction are diffusion junctions, and Scattered without joining the serial light is according to a laser oscillation apparatus is an ultrasonic bonding.

  According to the present invention, the step of forming one dielectric thin film on the bonding surface of one optical member, the step of forming the other dielectric thin film on the bonding surface of the other optical member, and the one dielectric thin film And joining the other dielectric thin film without scattering of light, and joining the other dielectric thin film and the one dielectric thin film provides a predetermined optical wavelength characteristic. Therefore, it is possible to eliminate the adhesive for joining the optical members, and it is possible to prevent the shortening of the life due to the deterioration of the adhesive.

  According to the invention, there is provided one dielectric thin film formed on the joint surface of one optical member and the other dielectric thin film formed on the joint surface of the other optical member, The one dielectric thin film and the other dielectric thin film are joined by a joint that does not scatter light, and the one dielectric thin film and the other dielectric thin film are joined together to obtain a required optical wavelength characteristic. Therefore, the adhesive can be eliminated for joining the optical members, and the shortening of the life due to the deterioration of the adhesive can be prevented.

  According to the present invention, the dielectric film is composed of a multilayer dielectric thin film, and the one dielectric thin film and the other dielectric thin film are joined by a joint that does not scatter light. Since one of the inner layers is formed, the optical contact is performed between films of the same quality, and a high-quality bonded state is obtained.

  Furthermore, according to the present invention, a laser crystal that emits basic light by excitation light from a light source, a wavelength conversion crystal that is integrated with the laser crystal through a third dielectric film and converts the wavelength of the basic light, A first dielectric film formed on an incident surface of the laser crystal; and a second dielectric film formed on an emission surface of the wavelength conversion crystal, wherein the first dielectric film is an excitation light. The third dielectric film is formed by joining the laser crystal side film and the wavelength conversion crystal side film by a joint that does not scatter light, and the third dielectric film. Transmits the fundamental light, reflects the wavelength-converted light, and the second dielectric film is configured to reflect the fundamental light and transmit the wavelength-converted light. Adhesive deterioration due to high-power laser beam can be prevented, and stable laser beam output can be obtained. Both exhibit excellent effects such as attained an extended service life to the laser oscillator.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  First, referring to FIG. 1, an outline of a laser oscillation apparatus in which the present invention is implemented will be described.

  FIG. 1 shows an example of a laser oscillation apparatus 1 which is a one-wavelength oscillation type LD-pumped solid-state laser apparatus.

  In FIG. 1, 2 is a light emission part, 3 is an optical resonance part. The light emitting unit 2 includes an LD light emitter 4 and a condenser lens 5, and the optical resonator 3 further includes a first optical crystal (laser crystal 8) and a second optical crystal on which a first dielectric reflection film 7 is formed. A crystal (nonlinear optical crystal (NLO) (second-harmonic wavelength conversion crystal 9)), a concave mirror 12 on which a second dielectric reflection film 11 is formed, and pumps a laser beam in the optical resonator 3 Then, it is output after resonance and amplification. The laser crystal 8 is Nd: YVO4 or the like, and the second harmonic wavelength conversion crystal 9 is KTP (KTiOPO4 potassium titanyl phosphate) or the like.

  The light emitting unit 2 is for emitting a laser beam having a wavelength of 809 nm, for example, and the LD light emitter 4 which is a semiconductor laser is used. Further, the LD light emitter 4 has a function as a pump light generator for generating the excitation light 17. The light emitting unit 2 is not limited to a semiconductor laser, and any light source means can be employed as long as it can generate a laser beam.

  The laser crystal 8 is for generating a fundamental wave 18 having a predetermined wavelength from the excitation light 17. For the laser crystal 8, Nd: YVO4 having an oscillation line of 1064 nm is used. In addition, YAG (yttrium aluminum garnet) doped with Nd3 + ions or the like is adopted, and YAG has oscillation lines such as 946 nm, 1064 nm, and 1319 nm. Further, Ti (Sapphire) having an oscillation line of 700 to 900 nm can be used.

  The first dielectric reflection film 7 is formed on the end surface (incident surface) of the laser crystal 8 on the LD light emitter 4 side, and the third dielectric reflection film 13 is formed on the emission surface of the laser crystal 8. And the second dielectric reflecting film 11 is formed on the concave mirror 12.

  The first dielectric reflecting film 7 is highly transmissive to the laser beam (excitation light 17) from the LD light emitter 4, and is high to the oscillation wavelength (fundamental wave 18) of the laser crystal 8. It is a reflection.

  The third dielectric reflection film 13 is highly transmissive with respect to the fundamental wave 18, and the second harmonic 19 converted by the second harmonic wavelength conversion crystal 9 (SHG: SECOND HARMONIC GENERATION). Is highly reflective.

  The concave mirror 12 is configured to face the laser crystal 8, and the laser crystal 8 side of the concave mirror 12 is processed into the shape of a concave spherical mirror having an appropriate radius, and the second dielectric A body reflection film 11 is formed. The second dielectric reflecting film 11 is highly reflective to the fundamental wave 18 and highly transmissive to the second harmonic 19.

  The dielectric material constituting the reflective film includes alternating multilayers such as TiO2 (n = 2.3 to 2.55) as a high refractive material and MgF2 (n = 1.32 to 1.39) as a low refractive material. It is a film.

  The linearly polarized excitation light 17 is emitted from the light emitting section 2, and the excitation light 17 passes through the first dielectric reflection film 7 and enters the laser crystal 8, whereby the fundamental wave 18 is oscillated. The fundamental wave 18 is pumped between the first dielectric reflection film 7 and the second dielectric reflection film 11, and further, the fundamental wave 18 is incident on the second harmonic wave wavelength conversion crystal 9. A second harmonic 19 is generated.

  The second harmonic 19 is transmitted through the second dielectric reflective film 11 and emitted, and is reflected by the third dielectric reflective film 13 and transmitted through the second dielectric reflective film 11. And injected. Although the polarization state is changed by transmitting a laser beam through the laser crystal 8, the second harmonic 19 reflected by the third dielectric reflection film 13 does not pass through the laser crystal 8. The polarization state is maintained, and the second harmonic (laser beam) of linearly polarized light is emitted from the optical resonator 3.

  As described above, the first dielectric reflection film 7 of the laser crystal 8 and the second dielectric reflection film 11 of the concave mirror 12 are combined, and the laser beam from the LD emitter 4 is collected. When the laser crystal 8 is pumped through the optical lens 5, light is transmitted between the first dielectric reflection film 7 of the laser crystal 8 and the second dielectric reflection film 11 of the concave mirror 12. Since it can reciprocate and confine the light for a long time, it can be amplified by resonating the light.

  The wavelength conversion crystal for second-order harmonics is formed in the optical resonance section 3 constituted by the first dielectric reflection film 7 of the laser crystal 8 and the second dielectric reflection film 11 of the concave mirror 12. 9 is inserted. When strong coherent light such as a laser beam is incident on the wavelength conversion crystal 9 for second harmonic, a second harmonic that doubles the optical frequency is generated. The generation of the second harmonic is called SECOND HARMONIC GENERATION. Therefore, when a laser beam is incident on the laser crystal 8 and a fundamental wave 18 having a wavelength of 1064 nm is oscillated, a laser beam having a wavelength of 532 nm (green laser beam) is emitted from the laser oscillation device 1.

  FIG. 2 shows an optical resonator 3 in which the laser crystal 8 that is an optical member and the wavelength conversion crystal 9 for second harmonic are integrated. In FIG. 2 and FIG. 3, the same components as those shown in FIG.

  The laser crystal 8 and the second harmonic wave wavelength conversion crystal 9 are integrated with each other through a third dielectric reflection film 13 by a bonding method without light scattering. Note that bonding without light scattering includes optical contact (bonding at an optical interface without light scattering), diffusion bonding, ultrasonic bonding, and the like.

  The first dielectric reflection film 7 is formed on the incident surface of the laser crystal 8, and the second dielectric reflection film 11 is formed on the emission surface of the second harmonic wavelength conversion crystal 9. Has been. The concave mirror 12 is omitted because the second dielectric reflection film 11 is formed on the emission surface of the second harmonic wavelength conversion crystal 9.

  The excitation light 17 incident on the laser crystal 8 is pumped between the first dielectric reflection film 7 and the second dielectric reflection film 11, and further 2 with the second harmonic wavelength conversion crystal 9. Oscillated by the second harmonic 19, the second harmonic 19 passes through the second dielectric reflection film 11 and is emitted.

  Next, the integration of the laser crystal 8 and the second harmonic wavelength conversion crystal 9 will be described with reference to FIG.

  As for the dielectric films such as the first dielectric reflection film 7, the third dielectric reflection film 13, and the second dielectric reflection film 11, a thin film of a required material obtains a required optical wavelength characteristic. The film is formed in multiple layers, and the required optical performance is exhibited.

  For example, the first dielectric reflection film 7 is formed by alternately forming several tens of layers of Ta2 O5 and SiO2. In FIG. 3, the first dielectric reflection film 7, the third dielectric reflection film 13, and the second dielectric reflection film 11 are shown in four layers for convenience.

  The third dielectric reflecting film 13 is assumed to be composed of thin films 13a, 13b, 13c, 13d, and any one of the thin films 13a, 13b, 13c, 13d has a boundary surface, and the laser crystal 8 and the second harmonic wavelength conversion crystal 9 are joined by optical contact at the interface.

  For example, if the boundary 14 is in the middle of the thin film 13b, the thin film 13a and a thin film 13b 'which is a part of the thin film 13b are formed on the emission surface of the laser crystal 8, and the second harmonic wave is used. On the incident surface of the wavelength conversion crystal 9, a thin film 13b '' and the thin films 13c and 13d, which are the remaining part of the thin film 13b, are formed.

  The exit surface of the laser crystal 8 and the incident surface of the wavelength conversion crystal 9 for second harmonic wave are finished to have a flatness and a planar roughness capable of optical contact, and the thin film 13b ′ and the thin film 13b ″ are formed. Even after film formation, the flatness and flatness capable of optical contact are maintained.

  The bonding surface of the thin film 13b ′ and the bonding surface of the thin film 13b ″ are cleaned, and both the thin films 13b ′ and 13b ″ are brought into close contact with each other to press the laser crystal 8 and the second harmonic wave wavelength conversion crystal 9 To do.

  The laser crystal 8 and the second-harmonic wavelength conversion crystal 9 are joined by optical contact between the thin films 13b ′ and 13b ″. In the joined state, the thin film 13b is constituted by both thin films 13b 'and 13b' '. The thin film 13b 'and the thin film 13b "are joined by the same material and have good affinity, and no shear is caused by the difference in thermal expansion between the thin films 13b' and 13b".

  Thus, the thin films 13b ′ and 13b ″ after bonding function as the thin film 13b, and the thin films 13a, 13b, 13c, and 13d function as the third dielectric reflecting film 13.

  In the above-described embodiment, the bonding is performed between the single thin films. However, bonding by optical contact may be performed at the boundary between the thin films. For example, the thin film 13b and the thin film 13c may be joined.

  As a bonding method that does not scatter light, the bonding surface is pressed in a heated state. Alternatively, a required liquid such as pure water is interposed between the thin films 13b 'and 13b' ', and the thin films 13b' and 13b '' are pressed and further heated to remove the liquid and obtain an optical contact. Etc. Further, the bonding method that does not scatter light may be diffusion bonding or ultrasonic bonding.

  As a cleaning method for cleaning the bonding surface of the thin film 13b ′ and the bonding surface of the thin film 13b ″, and a cleaning method for activating the thin film 13b ′, cleaning using HF or OH group, ultrasonic Examples include cleaning using vibration, cleaning using ion sputtering, and cleaning using plasma.

It is a schematic block diagram of the laser oscillation apparatus with which this invention is implemented. It is explanatory drawing of the optical resonance part which integrated two optical members. It is a schematic diagram which shows the dielectric material film formed in the optical member. FIG. 4 is a partially enlarged view of FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser oscillation apparatus 2 Light emission part 3 Optical resonance part 4 LD light emitter 7 1st dielectric reflection film 8 Laser crystal 9 Wavelength conversion crystal for 2nd harmonics 11 2nd dielectric reflection film 13 3rd dielectric reflection Film 17 Excitation light 18 Fundamental wave 19 Second harmonic

Claims (10)

  Forming one dielectric thin film on the bonding surface of one optical member, forming the other dielectric thin film on the bonding surface of the other optical member, the one dielectric thin film and the other dielectric And a step of bonding the thin film to each other without scattering of light, and a predetermined optical wavelength characteristic is obtained by bonding the other dielectric thin film and the one dielectric thin film. Member joining method.   2. The method for joining optical members according to claim 1, wherein the dielectric film formed by joining the one dielectric thin film and the other dielectric thin film is a multilayer film.   One dielectric thin film formed on the bonding surface of one optical member, and the other dielectric thin film formed on the bonding surface of the other optical member, the two optical members being the one dielectric thin film The other dielectric thin film is joined by a joint that does not scatter light, and the one dielectric thin film and the other dielectric thin film are joined to form a dielectric film having a required optical wavelength characteristic. An optical member integrated structure characterized by that.   The dielectric film is composed of a multilayer dielectric thin film, and the one dielectric thin film and the other dielectric thin film are joined together by joining without scattering of light, thereby forming one layer of the multilayer film. The optical member integrated structure according to claim 3.   The dielectric film is composed of a multilayer dielectric thin film, and the one dielectric thin film and the other dielectric thin film are joined together by a non-scattering joint, and the one dielectric thin film and the other dielectric thin film are joined. 4. The optical member integrated structure according to claim 3, wherein two adjacent layers of the multilayer film are formed by the thin film.   The one optical member is a laser crystal that emits basic light by excitation light from a light source, the other optical member is a wavelength conversion crystal that converts the wavelength of the basic light, and the dielectric thin film transmits basic light. And the optical member integrated structure of Claim 3 which reflects wavelength conversion light.   Formed on the incident surface of the laser crystal, a laser crystal that emits basic light by excitation light from a light source, a wavelength conversion crystal that is integrated with the laser crystal via a third dielectric film and converts the wavelength of the basic light And a second dielectric film formed on the exit surface of the wavelength conversion crystal, wherein the first dielectric film transmits excitation light and reflects basic light. The third dielectric film is formed by joining a laser crystal side film and a wavelength conversion crystal side film by a joint that does not scatter light, and the third dielectric film transmits fundamental light and has a wavelength of A laser oscillation device characterized in that the second dielectric film reflects the converted light, reflects the basic light, and transmits the wavelength-converted light.   8. The optical member joining method according to claim 1, or the optical member integrated structure according to any one of claims 3 to 5, or the laser oscillation device according to claim 7, wherein the joining without scattering of light is an optical contact.   The optical member bonding method according to claim 1, the optical member integrated structure according to claim 3, or the laser oscillation device according to claim 7, wherein the bonding without scattering of light is diffusion bonding.   The joining without light scattering is ultrasonic joining, the optical member joining method according to claim 1, the optical member integrated structure according to any one of claims 3 to 5, or the laser oscillation device according to claim 7.

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