WO2013153899A1

WO2013153899A1 - Laser device

Info

Publication number: WO2013153899A1
Application number: PCT/JP2013/057063
Authority: WO
Inventors: 高　新; 弘之大橋; 真大中村; 篠田　和憲
Original assignee: 浜松ホトニクス株式会社
Priority date: 2012-04-10
Filing date: 2013-03-13
Publication date: 2013-10-17
Also published as: JP2013219232A; JP6013007B2

Abstract

A laser device (10A) is provided with a microchip laser (12), a laser diode (14), a collimator lens (16), a folding mirror (18), a condensing lens (20), a base block (30A), a package (40) and a cooling mechanism (50). The folding mirror (18) collimates excitation light (L1), which has been output from the laser diode (14), in a slow axis direction, and reflects the excitation light (L1). The base block (30A) supports the microchip laser (12), the laser diode (14), the collimator lens (16), the folding mirror (18) and the condensing lens (20). A laser device that enables size reduction and packaging is achieved by means of this structure.

Description

Laser equipment

The present invention relates to a laser device.

As a laser light source, a laser medium that generates emission light by being supplied with excitation light and a saturable absorber that acts as a passive Q switch due to light absorption saturation and a saturable absorber that acts as a passive Q switch are used. The thing of the structure which has on an optical path is known. For example, Patent Document 1 describes a technique related to a solid-state laser device. The solid-state laser device described in this document includes a package, and an excitation light source and a microchip laser accommodated in the package.

Special table 2007-508682

In a laser light source including a laser medium and a saturable absorber, excitation light is supplied from the excitation light source to the laser medium. The excitation light is output from the laser light source, and then collimated in the fast axis direction and the slow axis direction, and then condensed toward the laser medium. Therefore, an optical system for collimating and condensing these is required.

On the other hand, depending on the application of the laser light source, miniaturization and packaging of the laser light source are required. Further, as the package, a package that can be hermetically sealed by a hermetic seal (for example, a 30 mm square small package) is desirable. However, as described above, a laser light source including a laser medium and a saturable absorber requires an optical system for collimation and condensing in addition to the laser medium and the saturable absorber. With the conventional configuration as described above, it is difficult to reduce the size and package.

The present invention has been made in view of such problems, and an object of the present invention is to provide a laser device that includes a laser medium, a saturable absorber, and an excitation light source, and can be reduced in size and packaged. And

In order to solve the above-described problems, a laser device according to the present invention includes a laser medium that generates excitation light upon receiving excitation light, a saturable absorber that reduces light absorption due to saturation of light absorption, and transmits excitation light. A laser oscillation unit formed by integrating a first reflection unit, and a second reflection unit having a laser medium and a saturable absorber on the resonance optical path to resonate emitted light together with the first reflection unit An excitation light source that outputs excitation light, a collimator that collimates the excitation light output from the excitation light source in the fast axis direction, and collimates the excitation light that has passed through the collimation part in the slow axis direction and reflects the excitation light A third reflecting portion, a condensing portion for condensing the excitation light reflected by the third reflecting portion toward the laser medium of the laser oscillation portion, a laser oscillation portion, an excitation light source, a collimating portion, and a third reflection The excitation light source in three axial directions orthogonal to each other and supporting the condensing unit, and the laser oscillation unit in two axial directions orthogonal to the optical axis direction of the excitation light incident on the first reflecting unit and orthogonal to each other. A base member to be positioned, a laser oscillation unit, an excitation light source, a collimator unit, a third reflection unit, a condensing unit, and a base member are accommodated, and a light emission window through which laser light output from the laser oscillation unit passes is provided. A package and a cooling mechanism thermally coupled to the base member are provided.

In this laser apparatus, the excitation light output from the excitation light source is first collimated in the fast axis direction by a collimating portion (for example, a collimating lens). Next, the excitation light is collimated in the slow axis direction by a third reflecting portion (for example, a member having a light reflecting surface curved in the slow axis direction), and the optical path is changed by reflection. Subsequently, the excitation light is condensed toward the laser medium of the laser oscillation unit by a condensing unit (for example, a condensing lens). In the laser oscillation part, emitted light is generated in the laser medium by this excitation light, and the saturable absorber operates as a passive Q switch, whereby laser resonance is intermittent between the first reflection part and the second reflection part. Occurs and a pulse laser beam is generated. The laser light passes through the light emission window of the package and is output to the outside of the package.

The laser oscillation part of the laser device is formed by integrating a laser medium, a saturable absorber, a first reflection part, and a second reflection part. Such a laser oscillation unit can reduce the size of the laser resonator. Further, in the above laser device, the optical path of the excitation light is bent when the third reflecting portion reflects the excitation light, so that the laser device can be downsized compared to the case where the optical path of the excitation light is linear. Can do. Furthermore, in the above laser apparatus, the third reflecting portion performs both the reflection of the excitation light and the collimation in the slow axis direction, so that it is possible to further reduce the size by omitting optical components for the collimation in the slow axis direction. . As described above, according to the laser device, the size can be significantly reduced as compared with the conventional laser device. Therefore, the package can be a small package capable of hermetic sealing, for example.

In the above laser apparatus, the base member positions the excitation light source in three axial directions orthogonal to each other (for example, the vertical direction, the horizontal direction, and the depth direction), and the optical axis of the excitation light incident on the first reflecting portion. The laser oscillation unit is positioned in two axial directions (for example, a lateral direction and a depth direction) perpendicular to the direction and perpendicular to each other. Thereby, the excitation light source and the laser oscillation part in a small laser device can be positioned easily and accurately. In addition, about the laser oscillation part, the position in the optical axis direction of the excitation light which injects into a 1st reflection part is possible, and the relative position of the condensing point by a condensing part and a laser oscillation part can be match | combined. .

According to the present invention, it is possible to miniaturize and package a laser device including a laser medium, a saturable absorber, and an excitation light source.

FIG. 1 is a plan view schematically showing the configuration of the laser apparatus according to the first embodiment. FIG. 2 is an exploded perspective view showing a detailed configuration of the laser apparatus according to the first embodiment. FIG. 3 is an exploded perspective view of the laser apparatus shown in FIG. 2 viewed from different angles. 4 is an exploded perspective view in which the microchip laser, the collimating lens, the folding mirror, and the condenser lens of the laser apparatus shown in FIG. 2 are omitted. FIG. 5 is a perspective view of the laser apparatus according to the first embodiment. FIG. 6 is an exploded perspective view showing the configuration of the laser apparatus according to the second embodiment.

Hereinafter, embodiments of a laser apparatus according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)

FIG. 1 is a plan view schematically showing the configuration of a laser apparatus 10A according to the first embodiment of the present invention. As shown in FIG. 1, the laser device 10 A of the present embodiment includes a microchip laser 12, a laser diode 14, a collimating lens 16 as a collimating part, a folding mirror 18 as a third reflecting part, and a condensing light. And a condensing lens 20 as a unit. Further, the laser device 10A includes a base block 30A and a package 40.

The microchip laser 12 is a laser oscillation unit in the present embodiment, and is configured by integrating a laser medium 12a, a saturable absorber 12b, a first reflection unit 12c, and a second reflection unit 12d. Note that the outer shape of the microchip laser 12 is, for example, a cylindrical shape having a central axis along a predetermined axial direction (optical axis direction). The first reflecting portion 12c, the laser medium 12a, the saturable absorber 12b, and the first The two reflecting portions 12d are arranged in this order along the predetermined axial direction.

The laser medium 12a contains a photoactive substance, and the photoactive substance is excited when the excitation light L1 output from the laser diode 14 is supplied to generate emission light from the photoactive substance. The laser medium 12a is preferably a crystal such as Nd: YAG or Yb: YAG. The thickness of the laser medium 12a is, for example, 0.01 mm to 1.5 mm.

The saturable absorber 12b has a light absorptivity that decreases due to saturation of light absorption, and is used as a passive Q switch in a laser resonator. That is, the saturable absorber 12b has a high light absorption rate when the light intensity is low, and when the light intensity exceeds a certain value, the light absorption is saturated and the light absorption rate decreases rapidly. The saturable absorber 12b is preferably a crystal such as Cr: YAG.

The first reflecting portion 12c transmits the excitation light L1 and reflects the emitted light. The second reflecting part 12d transmits part of the emitted light and reflects the remaining part. The reflectance of the second reflecting portion 12d at the wavelength of the emitted light is, for example, about 90%. The first reflecting portion 12c and the second reflecting portion 12d are preferably dielectric multilayer films. The first reflecting portion 12c and the second reflecting portion 12d constitute a laser resonator that has the laser medium 12a and the saturable absorber 12b on the resonance optical path and resonates the emitted light.

The microchip laser 12 operates as follows. The emitted light generated in the laser medium 12a excited by the excitation light L1 reaches the saturable absorber 12b. When the power of the emitted light generated in the laser medium 12a is low, the saturable absorber 12b has a high light absorptance, and laser oscillation does not occur in the laser resonator. Eventually, when the power of the emitted light generated in the laser medium 12a increases and the light intensity in the saturable absorber 12b exceeds a certain value, the light absorption of the saturable absorber 12b is saturated and the light absorption rate is suddenly increased. Becomes smaller. When the light absorptance of the saturable absorber 12b decreases, the emitted light generated in the laser medium 12a can pass through the saturable absorber 12b, and between the first reflecting portion 12c and the second reflecting portion 12d. Reciprocating causes stimulated emission in the laser medium 12a. As a result, laser oscillation occurs in the laser resonator.

Further, as soon as such laser oscillation occurs, the power of the emitted light generated in the laser medium 12a decreases, the light absorption rate of the saturable absorber 12b increases, and the laser oscillation ends in the laser resonator. By repeating the above operation, the microchip laser 12 can output the pulsed laser beam L2.

The laser diode 14 is an excitation light source in the present embodiment, and outputs excitation light L1 for exciting the photoactive substance contained in the laser medium 12a. A drive unit 22 is electrically connected to the electrode of the laser diode 14. The laser diode 14 is driven by a drive current supplied from the drive unit 22 to output pulsed or continuous wave excitation light L1. For example, when the laser medium 12a is an Nd: YAG crystal, the wavelength of the excitation light L1 is 808 nm, and the wavelengths of the emitted light and the laser light L2 are 1064 nm.

The collimating lens 16 is a collimating part in this embodiment. The collimating lens 16 is disposed between the laser diode 14 and the folding mirror 18, and collimates (parallelizes) the excitation light L1 output from the laser diode 14 in the fast axis direction.

The folding mirror 18 is a third reflecting portion in the present embodiment. The folding mirror 18 has a reflecting surface 18 a that reflects the excitation light L 1 that has passed through the collimating lens 16. The angle θ between the optical axis of the excitation light L1 incident on the reflection surface 18a and the optical axis of the excitation light L1 after being reflected on the reflection surface 18a is an acute angle (that is, the incident angle is less than 45 °). The angle is preferably 45 ° or less (that is, the incident angle is 22.5 ° or less).

The folding mirror 18 further collimates the excitation light L1 in the slow axis direction. Specifically, the reflecting surface 18a is curved in a plane including the slow axis of the excitation light L1, and the curvature thereof is set so that the reflected excitation light L1 is collimated in the slow axis direction. The reflection surface 18a may be formed of a dielectric multilayer film having a high reflectance (for example, 90% or more) in the wavelength region of the excitation light L1.

Further, the reflection surface 18a of the folding mirror 18 may be provided with an antireflection film 18b that prevents reflection of laser light (return light) output from the first reflection portion 12c of the microchip laser 12. Thereby, damage to the laser diode 14 due to return light from the first reflecting portion 12c can be reduced. The antireflection film 18b may constitute a dichroic mirror that reflects light in the wavelength region of the excitation light L1 and passes light in the wavelength region of the return light.

The condensing lens 20 is a condensing part in this embodiment. The condenser lens 20 receives the excitation light L1 reflected by the folding mirror 18, converges the excitation light L1, and condenses it in the laser medium 12a. As a result, the energy density of the excitation light L1 is increased in the laser medium 12a, and the shortening of the pulse to be described later is facilitated.

The base block 30A is a base member in the present embodiment. The base block 30A is a member that supports the microchip laser 12, the laser diode 14, the collimator lens 16, the folding mirror 18, and the condenser lens 20.

Package 40 is a container that houses microchip laser 12, laser diode 14, collimator lens 16, folding mirror 18, condenser lens 20, and base block 30A. A light exit window 41 is provided on the side wall of the package 40, and the laser light L 2 output from the microchip laser 12 passes through the light exit window 41 and is output to the outside of the package 40.

In this laser apparatus 10A, the excitation light L1 output from the laser diode 14 is first collimated in the fast axis direction by the collimating lens 16. Since the divergence angle in the fast axis direction of the excitation light L1 is as large as 40 °, for example, collimation in the fast axis direction is first performed in this way. Next, the excitation light L1 is collimated in the slow axis direction by the folding mirror 18, and its optical path is changed by reflection. The divergence angle of the excitation light L1 in the slow axis direction is, for example, 7 °. Subsequently, the excitation light L 1 is condensed toward the laser medium 12 a of the microchip laser 12 by the condenser lens 20. In the microchip laser 12, emission light is generated in the laser medium 12a by the excitation light L1, and the saturable absorber 12b operates as a passive Q switch, so that the first reflection unit 12c and the second reflection unit 12d Laser resonance occurs intermittently between them, and the pulse laser beam L2 is generated. The laser light L2 passes through the light exit window 41 of the package 40 and is output to the outside of the package 40.

FIG. 2 is an exploded perspective view showing a detailed configuration of the laser apparatus 10A according to the present embodiment. FIG. 3 is an exploded perspective view of the laser device 10A shown in FIG. 2 viewed from different angles. 4 is an exploded perspective view in which the microchip laser 12, the collimating lens 16, the folding mirror 18, and the condensing lens 20 of the laser apparatus 10A shown in FIG. 2 are omitted. FIG. 5 is a perspective view of the laser device 10A. 2 to 5, illustration of the upper lid of the package is omitted for easy understanding.

As shown in FIGS. 2 to 5, the package 40 of the present embodiment is a substantially cubic container made of a metal with good heat dissipation (for example, Kovar). In one example, the package 40 is an HHL package. The package 40 includes a planar rectangular side wall 42 and a bottom plate 43 that closes the lower end of the side wall 42, and the side surface 42 is provided with the light emission window 41 described above. The light exit window 41 is made of a material that is transparent to the wavelength of the laser light output from the microchip laser 12. Inside the package 40, the base block 30A and the microchip laser 12, the laser diode 14, the collimating lens 16, the folding mirror 18, and the condenser lens 20 disposed on the base block 30A are accommodated. An upper lid (not shown) closes the upper end to provide an airtight seal.

Also, as shown in FIGS. 2 to 5, the base block 30A of the present embodiment is a member cut out from one material block (metal block), and is made of, for example, a metal with good heat dissipation. Made of oxygen-free copper. Since the base block 30A is accommodated in the substantially cubic package 40, the base block 30A has a planar shape such as a substantially rectangular shape.

A precision surface for supporting the microchip laser 12, the laser diode 14, the collimating lens 16, the folding mirror 18, and the condenser lens 20 is provided on the main surface of the base block 30A (the surface facing the upper lid of the package 40). Processing has been applied. Specifically, as shown in FIGS. 3 and 4, the main surface of the base block 30 A has a laser oscillation portion accommodation groove 31 that is a recess for accommodating and supporting the microchip laser 12, and a laser diode. 14 is a recess for accommodating and supporting the rectangular parallelepiped block 15 on which the collimator 14 is mounted, a collimator receiving groove 33 which is a recess for receiving and supporting the collimating lens 16, A condensing part accommodating groove 34 that is a concave part for accommodating and supporting the optical lens 20 and a pedestal 35 that is a convex part for supporting the folding mirror 18 are formed.

The laser oscillating portion receiving groove 31 has a semicircular cross section in accordance with the shape of the microchip laser 12 and extends in the direction along the optical axis direction of the excitation light L1 incident on the microchip laser 12. ing. The microchip laser 12 is accommodated in the laser oscillation portion accommodating groove 31 so that it is perpendicular to the optical axis direction of the excitation light L1 and perpendicular to each other (specifically, the optical axis direction of the excitation light L1). In the horizontal direction and the depth direction orthogonal to the vertical direction. The positioning accuracy is equivalent to the processing accuracy of the laser oscillation part accommodation groove 31, and is extremely high. The positioning of the microchip laser 12 in the optical axis direction of the excitation light L1 is adjusted during assembly so that the condensing point of the excitation light L1 by the condensing lens 20 is located in the laser medium 12a.

The excitation light source unit receiving groove 32 has a rectangular cross-sectional shape in accordance with the shape of the rectangular parallelepiped block 15. One side surface of the block 15 is positioned by contacting the side surface along the extending direction of the excitation light source housing groove 32. Further, another side surface perpendicular to the one side surface of the block 15 is positioned by contacting an end surface perpendicular to the extending direction of the excitation light source housing groove 32. The laser diode 14 mounted on the block 15 is positioned in two axial directions orthogonal to each other by these structures. Further, the positioning of the laser diode 14 in the direction orthogonal to these two axial directions (the depth direction of the excitation light source housing groove 32) depends on the thickness of the block 15 in this direction and the depth of the excitation light source housing groove 32. Done. That is, the positioning accuracy of the laser diode 14 is equivalent to the processing accuracy of the side surface, the end surface and the bottom surface of the excitation light source housing groove 32 and the processing accuracy of the thickness of the block 15 and is extremely high.

On the block 15, a member 24 formed by forming a metal film (pad) on an insulator is disposed. The metal film of the member 24 and the cathode electrode of the laser diode 14 are mutually connected by wire bonding. Electrically connected. Further, a rod-shaped electrode 23 extends from the metal film of the member 24 along the extending direction of the excitation light source housing groove 32. The laser diode 14 emits the excitation light L 1 in a direction intersecting with the extending direction of the excitation light source housing groove 32 (a direction orthogonal to the example).

The collimator receiving groove 33 has a rectangular cross-sectional shape in accordance with the cross-sectional shape of the collimating lens 16 perpendicular to the optical axis of the excitation light L1, and the optical axis of the excitation light L1 emitted from the laser diode 14 It extends in a direction along the direction. The angle formed between the extending direction of the collimator receiving groove 33 and the extending direction of the laser oscillation receiving groove 31 is preferably an acute angle, and more preferably 45 ° or less.

The collimating lens 16 is accommodated in the collimating portion accommodating groove 33, so that it is orthogonal to the optical axis direction of the excitation light L1 and orthogonal to each other (specifically, orthogonal to the optical axis direction of the excitation light L1). Horizontal direction and depth direction). The positioning of the collimating lens 16 in the optical axis direction of the excitation light L1 is adjusted during assembly so that the collimated excitation light L1 has a desired width.

The condensing part accommodation groove 34 extends in a direction along the optical axis direction of the excitation light L1 incident on the microchip laser 12 and is formed continuously with the laser oscillation part accommodation groove 31. The condensing lens 20 is accommodated in the condensing portion accommodating groove 34 so as to be coaxial with the microchip laser 12.

In the pedestal 35, the optical axis of the excitation light L1 emitted from the laser diode 14 and passing through the collimator lens 16 and the optical axis of the excitation light L1 passing through the condenser lens 20 and incident on the microchip laser 12 intersect each other. In other words, the central axis of the laser oscillation part accommodation groove 31 and the condensing part accommodation groove 34 and the central axis of the collimation part accommodation groove 33 are formed at a position where they intersect each other. The folding mirror 18 is mounted on the pedestal 35, and the recesses or projections of the folding mirror 18 are fitted into the projections or depressions provided on the pedestal 35, so that two axes perpendicular to the depth direction and perpendicular to each other are obtained. Positioned in the direction.

Note that the folding mirror 18 may be cut out from the material block as a unit with the base block 30A when the base block 30A is formed. That is, when the laser oscillation part accommodation groove 31, the excitation light source part accommodation groove 32, the collimator part accommodation groove 33, and the light collecting part accommodation groove 34 of the base block 30A are formed by cutting the material block, the folding mirror 18 is also combined. May be formed.

As shown in FIGS. 2 and 4, the laser device 10 A further includes a cooling mechanism 50. The cooling mechanism 50 is thermally coupled to the base block 30A and is disposed, for example, between the bottom plate 43 of the package 40 and the back surface of the base block 30A. The cooling mechanism 50 cools the microchip laser 12 and the laser diode 14 on the base block 30A by transferring heat from the base block 30A to the package 40. The cooling mechanism 50 is composed of, for example, an electronic cooling element (Peltier element), and operates by receiving a drive current from a temperature control circuit provided outside the package 40. Although the cooling mechanism 50 of the present embodiment is disposed between the package 40 and the back surface of the base block 30A, the cooling mechanism may be provided outside the package 40, for example, on the bottom surface of the bottom plate 43. In that case, the cooling mechanism 50 cools the microchip laser 12 and the laser diode 14 on the base block 30A by absorbing heat from the base block 30A via the package 40 and releasing the heat to the outside of the package 40. To do.

The laser device 10A further includes a temperature measuring unit 60. The temperature measurement unit 60 is an element that outputs an electrical signal corresponding to the temperature, and indirectly measures the temperatures of the microchip laser 12 and the laser diode 14 by measuring the temperature of the base block 30A. The electrical signal output from the temperature measurement unit 60 is sent to the above-described temperature control circuit and used for controlling the cooling mechanism 50. The temperature measurement unit 60 of the present embodiment is provided between the microchip laser 12 and the laser diode 14 on the base block 30A (in other words, between the laser oscillation unit accommodation groove 31 and the excitation light source unit accommodation groove 32). It has been.

The effect obtained by the laser device 10A having the above configuration will be described. The microchip laser 12 of the laser device 10A is formed by integrating a laser medium 12a, a saturable absorber 12b, a first reflecting portion 12c, and a second reflecting portion 12d. With such a microchip laser 12, the laser resonator can be reduced in size. Further, in the laser device 10A, since the optical path of the excitation light L1 is bent when the folding mirror 18 reflects the excitation light L1, the laser device 10A is compared with the case where the optical path of the excitation light L1 is linear. It can be downsized. Further, in the laser device 10A, the folding mirror 18 performs both the reflection of the excitation light L1 and the collimation in the slow axis direction, so that the optical path for collimation in the slow axis direction is omitted, and the excitation light path is shortened. Further downsizing can be achieved.

Thus, according to the laser device 10A, since the size can be significantly reduced as compared with the conventional laser device, the package 40 can be a small package capable of hermetic sealing, for example.

Further, in the laser apparatus 10A, the position of the laser diode 14 and the position of the microchip laser 12 can be brought close to each other by folding the excitation light path by the folding mirror 18. When both the microchip laser 12 and the laser diode 14 are cooled by one cooling mechanism 50, it is difficult to accurately control each temperature if these distances are separated from each other, but in this embodiment, the laser diode 14 Since the position and the position of the microchip laser 12 can be brought close to each other, each temperature can be controlled with high accuracy.

Further, in the laser device 10A, the base block 30A positions the laser diode 14 in three axial directions orthogonal to each other (for example, the vertical direction, the horizontal direction, and the depth direction), and the excitation light incident on the first reflecting portion 12c. The microchip laser 12 is positioned in two axial directions (for example, a lateral direction and a depth direction) orthogonal to the optical axis direction of L1 and orthogonal to each other. Thereby, positioning of the laser diode 14 and the microchip laser 12 in the small laser device 10A can be performed easily and accurately. Further, as in the present embodiment, by fixing the microchip laser 12 and the laser diode 14 on the metal base block 30A, heat generated from the microchip laser 12 and the laser diode 14 can be efficiently radiated. Can do.

In addition, in the conventional laser device, it is necessary to assemble all the structures such as electrode insulation, assembly of the temperature measuring unit (Peltier element), and hermetic sealing with an O-ring at the time of manufacturing the laser device. Become. On the other hand, according to the laser device 10A of the present embodiment, since the microchip laser 12, the laser diode 14, and the like can be sealed in a small package using the hermetic seal technology, the assembly is easy, and the process The number can be reduced.

Also, as described above, since each component can be hermetically sealed in a small package, each component can be confined in a nitrogen atmosphere. Therefore, deterioration of the laser diode 14 and the optical thin film can be suppressed, and the reliability of the laser device 10A can be improved.

Further, as in the present embodiment, the laser device 10A may include a temperature measurement unit 60 provided between the microchip laser 12 and the laser diode 14 on the base block 30A. In the laser apparatus 10 A of the present embodiment, the laser diode 14 and the microchip laser 12 are close to each other due to the folding of the excitation light path by the folding mirror 18, so that the temperature measuring unit is between the laser diode 14 and the microchip laser 12. By providing 60, even if there is only one temperature measuring unit 60, these temperatures can be measured with high accuracy, and temperature control by the cooling mechanism 50 can be performed more accurately. More preferably, the temperature measuring unit 60 may be arranged on a straight line connecting the microchip laser 12 and the laser diode 14.

Further, as in this embodiment, the angle θ formed by the optical axis of the excitation light L1 incident on the folding mirror 18 and the optical axis of the excitation light L1 reflected by the folding mirror 18 is an acute angle (that is, the incident angle is 45 °). Less). Thereby, the distance between the laser diode 14 and the microchip laser 12 can be shortened, and the laser device 10A can be further miniaturized. When the incident angle to the folding mirror 18 is greater than 45 °, it is desirable that the reflecting surface 18a be a parabolic surface instead of a cylindrical surface in order to obtain a sufficient collimating action. On the other hand, when the angle of incidence on the folding mirror 18 is smaller than 45 °, the slow axis of the excitation light L1 can be approximately collimated even if the reflecting surface 18a is a cylindrical surface. can do.

The smaller the incident angle of the excitation light L1 to the folding mirror 18, the more accurately the slow axis of the excitation light L1 can be collimated even if the reflection surface 18a is a cylindrical surface. Therefore, the angle of incidence on the folding mirror 18 is more preferably 22.5 ° or less (that is, the angle θ is 45 ° or less).

Further, as described above, the folding mirror 18 may be cut out integrally with the base block 30A from the material block when the base block 30A is formed. Thereby, the positional accuracy of the folding mirror 18 can be further improved, and the folding mirror 18 can be effectively cooled.

(Second embodiment)

FIG. 6 is an exploded perspective view showing a configuration of a laser apparatus 10B according to the second embodiment of the present invention. Also in FIG. 6, the illustration of the upper lid of the package is omitted as in FIGS.

The difference between the laser apparatus 10B according to the present embodiment and the laser apparatus 10A according to the first embodiment described above is the configuration of the base member. The laser apparatus 10B of the present embodiment includes a base block 30B instead of the base block 30A of the first embodiment. The base block 30 B is a base member in the present embodiment, and is divided into a first member 36 that supports the microchip laser 12 and a second member 37 that supports the laser diode 14. The first member 36 and the second member 37 are arranged with a space therebetween in the package 40. Specifically, the microchip laser 12, the condenser lens 20, and the folding mirror 18 are arranged on the first member 36, and the block 15 on which the laser diode 14 is mounted and the collimating lens 16 are on the second member 37. Has been placed.

Further, the laser device 10B of this embodiment includes a first cooling mechanism 51 and a second cooling mechanism 52 instead of the cooling mechanism 50 of the first embodiment. The first cooling mechanism 51 is disposed between the back surface of the first member 36 and the bottom plate 43 of the package 40, and performs heat transfer from the first member 36 to the package 40, whereby the first cooling mechanism 51 on the first member 36. The chip laser 12 is cooled. The second cooling mechanism 52 is disposed between the back surface of the second member 37 and the bottom plate 43 of the package 40 (see FIGS. 2 and 4), and transfers heat from the second member 37 to the package 40. By doing so, the laser diode 14 on the second member 37 is cooled. The first cooling mechanism 51 and the second cooling mechanism 52 are configured by, for example, an electronic cooling element (Peltier element), and operate by receiving a drive current supplied from a temperature control circuit provided outside the package 40.

Further, the laser device 10B includes a first temperature measurement unit 61 and a second temperature measurement unit 62 instead of the temperature measurement unit 60 of the first embodiment. The 1st temperature measurement part 61 and the 2nd temperature measurement part 62 are elements which output the electrical signal according to temperature. The first temperature measurement unit 61 is provided on the first member 36 and indirectly measures the temperature of the microchip laser 12 by measuring the temperature of the first member 36. The second temperature measurement unit 62 is provided on the second member 37 and indirectly measures the temperature of the laser diode 14 by measuring the temperature of the second member 37. The electrical signal output from the first temperature measurement unit 61 is sent to the temperature control circuit and used for controlling the first cooling mechanism 51. Similarly, the electrical signal output from the second temperature measurement unit 62 is sent to the temperature control circuit and used for controlling the second cooling mechanism 52.

In the present embodiment, since the base block 30B is divided into a first member 36 that supports the microchip laser 12 and a second member 37 that supports the laser diode 14, the microchip laser 12 and the laser diode 14 The thermal influence during the can be reduced. In addition, a first cooling mechanism 51 and a first temperature measurement unit 61 are provided for cooling the microchip laser 12, and a second cooling mechanism 52 and a second temperature measurement unit 62 are used for cooling the laser diode 14. Therefore, the temperatures of the microchip laser 12 and the laser diode 14 can be controlled more stably. This stabilizes the light intensity and wavelength of the excitation light L1 output from the laser diode 14, and enables oscillation in the longitudinal single mode.

The laser apparatus according to the present invention is not limited to the above-described embodiment, and various other modifications are possible. For example, in the above embodiment, the excitation light L1 is reflected only once before reaching the microchip laser 12 from the laser diode 14, and the optical path of the excitation light L1 is V-shaped. The shape of the optical path of the excitation light is not limited to this, and may be a shape that reflects a plurality of times, for example, by adding a reflecting portion.

In the above embodiment, a microchip laser is exemplified as the laser oscillation unit. However, the present invention is not limited to this as long as it includes a laser medium, a saturable absorber, a first reflection unit, and a second reflection unit. In the above embodiment, a laser diode is exemplified as an excitation light source, but the present invention is not limited to this as long as it can output excitation light. Moreover, although the collimating lens is illustrated as a collimating part in the said embodiment, if it can collimate excitation light to a fast axis direction, it will not be restricted to this.

In the laser device according to the above embodiment, the laser medium that receives the excitation light and generates the emission light, the saturable absorber that decreases the light absorption rate due to the saturation of the light absorption, the first reflection unit that transmits the excitation light, and the laser medium And a laser oscillation unit comprising a saturable absorber on the resonant optical path and a laser resonator that resonates the emitted light together with the first reflective unit, and a pump that outputs pump light A light source, a collimator that collimates the excitation light output from the excitation light source in the fast axis direction, a third reflection unit that collimates the excitation light that has passed through the collimator part in the slow axis direction, and reflects the excitation light; Supports the condensing unit that condenses the excitation light reflected by the reflection unit toward the laser medium of the laser oscillation unit, and the laser oscillation unit, excitation light source, collimator unit, third reflection unit, and condensing unit A base member for positioning the excitation light source in three axial directions orthogonal to each other, and positioning the laser oscillation unit in two axial directions orthogonal to the optical axis direction of the excitation light incident on the first reflecting unit and orthogonal to each other; A package having a light exit window for accommodating the excitation light source, the collimating unit, the third reflecting unit, the condensing unit, and the base member, and allowing the laser beam output from the laser oscillation unit to pass through, and the base member thermally And a coupled cooling mechanism.

The laser device may further include a temperature measurement unit provided between the laser oscillation unit and the excitation light source on the base member. In the laser device described above, the excitation light source and the laser oscillation unit are close to each other due to the folding of the excitation optical path by the third reflection unit, so that by providing a temperature measurement unit between the excitation light source and the laser oscillation unit, Temperature control by the cooling mechanism can be performed more accurately.

Further, the laser device may have a configuration in which the third reflection unit has an antireflection film that prevents reflection of laser light output from the first reflection unit of the laser oscillation unit. Thereby, damage to the excitation light source due to the laser light (return light) output from the first reflection unit can be reduced.

Further, the laser device may be configured such that the angle formed by the optical axis of the excitation light incident on the third reflection portion and the optical axis of the excitation light reflected by the third reflection portion is an acute angle. Thereby, the laser device can be further reduced in size. In this case, the angle is preferably 45 ° or less.

Further, the laser device may be configured such that the third reflecting portion is cut out from the material lump as a unit with the base member. Thereby, the positional accuracy of the third reflecting portion can be further increased, and the third reflecting portion can be effectively cooled.

Further, in the laser apparatus, the base member is divided into a first member that supports the laser oscillation unit and a second member that supports the excitation light source, and the first member and the second member are arranged with a space therebetween. A first cooling mechanism disposed as a cooling mechanism between the first member and the package; a second cooling mechanism disposed as a cooling mechanism between the second member and the package; It is good also as a structure provided with the 1st temperature measurement part provided on the member, and the 2nd temperature measurement part provided on the 2nd member. With such a configuration, the thermal influence between the laser oscillation unit and the excitation light source can be reduced, and these temperatures can be controlled more stably.

The present invention includes a laser medium, a saturable absorber, and an excitation light source, and can be used as a laser device that can be miniaturized and packaged.

DESCRIPTION OF

SYMBOLS

10A, 10B ... Laser apparatus, 12 ... Microchip laser, 12a ... Laser medium, 12b ... Saturable absorber, 12c ... First reflection part, 12d ... Second reflection part, 14 ... Laser diode, 15 ... Block, 16 ... Collimating lens, 18 ... Folding mirror, 20 ... Condensing lens, 22 ... Drive unit, 30A, 30B ... Base block, 31 ... Laser oscillation housing groove, 32 ... Excitation light source housing groove, 33 ... Collimation housing housing, 34 ... Condensing part accommodation groove, 35 ... pedestal, 36 ... first member, 37 ... second member, 40 ... package, 41 ... light exit window, 42 ... side wall, 43 ... bottom plate, 50, 51, 52 ... cooling mechanism, 60 ... temperature measurement unit, 61 ... first temperature measurement unit, 62 ... second temperature measurement unit, L1 ... excitation light, L2 ... laser beam.

Claims

A laser medium that generates excitation light upon receiving excitation light, a saturable absorber that reduces light absorption by saturation of light absorption, a first reflector that transmits the excitation light, and the laser medium and the saturable absorber. A laser oscillating unit formed by integrating a second reflecting unit that constitutes a laser resonator that resonates the emitted light with the first reflecting unit on the resonant optical path;
An excitation light source that outputs the excitation light;
A collimator that collimates the excitation light output from the excitation light source in the fast axis direction;
Collimating the excitation light that has passed through the collimating portion in the slow axis direction, and a third reflecting portion that reflects the excitation light;
A condensing unit that condenses the excitation light reflected by the third reflecting unit toward the laser medium of the laser oscillation unit;
The laser oscillation unit, the excitation light source, the collimator unit, the third reflection unit, and the light collection unit are supported, and the excitation light source is positioned in three orthogonal directions and incident on the first reflection unit. A base member for positioning the laser oscillation unit in two axial directions orthogonal to the optical axis direction of the excitation light and orthogonal to each other;
A light emission window for accommodating the laser oscillation unit, the excitation light source, the collimator unit, the third reflection unit, the condensing unit, and the base member, and allowing a laser beam output from the laser oscillation unit to pass therethrough; A package having
A laser apparatus comprising: a cooling mechanism thermally coupled to the base member.
The laser device according to claim 1, further comprising a temperature measurement unit provided between the laser oscillation unit and the excitation light source on the base member.
3. The laser device according to claim 1, wherein the third reflection unit includes an antireflection film that prevents reflection of laser light output from the first reflection unit of the laser oscillation unit.
The angle formed by the optical axis of the excitation light incident on the third reflection portion and the optical axis of the excitation light reflected by the third reflection portion is an acute angle. The laser device according to any one of the above.
The laser device according to claim 4, wherein the angle is 45 ° or less.
The laser device according to any one of claims 1 to 5, wherein the third reflecting portion is cut out from a mass of material as one piece with the base member.
The base member is divided into a first member that supports the laser oscillating unit and a second member that supports the excitation light source, and the first member and the second member are spaced apart from each other. And
A first cooling mechanism disposed between the first member and the package;
A second cooling mechanism disposed between the second member and the package;
A first temperature measuring unit provided on the first member;
The laser device according to claim 1, further comprising: a second temperature measurement unit provided on the second member.