JPH0511294A - Optical crystal and semiconductor laser pumped solid-state laser device using the same - Google Patents

Abstract

(57) [Abstract] [Purpose] The direction of the electric field vector of an ordinary ray or an extraordinary ray of an optical crystal can be determined from its outline, and mounting and adjustment are facilitated. [Arrangement] A rectangular parallelepiped optical crystal body 1 is provided by cutting a ridgeline cutting portion 14a provided by cutting a ridgeline where a laser light incident surface 12 and a side surface intersect, or by cutting a corner formed by an end face and two side surfaces. And the side 13 of the incident surface 12 is parallel to the direction (o direction) of the electric field vector of the ordinary ray and is 90 ° or 45 °.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical crystal body having a shape for indicating a polarization direction and a semiconductor laser pumped solid-state laser device using the same.

[0002]

2. Description of the Related Art In recent years, a semiconductor laser has come to be used as an excitation light source for a solid-state laser with the increase in output of the semiconductor laser. When a semiconductor laser is used as the pumping light source, the pumping wavelength can be adjusted to the absorption band of the solid-state laser, so the pumping efficiency is very good, and since there is no heat generation due to absorption of extra spectrum, heat dissipation is also easy. A compact and highly efficient solid-state laser device can be realized.
In particular, the method of exciting with a semiconductor laser light from the axial end face direction of the solid-state laser crystal body has good excitation efficiency because the coupling efficiency of the oscillation modes of the semiconductor laser light and the solid-state laser light is good, and is suitable for a small solid-state laser device. There is.

On the other hand, a nonlinear optical crystal such as a KTiOPO ₄ (KTP) crystal is used to convert infrared light emitted from a solid-state laser device into higher harmonics to obtain green or blue visible light laser light. Has been known from the past, and small green or blue lasers have come to be realized in combination with the above-mentioned semiconductor laser pumped solid-state laser device.

A conventional semiconductor laser pumped solid-state laser device will be described below. FIG. 6 is a block diagram of a conventional semiconductor laser pumped solid-state laser device. Nd: YVO ₄ microchip 1 that is a solid-state laser crystal, KTP crystal 2 that is a nonlinear optical crystal, and semiconductor laser chip 3 that is an excitation light source
And for monitoring the output of the semiconductor laser chip 3.
The PIN photodiode 4 and the PIN photodiode 4 are housed in a package 6 having a glass window 5. The Nd: YVO ₄ microchip 1 and the KTP crystal 2 are fixed by independent fixing frames 7. The resonator of the Nd: YVO ₄ laser is formed between the end face of the Nd: YVO ₄ microchip 1 on the excitation side and the end face of the KTP crystal 2 on the emission side. The semiconductor laser chip 3 is placed close to or in close contact with the end face of the Nd: YVO ₄ microchip 1, and the light emitted from the semiconductor laser chip 3 is sufficiently exposed to N before it spreads.
d: YVO ₄ Microchip 1 can be excited. From the excited Nd: YVO ₄ microchip 1, the wavelength
The laser light of 1.064 μm is generated, and the laser light is converted by the KTP crystal 2 into the green light of the second harmonic wavelength of 0.532 μm.

As a nonlinear optical crystal body for generating such a second harmonic, a columnar one is generally used. An example using a rectangular parallelepiped nonlinear optical crystal body as shown in FIG. (See Japanese Patent Laid-Open No. 3-15833).
The nonlinear optical crystal body shown in FIG. 7 has an incident surface 8 that is phase-matched at one end, an exit end surface 9 is formed at the other end, and an outer surface 10 is formed in a rectangular parallelepiped shape.

In general, if the semiconductor laser pumped solid-state laser device shown in FIG. 6 is arranged without considering the crystal axes of the Nd: YVO ₄ microchip 1 and the KTP crystal 2, efficient oscillation characteristics cannot be obtained. In order to excite efficiently, the polarization direction of the solid-state laser light generated from the Nd: YVO ₄ microchip 1 and the polarization direction of the semiconductor laser light that is the excitation light must be matched. When converting the solid-state laser light that is the fundamental wave into the second harmonic by the KTP crystal 2, the maximum conversion efficiency is obtained when the polarization direction of the fundamental wave and the ordinary ray direction of the KTP crystal 2 become 45 degrees. be able to. Thus, by arranging the solid-state laser crystal body and the nonlinear optical crystal body in consideration of the crystal axes, a solid-state laser device having good pumping efficiency and conversion efficiency can be realized.

[0007]

However, the optical crystal body having the above-mentioned conventional structure has a shape in which the direction of the electric field vector of the extraordinary ray or the ordinary ray cannot be specified regardless of whether the shape is a rectangular parallelepiped or a cylinder. Therefore, when performing optical adjustment of the solid-state laser device, the direction of the electric field vector of the ordinary ray or the extraordinary ray cannot be determined from its shape, so the direction must be measured by actually injecting the laser light. There was a problem that it was very inconvenient to handle such as when it did not happen.

The present invention solves the above-mentioned conventional problems, and an optical crystal that can be easily optically adjusted to maximize the pumping efficiency and the conversion efficiency, and a semiconductor laser pumping using the same. An object is to provide a solid-state laser device.

[0009]

In order to achieve this object, the optical crystal body of the present invention, when the shape is a rectangular parallelepiped, is a side where an end face where laser light enters or exits and a side face intersect,
The corner formed by a part of the side or end face and two side faces is cut off, and one side of the end face is parallel to the direction of the electric field vector of the ordinary ray, in a relation of 90 degrees or 45 degrees. If the shape is a cylinder, the end face has at least one side that is cut out by a straight line, and that side is parallel to the direction of the electric field vector of the ordinary ray and has a relationship of 90 degrees or 45 degrees. have.

The semiconductor laser pumped solid-state laser device of the present invention has a structure in which the optical crystal body having the above-mentioned structure is used as a solid-state laser crystal body or a nonlinear optical crystal body.

[0011]

With this configuration, the direction of the electric field vector of an ordinary ray or an extraordinary ray of a solid laser crystal body or a nonlinear optical crystal body can be determined from its shape, and a semiconductor laser pumped solid state laser device using such an optical crystal body. Then, its assembly and adjustment are extremely easy.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 show an optical crystal body in an embodiment of the present invention, and FIG. 5 shows a structure of a semiconductor laser pumped solid-state laser device. In these figures, o indicates the direction of the electric field vector of the ordinary ray (Ordinary ray) (hereinafter referred to as o direction), and e indicates the direction of the electric field vector of the extraordinary ray (Extra-Ordinary ray) (hereinafter referred to as e direction). ing. Generally, the o and e directions are orthogonal. The laser light is assumed to be incident perpendicularly on the incident surface of the optical crystal.

1 (a) and 1 (b) are perspective views of an optical crystal body according to a first embodiment of the present invention. FIG. 1 (a) shows an incident surface 12 after the optical crystal body 11 is cut out. Is a rectangular parallelepiped in which one ridgeline is cut out and a ridgeline cutout portion 14a is provided. In this case, the o-direction or the e-direction can be easily discriminated by matching the ridgeline excision portion 14a or the side 13 with the o-direction or the e-direction. Moreover, although the example in which one ridgeline cutting portion 14a is provided is described in FIG. 1A, two or more ridgeline cutting portions 14a may be provided. See also FIG.
(B) is a rectangular parallelepiped in which the corner formed by the incident surface 12 and the two side surfaces is cut off to provide a corner cutting portion 14b. If the incident surface 12 can be specified by the difference in the coating film or the like, the o direction or e The direction can be determined. See also FIG.
Although an example in which one corner excision portion 14b is cut off is described in (b), two or more corner excision portions 14b may be provided.

2 (a) and 2 (b) are perspective views of an optical crystal body according to a second embodiment of the present invention. FIG. 2 (a) shows an incident surface when the optical crystal body 11 is cut out. 12 sides 1
3 is a rectangular parallelepiped in which the ridge line is cut parallel to the o direction, and the ridge line is cut in parallel to the traveling direction of the laser light to provide the ridge line cutting portion 14c. In such an optical crystal body 11, if the incident surface 12 can be specified by the difference in the coating film, the o direction or the e direction can be determined. See also FIG.
FIG. 2B is a view similar to that of FIG. 2A, in which two adjacent ridge lines parallel to the traveling direction of the laser light are cut to remove the ridge line cutting portion 14.
It is a rectangular parallelepiped provided with c and 14d, and in this case, the o direction or the e direction can be easily discriminated by keeping the side 13 and the o direction sandwiched by the adjacent ridgeline cutting portions 14c and 14d parallel to each other.

1 or 2, the same effect can be obtained even if the direction o is rotated by 45 degrees or 90 degrees with respect to one side.

FIG. 3 is a perspective view of an optical crystal body according to a third embodiment of the present invention, in which a notch 15a is provided in a part of the circumference of the incident surface 12 of a cylinder, which is in the o direction. Shows an example in which is perpendicular to the side 13 formed by the cutout 15a.

4 (a) and 4 (b) are perspective views of an optical crystal body according to a fourth embodiment of the present invention, and FIG. 4 (a) shows the optical crystal body 11 having one flat surface 15b on its side surface. And a side 13 is provided on the circumference of the incident surface 12 by forming a plane 15b on the side surface after cutting out the cylinder. Further, FIG. 4B is an example in which two flat surfaces 15b and 15c are provided on the side surface of the cylinder. Each of these figures shows an example in which the o direction is perpendicular to the side 13.

Similar effects can be obtained even if the structure shown in FIG. 3 or 4 is rotated by 45 ° or 90 ° in the o direction.

FIG. 5 shows a semiconductor laser according to an embodiment of the present invention.
It is a block diagram of a laser pumped solid-state laser device. Figure 5 shows Nd: Y
VO_FourThe microchip 1 having the shape shown in FIG.
Of the KTP crystal 2 having the shape shown in FIG.
The semiconductor laser chip was used as the excitation light source.
I am using type 3. Nd: YVO_FourMicrochip 1 on the side
It is a cylinder provided with a plane 15b, and the o direction is on the plane 15b.
It is cut out to be vertical. KTP crystal 2
A ridgeline cutting portion 14c parallel to the traveling direction of the laser light is provided.
It is a rectangular parallelepiped, and the e direction is perpendicular to the surface of the ridgeline excision portion 14c.
It has been cut out to become. Semiconductor with such a configuration
Semiconductor laser light from laser 3 is Nd: YVO _FourMicro chip
Excitation of the laser light, but the plane of polarization of the semiconductor laser light at that time
Is Nd: YVO_FourMatched to the o direction of the microchip 1
It Therefore Nd: YVO_FourEmitted from the microchip 1
The direction of the electric field vector of the solid-state laser light is o in the KTP crystal 2.
It will intersect the direction at 45 degrees. At this time, the conversion efficiency is the highest.
The electric field of the second harmonic emitted from the KTP crystal 2 becomes large.
The vector of is parallel to the o direction of KTP crystal 2.
There is.

A shape for discriminating the o-direction or the e-direction of the optical crystal is conceivable other than the above-mentioned embodiment.
A complicated shape increases the number of processing steps and is not practical.
The embodiment shown in FIGS. 1 to 4 can be processed relatively easily.

Further, a solid-state laser crystal body having a high pumping efficiency,
The thickness of the above-mentioned optical crystal body is reduced when a nonlinear optical crystal body with high conversion efficiency into the second harmonic or an efficient self-harmonic solid-state laser crystal body having the characteristics of both of them is used. However, in that case, the prism can be replaced by a square plate, and the cylinder can be replaced by a disc.

The ridgeline cutting portions 14c and 14d shown in FIGS. 2A and 2B, and the plane 15 shown in FIGS. 4A and 4B.
b and 15c are not only effective as marks indicating the polarization direction, but also when the Nd: YVO ₄ microchip 1 or KTP crystal 2 having such a shape is fitted into the fixing frame 7 shown in FIG. There is a gap between the inner wall of 7 and
By applying an adhesive agent to the gap and adhering the fixed frame 7 to the Nd: YVO ₄ microchip 1 and the KTP crystal 2, a structure free from distortion can be obtained. Also, in the bonding method in which the adhesive is applied to a place other than the gap, this gap can be used as an escape route for the adhesive, and Nd: YVO ₄ microchip 1 or K
Does not stain the end face of TP crystal 2.

[0023]

As described above, according to the present invention, the shape of an optical crystal such as a solid-state laser crystal or a nonlinear optical crystal can be defined to easily determine the direction of the electric field vector of an ordinary ray or an extraordinary ray. As a result, it is possible to realize an excellent optical crystal that can be easily handled when assembling and adjusting a semiconductor laser pumped solid-state laser device and a semiconductor laser-pumped solid-state laser device using the same. is there.

[Brief description of drawings]

1A and 1B are perspective views of an optical crystal body according to a first embodiment of the present invention.

2A and 2B are perspective views of an optical crystal body according to a second embodiment of the present invention.

FIG. 3 is a perspective view of an optical crystal body according to a third embodiment of the present invention.

4A and 4B are perspective views of an optical crystal body in a fourth embodiment of the present invention.

FIG. 5 is a configuration diagram of a semiconductor laser pumped solid-state laser device according to an embodiment of the present invention.

FIG. 6 is a block diagram of a conventional semiconductor laser pumped solid-state laser device.

FIG. 7 is a perspective view of a conventional nonlinear optical crystal body.

[Explanation of symbols]

11 Optical crystal 12 Incident surface (end surface) 13 sides 14a Ridge cutting part 14b Corner excision part oo direction (direction of electric field vector of ordinary ray) ee direction (direction of electric field vector of extraordinary ray)

Claims (5)

[Claims] 1. A cuboid having a substantially rectangular parallelepiped shape, a ridgeline at which an end face of the rectangular parallelepiped where laser light enters or exits intersects a side face, a part of the ridge line, or an angle formed by the end face and two side faces. Is cut off, and one side of the end face is parallel to the direction of the electric field vector of the ordinary ray and has a relationship of 90 degrees or 45 degrees. 2. The optical crystal body according to claim 1, wherein at least one of the ridge lines parallel to the traveling direction of the laser light is cut off to form at least one corner of the incident surface. 3. The shape is a substantially columnar shape, and the end surface of the cylinder into which the laser light enters or exits has at least one side that is cut out by a straight line, and the side is an electric field vector of an ordinary ray. An optical crystal that is parallel to the direction of, 90 degrees or 45 degrees. 4. The optical crystal body according to claim 3, wherein a part of the cylinder is cut out in a plane parallel to the traveling direction of the laser beam, so that the end face is provided with a side cut out in a straight line. 5. A semiconductor laser, a solid-state laser crystal body,
A semiconductor laser pumped solid-state laser device comprising a non-linear optical crystal body, and one or both of the solid-state laser crystal body and the non-linear optical crystal body being an optical crystal body having a shape according to claim 1.