JP2865057B2 - Laser diode pumped solid-state laser oscillator. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser diode (LD) pumped solid-state laser oscillator, and more particularly to various solid-state laser oscillators that emit infrared light having an oscillation wavelength in the 1 .mu.m to 3 .mu.m band, for example, neodymium: yag ( Nd: YA
G) Laser oscillator (oscillation wavelength 1.06 μm), holmium: yag (Ho: YAG) laser oscillator (oscillation wavelength 2.
1 μm) or Erbium: YAG (Er: YAG) laser oscillator (oscillation wavelength 2.9 μm), etc., or 0.7
a solid-state laser oscillator having an oscillation wavelength in the μm to 1 μm band,
For example, an Alexandrite laser oscillator or Cr: Li
It relates to a SAF laser oscillator and the like.

[0001]

2. Description of the Related Art Conventionally, in this type of LD-pumped solid-state laser oscillator, as disclosed in Japanese Patent Publication No. 7-28072, total reflection is provided on both end surfaces of a rod-shaped Nd: YAG crystal (laser rod). A mirror and an output mirror are arranged so as to sandwich the crystal. And Nd: YA
One end face of the G crystal is irradiated with excitation light output from a laser diode. The emission of Nd ions excited by the irradiation of the excitation light is amplified by reciprocating between the total reflection mirror and the output mirror. The amplified luminescence is
The light is output as laser oscillation light from the output mirror side.

[0002] This laser oscillator is generally called an end-pumped laser oscillator. The optical axis of the excitation light from the laser diode and the optical axis of the laser oscillation light are coaxial, so that the excitation efficiency is high. And a desired laser oscillation light can be obtained.

On the other hand, in an LD-pumped solid-state laser oscillator of the end-pumping method, a method of increasing the laser oscillation output is as follows.
Japanese Utility Model Publication No. 6-21261 and USP 4,710,94
0.

[0004] In this conventional laser oscillator, a plurality of laser rods are arranged in series, these are operated as a single laser rod, and the laser rods are excited using excitation light from a plurality of excitation laser diodes. Thereby, the output of the laser oscillation light is increased. Therefore, in the conventional laser oscillator, a folding mirror having a 45-degree inclination angle with respect to the laser oscillation light is provided on the end face side of the laser rod.

[0005]

However, in this conventional laser oscillator, the installation angle of the return mirror fluctuates due to the ambient temperature and heat generated by the laser diode, and changes the optical axis of the laser light. There is a problem that the light output becomes unstable.

Further, since the laser light is reflected by the return mirror, the output of the laser light is reduced by the reflection loss each time, and as a result, the laser oscillation efficiency is deteriorated.

[0007]

Means for Solving the Problems In order to solve the above problems, a laser diode-pumped solid-state laser oscillator according to the present invention comprises: a laser crystal formed by a crystal containing ions having a laser oscillation action; A prism formed of either a crystal or a glass material that does not include the laser crystal and optically bonded to the first end face of the laser crystal, and a laser crystal and the prism disposed inside to form a resonator A total reflection mirror and an output mirror ,
A first light source that irradiates the second end face of the laser crystal facing the first end face with the excitation light; and a second light source that irradiates the first end face of the laser crystal with the excitation light via the prism. . In addition, the prism is optically bonded to the laser crystal.
Has a Brewster angle at the position facing the bent end face
Excitation having a Brewster surface and output from a second light source
Light is reflected by the Brewster surface after entering the prism.
Then, the laser beam is irradiated on the first end face of the laser crystal.

[0008]

Next, a first embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a horizontal sectional view showing the structure of the first embodiment of the present invention, FIG. 2 is a simplified view of the structure shown in FIG. 1, and FIG. It is the figure which expanded and showed the principal part of the structure of this embodiment.

Referring to FIGS. 1 and 2, the excitation lights output from the laser diodes 3 and 4 having a rectangular light emitting area of 1 μm × several 100 μm are collimated by the collimating lenses 5 and 6 into parallel light. The excitation light that has passed through the collimating lenses 5 and 6 is not preferable for use in exciting a solid-state laser crystal because the cross-sectional shape of the beam is elliptical. Therefore, by passing the excitation light through the beam expanders 7 and 8, the beam shape is shaped into a circle. Then, the beam shape is shaped into a circle by the beam expander 7, and further,
The excitation light that has passed through the condenser lens 9 is incident on one end face of the laser crystal 1. On the other hand, the beam shape is shaped into a circle by the beam expander 8, and the excitation light that has passed through the condenser lens 10 enters the prism 2. In FIG. 2, the collimating lenses 5 and 6, the beam expanders 7 and 8, and the condenser lenses 9 and 10 are simply shown as a lens 21 for simplification of the drawing.

Here, the laser crystal and the prism will be described with reference to FIG. 3. The laser crystal 1 and the prism 2 are composed of an end face facing the end face on which the excitation light of the laser crystal 1 is incident and the excitation light of the prism 2. Is optically bonded to the end face where the light is not incident. A total reflection mirror 12 is provided on an end face of the laser crystal 1 where the excitation light is incident so as to transmit the excitation light and totally reflect the laser oscillation light. On the other hand, the prism 2 has a Brewster surface which is coated at a position facing the end face optically bonded to the laser crystal 1 so as to totally reflect only the wavelength of the excitation light and is inclined by the Brewster angle. 11 The laser crystal 1 is a Nd: YAG crystal, and the prism 2 is
This is a YAG crystal to which Nd is not added. The laser crystal 1 is not limited to the Nd: YAG crystal, but a crystal containing ions having a laser oscillation action at the center of the crystal, for example,
HO: YAG crystal, Er: YAG crystal or Cr: L
An iSAF crystal or the like may be used, and the prism 2 may be a crystal that does not include the above-described ions having a laser oscillation function or a glass material such as fused silica.

Returning to FIGS. 1 and 2, the description will be continued. The excitation light that has entered the prism 2 is reflected by the Brewster surface 11 and then enters the laser crystal 1. Excitation light from laser diode 3 and Brewster surface 1 of prism 2
When the pumping light reflected by the laser crystal 1 enters the laser crystal 1, the laser crystal 1 oscillates due to the action of the laser resonator constituted by the total reflection mirror 12 and the output mirror 14 provided on the end face of the laser crystal 1, and the light is emitted The amplified laser light is output from the output mirror 14 to the outside.

The laser diodes 3 and 4 include:
The radiation fins 15 are arranged and the laser diode 3
And 4, the fluctuation of the laser output due to the heating is prevented.

Further, the operation of the laser crystal and the prism will be described with reference to FIG.

The laser crystal 1 has an oscillation wavelength of 1.06 μm.
An Nd: YAG crystal having a refractive index of 1.8 m is used as the prism 2, a YAG crystal not containing Nd and having a refractive index of 1.83 is used. When a laser diode having the same is used, the excitation light from the laser diode 4 is incident on the excitation light incident surface 24 of the prism 2 along the excitation optical axis 23 at an incident angle of about 35.7 degrees. The excitation incident surface 24 is provided with an anti-reflection coating for light having a wavelength of 809 nm. The excitation light that has entered the prism 2 and has been totally reflected by the Brewster surface 11 has its optical axis set to the laser optical axis 2.
2. The Nd: YAG crystal is excited from the opposite direction to the excitation light from the laser diode 3. That is,
The laser crystal 1 is excited by excitation light incident from two opposing end faces. The laser optical axis 25 is the prism 2
The Brewster surface 11 has a Brewster angle of about 61 degrees. By making the light reflected by the output mirror 14 incident on the Brewster surface 11 at a Brewster angle, the reflection loss of light having a polarization direction (P-polarized light) component parallel to the incident angle can be minimized. it can.

Next, a second embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 4, the configuration of this embodiment is as follows.
A laser crystal 41 in which prisms 42 and 43 are optically bonded to both end surfaces with respect to the configuration of the first embodiment described above.
And two laser diodes 44 and 45 for exciting the laser crystal 41 thereof. Here, the laser diodes 44 and 45, the prisms 42 and 43, and the laser crystal 41 are equivalent to the laser diodes 3 and 4, the prism 2, and the laser crystal 1 in FIG. The pumping light from the pumping laser diode 44 passes through the condenser lens 21 and passes through the prism 42
And is reflected by the Brewster surface provided in the prism, and is incident on the laser crystal 41. On the other hand, the excitation light from the excitation laser diode 45 is incident on the prism 43 via the condenser lens 21, is reflected on the Brewster surface provided in the prism, and is incident on the laser crystal 41. The laser crystal 41 oscillates by pumping light incident from two opposing end faces, and amplifies the light.

In this embodiment, since a laser crystal is additionally provided, a larger laser output can be obtained. Further, since the laser light path is arranged not in a zigzag shape but in a straight line, the structure is simplified and the manufacture is facilitated.

In this embodiment, a configuration in which two laser crystals are arranged in series has been described. However, the number of laser crystals to be used is not limited to two. In consideration of the relationship, it is preferable to arrange an optimal number of laser crystals. Further, as the number of laser crystals increases, the number of pumping laser diodes and prisms also increases.

Next, a third embodiment of the present invention will be described with reference to FIG.

Referring to FIG. 5, this embodiment differs from the first embodiment in that a nonlinear optical crystal for converting the laser oscillation wavelength to １ ／, such as a nonlinear optical crystal, is provided inside a resonator that performs laser oscillation. SHG (Second Harmoni
c Generation) crystal 51 is arranged. Further, as an output mirror, a two-wavelength total reflection mirror 52 having a reflectance of 100% at both wavelengths of laser light and light whose wavelength has been converted to half by the SHG crystal (SHG light) is disposed. The SHG crystal 51 is arranged between a total reflection mirror provided on one end face of the laser crystal and a two-wavelength total reflection mirror, and converts laser light inside the resonator into SHG light. The converted light is output in both directions of the SHG crystal, that is, in the direction of the prism and in the direction of the two-wavelength total reflection mirror. One light is reflected and reflected by the two-wavelength total reflection mirror, and as a result, both lights are incident on the Brewster surface 11 of the prism. The light incident on the prism 2 is reflected by the Brewster surface 11 and is extracted as a laser light output in the direction of the arrow 53. That is, in the present embodiment, laser light can be output from the end surface (Brewster surface) of the prism.

[0022]

As described above, in the laser diode-pumped solid-state laser oscillator of the present invention, it is not necessary to provide a folding mirror as a configuration for increasing the laser output. It is possible to prevent the optical path of laser oscillation from fluctuating due to factors. As a result, a stable laser output can be obtained.

Furthermore, the number of optical surfaces through which laser light passes is greatly reduced as compared with the case where a folding mirror is used, so that the efficiency of laser oscillation can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a simplified diagram of the configuration of FIG.

FIG. 3 is a diagram showing a configuration of a main part of FIG. 1;

FIG. 4 is a schematic diagram illustrating a configuration of a second exemplary embodiment of the present invention.

FIG. 5 is a schematic diagram illustrating a configuration of a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 41 Laser crystal 2, 42, 43 Prism 3, 4, 44, 45 Laser diode 5, 6 Collimating lens 7, 8 Beam expander 9, 10 Condensing lens 11 Brewster surface 12 Total reflection mirror 14 Output mirror 15 Heat radiation Fin 21 Condensing lens 51 SHG crystal 52 Two-wavelength total reflection mirror

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01S 3/0941 H01S 3/06 H01S 3/08 H01S 3/108-3/109

Claims (4)

(57) [Claims] 1. A first laser crystal formed by a first crystal containing ions having a laser oscillation action, and a second crystal or a glass material not containing the ions, A first prism optically bonded to a first end face of the one laser crystal;
A total reflection mirror and an output mirror that form a resonator by disposing the first laser crystal and the first prism therein; and a second mirror that faces the first end face of the first laser crystal. Les comprising a first light source for irradiating excitation light on the end face, and a second light source for irradiating excitation light to the first end surface of said through first prism first laser crystal
In the laser diode pumped solid-state laser oscillator, the first prism is optically bonded to the laser crystal.
Has a Brewster angle at the position facing the
Excitation light output from the second light source has a Brewster surface.
After entering the rhythm, it reflects off the Brewster surface,
A laser diode-pumped solid-state laser oscillator, which irradiates the first end face of the first laser crystal . 2. The method according to claim 1 , further comprising the steps of :
A first laser crystal formed by the first crystal;
Either a second crystal or glass material that does not contain ON
And a first laser crystal of the first type.
A first prism optically bonded to the end face,
The first laser crystal and the first prism
-Reflection mirror and output arranged in a cavity to form a resonator
A mirror paired with the first end face of the first laser crystal;
A first light source for irradiating the second end face facing the first excitation light with excitation light;
The first laser crystal passes through the first prism.
A second light source for irradiating the first end face with excitation light.
A laser diode-pumped solid-state laser oscillator, the first laser crystal being formed of the first crystal;
A second laser arranged to form the same optical axis with respect to
Laser crystal and either the second crystal or the glass material
And the second laser crystal is opposed to each other.
Second and third optically bonded ends on the two end faces.
Rhythm and one of the second laser crystals via the second prism.
A third light source for irradiating the end face with excitation light, and another light source for the second laser crystal via the third prism.
And a fourth light source for irradiating the end surface of the light source with the excitation light.
A solid-state laser oscillator pumped by a laser diode. 3. The method according to claim 1, wherein said ion is neodymium ion,
Selected from Mium or Erbium ions
3. An ion as claimed in claim 1, wherein
2. A laser diode-pumped solid-state laser oscillator according to claim 1. 4. The method according to claim 1 , further comprising the steps of :
A first laser crystal formed by the first crystal;
Either a second crystal or glass material that does not contain ON
And a first laser crystal of the first type.
A first prism optically bonded to the end face,
The first laser crystal and the first prism
-Reflection mirror and output arranged in a cavity to form a resonator
A mirror paired with the first end face of the first laser crystal;
A first light source for irradiating the second end face facing the first excitation light with excitation light;
The first laser crystal passes through the first prism.
A second light source for irradiating the first end face with the excitation light;
The first prism is optically bonded to the laser crystal.
Has a Brewster angle at the position facing the bent end face
It has a Brewster surface and is output from the second light source
After the excitation light is incident on the first prism, the excitation light
The first laser crystal reflected by the first laser crystal.
Laser diode-pumped solid-state laser irradiating the end face of 1
An oscillator disposed on an optical axis of a laser beam inside the resonator;
A nonlinear optical crystal that converts the oscillation wavelength of laser light to half
The output mirror further includes the laser light and the non-linear optics.
Total reflection of both wavelength-converted light by the crystal
Characteristic laser diode pumped solid-state laser oscillator.