JP3003172B2 - Solid state laser oscillator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a solid-state laser oscillator.

[Summary of the Invention]

The present invention relates to a solid-state laser oscillator including a laser resonator including a pair of mirrors and a solid-state laser medium disposed between the pair of mirrors, and an excitation light source that generates pumping light for exciting the solid-state laser medium. A plurality of pumping light sources are provided, a plurality of pumping lights from the plurality of pumping light sources are irradiated to a plurality of portions of the solid-state laser medium, a plurality of thermal lenses are formed on the laser medium, and a pair of mirrors and a pair of mirrors are formed. By forming a plurality of laser resonator sections with a solid laser medium and a plurality of thermal lenses disposed between a pair of mirrors, a simple configuration can be achieved with high excitation efficiency and high output.

[Conventional technology]

Some solid-state laser oscillators excite a solid-state laser medium of a laser resonator comprising a pair of mirrors and a solid-state laser medium disposed between the pair of mirrors by pumping light from a semiconductor laser (laser diode). However, this excites only the excitation level of the laser medium and selectively excites only the oscillation region of the laser medium, so that the excitation efficiency becomes extremely high.

Further, the laser light from a plurality of laser diodes is made incident on each optical fiber constituting the optical fiber bundle, and a bundle of laser light from the other end of the optical fiber bundle is irradiated on the laser medium as pumping light. There are also high-power solid-state laser oscillators.

[Problems to be solved by the invention]

In such a solid-state laser oscillator, if the number of optical fibers constituting an optical fiber bundle is increased, laser light emitted from a large number of laser diodes is bundled, and the laser light of this bundle is irradiated on a laser medium as pumping light, the output increases. However, as the diameter of the pumping light increases, the excitation efficiency of the fundamental mode of laser oscillation deteriorates.

Therefore, if the laser medium is excited by dividing the pumping light for exciting the laser medium into a plurality of light beams instead of one thick light beam, the excitation efficiency of the fundamental mode of laser oscillation does not deteriorate.

However, in such a case, it is necessary to provide output mirrors (concave mirrors) corresponding to the number of light beams of the pumping light, which is not practical.

In view of such a point, the present invention intends to propose a solid-state laser oscillator having high excitation efficiency and high efficiency with a simple configuration.

[Means for solving the problem]

The present invention provides a laser resonator including first and second mirrors and a solid-state laser medium disposed between the first and second mirrors, and irradiates from the first mirror to excite the solid-state laser medium. A solid-state laser oscillator having an excitation light source for generating pumping light and emitting output laser light from a second mirror side, wherein a light-transmissive heat sink provided on the first mirror side of the laser medium; A light source and a plurality of excitation light sources for emitting laser light from the plurality of laser light sources to one end thereof; and a plurality of excitation light sources for emitting pump light from the other end of the optical fiber means. Are transmitted through the light-transmitting heat sink and the first mirror, and are applied to a plurality of portions of the laser medium, so that the laser medium has a plurality of heat pumps. Is formed, a plurality of laser resonators are formed by the first and second mirrors, the solid-state laser medium disposed between the first and second mirrors, and the plurality of thermal lenses, and the plurality of laser resonators are formed. The interval between the plurality of irradiation positions of the plurality of pumping lights with respect to the laser medium is set so that the interval between the output laser lights is such that the tails of the respective Gaussian distributions of the plurality of output laser lights overlap. This is a solid-state laser oscillator.

[Action]

According to the present invention, a plurality of laser light sources and a plurality of pumps for emitting pumping light from the other end of the optical fiber means are provided with the plurality of laser light sources and the optical fiber means to which laser light from the plurality of laser light sources is incident on one end. A plurality of pumping lights from a light source are transmitted through the light-transmitting heat sink and the first mirror, and are applied to a plurality of portions of the laser medium to form a plurality of thermal lenses on the laser medium. The two mirrors, the solid-state laser medium disposed between the first and second mirrors, and the plurality of thermal lenses constitute a plurality of laser resonators, and the interval between the plurality of output laser beams is The interval between the irradiation positions of the plurality of pumping lights on the laser medium at a plurality of positions is set so that the intervals of the Gaussian distributions of the plurality of output laser lights overlap. To set.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. (23) is a cylindrical solid laser medium (laser rod) (Nd: YAG), and flat mirror coats (24) and (25) are formed on both end surfaces thereof. Mirror coat (24) is a pumping light L _1, L _2, L ₃ is transmitted through substantially 100%, is a mirror that reflects substantially 100% of the oscillation laser beam.
Mirror coat (25) is a few percent to 10 percent of the oscillating laser light
Is a mirror that reflects light and transmits the rest.

A disc-shaped light transmissive heat sink (30) made of diamond, sapphire, or the like having a higher thermal conductivity than the laser medium (23) is provided on the incident side of the pumping light of the laser medium (23) via a mirror coat (24). ) Is attached. An anti-reflection coating (31) is formed on the surface of the disc-shaped heat sink (30) in order to reduce optical loss due to the heat sink (30).

By providing the heat sink (30) in this way,
The temperature distribution in the radial direction of the laser medium (23) is reduced,
Since unnecessary heat absorption difference, thermal birefringence, etc. are suppressed,
The output becomes even higher.

(35), (36) and (37) are three pumping light sources, which are semiconductor lasers (laser diodes) (1) to (5), respectively.
(6) to (10), (11) to (15) and the laser light emitted from each of these laser diodes are transmitted,
Bundled together, three optical fiber bundles (18),
It is composed of 15 optical fibers (17) constituting (19) and (20) and their optical fiber bundles (18), (19) and (20).

Then, divergent laser light (pumping light) L ₁ , L ₂ from each end of each optical fiber bundle (18), (19), (20) of each excitation light source (35), (36), (37) , L ₃ are incident on the convex lens (21), are converted into substantially parallel light, and then are focused by being incident on the other convex lens (22),
Laser medium (23) through mirror coat (24) to focus on different parts of laser medium (23)
Is irradiated.

Thus, the vicinity of the portion of the laser medium (23) irradiated with each pumping light is heated to form thermal lenses (26), (27) and (28), respectively. The laser medium (23), the mirror coats (24) and (25) and the thermal lenses (26), (27) and (28) form three resonators (3).
9), (40) and (41) are formed.

Then, in the laser medium (23), three fundamental mode oscillation laser lights unique to the laser medium (23) are generated, and are repeatedly reflected by the mirror coats (24) and (25) and transmitted back and forth. And the thermal lens (2
6), (27), and (28) are repeatedly passed, and a part of the laser light is output to the outside as output laser light L ₄ , L ₅ , and L ₆ through the output mirror coat (25). At this time, the thermal lenses (26), (27), (28) and the mirror coat (25) work together to form a flat output mirror coat (2).
This is equivalent to providing three concave mirror coats instead of 5).

3 from the mirror coat (25) side of the laser medium (23)
The interval l between the optical axes of the output laser lights L ₄ , L ₅ , L ₆ (fundamental mode oscillation lens light) is set so that the Gaussian distribution of each output laser light (fundamental mode oscillation laser light) overlaps to some extent. Three pumping lights L ₁ ,
If the distance between the three irradiation positions with respect to the L ₂ L ₃ laser medium (23) is set, the three resonator units (39), (4
A phase pull-in occurs between 0) and (41), phase synchronization becomes possible, and a diffraction-limited output laser beam is output.
In this case, three resonator units (39), (40), and (41)
It is necessary that the optical path lengths of the lasers are equal, but if there is some difference, the output of the pumping light from the pump light sources (35), (36) and (37) is It may be changed by adjustment.

According to the solid-state laser oscillator of this embodiment, the pumping efficiency is high and the output is high with a simple configuration.

〔The invention's effect〕

According to the present invention described above, a laser resonator including a first and a second mirror and a solid-state laser medium disposed between the first and the second mirrors, and a solid-state laser irradiated from the first mirror side A solid-state laser oscillator having an excitation light source that generates pumping light for exciting the medium, and an output laser light emitted from the second mirror side; a light-transmitting heat sink provided on the first mirror side of the laser medium; Each comprising a plurality of laser light sources and optical fiber means to which laser light from the plurality of laser light sources is incident on one end, and having a plurality of excitation light sources for emitting pumping light from the other end of the optical fiber means, A plurality of pumping lights from a plurality of excitation light sources are transmitted through the light-transmitting heat sink and the first mirror, and are applied to a plurality of portions of the laser medium. A plurality of thermal lenses formed in the heat medium, and a plurality of laser resonators formed by the first and second mirrors, the solid-state laser medium disposed between the first and second mirrors, and the plurality of thermal lenses. And irradiating positions of the plurality of pumping lights on the laser medium at a plurality of positions so that the interval between the plurality of output laser lights is such that the skirts of the respective Gaussian distributions of the plurality of output laser lights overlap. Since the interval between them is set, the simple configuration, high excitation efficiency and high output,
Moreover, by providing a light transmissive heat sink,
Since the temperature distribution in the radial direction of the laser medium is reduced and unnecessary heat absorption difference, thermal birefringence, etc. are suppressed, the output becomes higher, and phase pull-in occurs between a plurality of resonators. Thus, a solid-state laser oscillator capable of performing phase synchronization and outputting a diffraction-limited output laser beam can be obtained.

[Brief description of the drawings]

FIG. 1 is a layout diagram showing an embodiment of the present invention. (1) to (15) are laser diodes, (16) is a substrate,
(17) is an optical fiber, (18), (19) and (20) are optical fiber bundles, (21) and (22) are convex lenses, (23) is a laser medium, (24) and (25) are mirror coats , (26)-
(28) is a thermal lens, (30) is a heat sink, and (31) is a non-reflective coating.

Claims (1)

(57) [Claims] 1. A laser resonator comprising first and second mirrors and a solid-state laser medium disposed between said first and second mirrors, and said solid-state laser medium irradiated from said first mirror side. A solid-state laser oscillator having an excitation light source for generating pumping light for exciting light, and an output laser light emitted from the second mirror side, wherein a light-transmitting heat sink provided on the first mirror side of the laser medium. And a plurality of excitation light sources, each comprising a plurality of laser light sources and optical fiber means to which laser light from the plurality of laser light sources is incident at one end, and emitting pump light from the other end of the optical fiber means. Transmitting a plurality of pumping lights from the plurality of excitation light sources through the light-transmitting heat sink and the first mirror,
By irradiating a plurality of portions of the laser medium to form a plurality of thermal lenses on the laser medium, the first and second thermal lenses are formed.
And a plurality of laser resonators formed by the solid laser medium and the plurality of thermal lenses disposed between the first and second mirrors, and the distance between the plurality of output laser beams is An interval between the plurality of irradiation positions of the plurality of pumping lights with respect to the laser medium is set such that the intervals of the Gaussian distributions of the plurality of output laser lights overlap with each other. Characterized solid-state laser oscillator.