JPH04322480A - Solid-state laser device - Google Patents

Abstract

PURPOSE:To achieve that a laser medium for a solid-state laser device absorbs excitation light effectively, to prevent an output from becoming unstable due to a thermal lens phenomenon and to stabilize a laser output. CONSTITUTION:A filter layer 10 which reflects only a wavelength in an absorption band for a laser medium 4 out of light radiated by a light source 3 is formed on the surface of a reflection face 2 in a cavity 1. Thereby, only a wavelength region which is easily absorbed by the laser medium out of light radiated from the light source 3 is reflected, and the output of a solid-state laser device is stabilized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state laser device excited by light from a flash lamp or arc lamp used in industrial or medical equipment.

0002

2. Description of the Related Art In recent years, solid-state laser devices have been used as industrial machines, and in the semiconductor field, fields of use have been expanding year by year, including device trimming, scribing, marking, soldering, welding, and cutting. In the medical field, its use as a therapeutic device is rapidly expanding.

A conventional solid-state laser device will be explained below with reference to the drawings. 4 and 5 show the configuration of a conventional solid-state laser device excited using light from a flash lamp or an arc lamp.

As shown in FIG. 4, a structure (hereinafter referred to as a cavity) has a reflective surface 2 that reflects lamp light inside.
A light source 3 using a flash lamp or an arc lamp consisting of a xenon lamp or a krypton lamp is provided inside the pump 1 to constitute an excitation light source.

On the other hand, a laser section is composed of a laser medium 4 and a laser medium protection tube 5 that protects it. The excitation light source 3 is housed in a flow tube 6 for improving the cooling effect of a cooling medium, and the cooling medium cools the heat generated by the lamp light, and the entire laser device is inside this cooling medium.

The operation of the laser device configured as described above will be explained below. Excitation light emitted from the light source 3 enters the laser medium 4 and is absorbed. The light that has passed through without being absorbed is reflected by the reflecting surface 2 and enters the laser medium 4 again. The absorbed light energy is shown in Figure 5.
An optical resonator surrounded by a partial reflecting mirror 7 and a total reflecting mirror 8 shown in FIG.

At this time, the optical absorption coefficient of the laser medium 4 has a strong wavelength dependence, and the wavelength range 7 is effective for laser oscillation.
It is effective for laser oscillation that wavelengths of 50 nm to 810 nm are effectively absorbed by the laser medium. Figure 6 shows the xenon lamp emission spectrum, and Figure 7 shows the crypto lamp emission spectrum. As can be seen from the figure, the light generated by flash lamps and arc lamps includes light in a wide wavelength range. Among these, light with a wavelength other than that effective for laser oscillation becomes thermal energy, causing a rise in the temperature of the laser device. Then, it is necessary to increase the cooling capacity of the cooling medium by the amount of heat, which is a negative factor for some laser devices.

[0008]

[Problems to be Solved by the Invention] However, with such a conventional configuration, it is difficult to make the laser medium 4 absorb light effectively, and furthermore, since the unabsorbed light becomes heat, the cooling ability of the cooling medium is reduced. If you don't design it big,
There was a problem in that the temperature of the laser medium 4 increased and a thermal lens phenomenon occurred in the laser medium 4, making it difficult to obtain a laser device with stable laser output.

The present invention solves these problems, and provides a solid-state laser device that can efficiently absorb light from a light source, improves laser oscillation energy, and is also thermally stable. The purpose is to

0010

[Means for Solving the Problems] In order to achieve this object, the solid-state laser of the present invention has a wavelength range that is absorbed by the laser medium on the reflective surface of the cavity when the laser medium absorbs the light from the excitation light source. It has a filter layer that reflects light.

[0011]

[Operation] With this configuration, among the light emitted from the excitation light source and reflected by the reflective surface on the inner surface of the cavity, only the light having a wavelength that is absorbed by the laser medium is reflected by the filter layer, and the energy radiated from the light source is is efficiently absorbed by the laser medium. Therefore, the temperature rise of the laser medium is reduced, the cooling medium is sufficiently cooled, and a thermally stable solid-state laser can be obtained.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A solid-state laser device according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a solid-state laser device according to an embodiment of the present invention. In this embodiment, the same components as in the conventional example are designated by the same numbers and the explanation thereof will be omitted.

As shown in the figure, an excitation light source 3 equipped with a lamp such as a xenon lamp or an arc lamp is provided inside the cavity 1. On the other hand, the laser medium 4 and
A laser section is constituted by a protective tube 5 that protects the laser section. The excitation light source 3 is housed in a flow tube 6 and is cooled by a cooling medium. A filter layer 10 is formed on the reflective surface 2 on the inner surface of the cavity, and reflects only light of a wavelength that is absorbed by the laser medium 4 to be incident on the laser medium 4 .

Regarding the resonator configured as above,
The operation will be explained with reference to FIGS. 1 to 3.

The excitation light emitted from the light source 3 enters the laser medium 4 either directly or after being reflected by the inner surface 1 of the cavity. At this time, the energy absorbed by the laser medium 4 is expressed by the following equation 1.

ΣE=ΣA×ΣB …………… Equation 1 ΣE: Energy absorbed by the laser medium ΣA: Output efficiency of excitation light ΣB: Input efficiency of excitation light In this formula 1, ΣA is the output efficiency of excitation light and the cavity 1 and the arrangement of the laser medium 4 and the light source 3. ΣB is the incidence efficiency of the excitation light, which is determined by the reflectance or absorption of the reflecting surface 2 of the cavity 1, the laser medium 4, the flow tube 5, and the cooling medium, and is expressed by Equation 2.

ΣB=K×(1-R)×(1-S)×(1-F)×
(1-W) ... Equation 2K: Absorption rate of laser medium R: Absorption rate by cavity S: Absorption rate by flow tube F: Absorption rate by laser medium protection tube W: Absorption rate by cooling medium In Equation 2, ΣB is excitation It changes depending on the wavelength of light. The wavelength of the excitation light emitted from the light source 3 has a very wide wavelength range, as shown in FIGS. 6 and 7, but the main absorption wavelengths of the laser medium 4 are 530, 580, and 750, as shown in FIG. ，
It is at 810,880 nm. Among these, particularly strong absorption is in the range of 750 to 810 nm, so by adjusting the wavelength of the light emitted from the light source 3 to this absorption band using a filter having the absorption characteristics shown in FIG. Effectively absorbed. By forming a filter layer 10 on the reflective surface 2 of the cavity 1 that reflects only wavelengths that are easily absorbed by the laser medium 4, the cavity 1
It is possible to reduce unnecessary heat generated inside the device and increase the cooling effect. Furthermore, since the laser medium 4 efficiently absorbs the incident light, instability of the oscillation state due to the thermal lens phenomenon that occurs when the excitation energy becomes large can be prevented, and the laser output can be stabilized. This effect is
Limited to the main absorption wavelength band of the laser medium 4, especially 550n
By forming a filter layer that reflects only wavelengths from m to 900 nm, significant effects can be obtained, such as the ability to eliminate the adverse effects of ultraviolet rays on laser oscillation.

[0019]

As is clear from the above description of the embodiments, according to the present invention, a filter layer is provided on the reflective surface of the cavity to reflect only light in a specific wavelength range corresponding to the light absorption characteristics of the laser medium. By forming such a structure, lamp energy is efficiently absorbed by the laser medium, and a solid-state laser device having stable output characteristics without thermal lens phenomenon can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a solid-state laser device according to an embodiment of the present invention.

[
Figure 2: Absorption spectrum of the same laser medium

[Figure 3] Absorption spectrum of the same filter layer

[Figure 4] Cross-sectional view of a conventional solid-state laser device

[Figure 5] Configuration diagram of the solid-state laser device

[Figure 6] Emission spectrum of xenon lamp

[Figure 7] Emission spectrum of krypton lamp

[Explanation of symbols]

1 Cavity 2 Reflective surface of cavity 3 Light source 4 Laser medium 5 Laser medium protection tube 6 Flow tube 10 Filter layer

Claims (2)

[Claims] Claim 1: A solid-state laser that oscillates by exciting a solid-state laser medium with a light source such as a flash lamp or an arc lamp, in which the light source and the laser medium are arranged in parallel, and the excitation light emitted by the light source is placed outside of the laser medium. 1. A solid-state laser device comprising: a cavity having a reflective surface that reflects light; the reflective surface has a filter layer that reflects only a wavelength that is absorbed by the laser medium out of the light emitted by the light source. Claim 2: The filter layer has a wavelength of 550nm to 900nm.
2. The solid-state laser device according to claim 1, which reflects only m light.