JPH02146781A - Laser diode excitation solid laser - Google Patents

Abstract

PURPOSE:To make power of outgoing laser beam changeable without changing power of excitation LD light, while making alignment control in accordance with power fluctuation of the excitation LD light unnecessary by providing a light damper on the outside of a light resonator. CONSTITUTION:Excitation light 6 going out from LD 1 is focused by a coupling optical system 2 such as a focusing lens and guided to a laser rod 3. The laser rod 3 and an output mirror 5 forms a light resonator. Outgoing laser light 7 emitted from this light resonator passes through a damper 10 while receiving damping according thereto to go out from a laser head 9. As the damper 10, in addition to a solid filter such as an ND filter, an interference filter, a variable filter, whose transmission factor is in a space two-dimensionally changing, and a variable filter, whose transmission factor is electrooptically changing, can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a laser diode pumped solid state laser.

[Conventional technology] Compared to conventional lamp-pumped lasers, laser diode (LD)-pumped solid-state lasers have a longer excitation light source life and have almost no thermal influence on the laser medium, so there is no need for water cooling. , which is attracting attention as a compact and long-life all-solid-state laser. In addition, the above-mentioned LD is currently well known as an all-solid-state laser, but the L
D has problems such as the spatial output shape of the laser beam being elliptical and instantaneous edge destruction, but with LD-pumped solid-state lasers, these problems have been resolved and the lifetime at the excited level is long. It has features such as being able to store energy and obtaining high peak output through Q-switch operation. Therefore, LD pumped solid-state lasers are expected to be applied in various fields.

[Problems to be Solved by the Invention] By the way, when using a conventional LD-excited solid-state laser while stably changing its optical output, there are the following problems.

Conventionally, when changing the optical output and using the desired output, this was done by changing the optical output of the LD, which is excitation light, that is, the current flowing through the LD.

However, in this case, there is a problem that a change in the current flowing through the LD changes its heat generation state, and as a result of the temperature change, the optical output becomes unstable. Furthermore, at this time, there was a problem in that it was difficult to adjust the alignment of the optical resonator etc. so that the optical output was stable over the entire power range of the pumping light.

This will be explained below with reference to FIG. 2, which shows a conventional example. In the figure, ■ is a laser diode (LD), 2 is a coupling optical system such as a condenser lens, 3 is a laser rod, 5 is an output mirror, 6 is an excitation LD beam, 7 is an output laser beam, 8 is a Vertier element, 9 is a It's a laser head.

4, a nonlinear optical crystal may be installed between the laser rod 3 and the output mirror 5.

As shown in Figure 2, in the conventional example, a laser diode
1, there is no means for adjusting the light intensity on the output side, so the adjustment of the output laser beam 7 is the adjustment of the excitation LD light 6, that is, the L
This is done by adjusting the current flowing through D1. When this adjustment is performed, the amount of heat generated by the LD 1 changes, so the power of the excitation LD light beam 6 becomes unstable, and it takes a considerable amount of time to stabilize it. Furthermore, in order to obtain the output laser beam 7 most efficiently using the power of the excitation LD beam 6, the alignment of the coupling optical system 2, laser rod 3, output mirror 5, and Vertier element 8 must be adjusted (
Since this is not the case, the effort is necessary. Furthermore, in order to obtain a low-power output laser beam 7, the LD must be driven near the oscillation threshold, resulting in significant instability.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and provides an LD pumped solid-state laser characterized in that an optical attenuator is provided outside the optical resonator. It provides a pumped solid-state laser.

[Example] Embodiments of the present invention will be explained below.

FIG. 1 is a diagram showing an example of the basic configuration of the present invention, and the numbers in the diagram represent the same ones as in FIG. 2 described above. Also, 1
0 indicates an attenuator.

The excitation LD light beam 6 emitted from the LD 1 is condensed by a converging optical system 2 such as a condensing lens, and guided to a laser rod 3. The end face of the laser rod 3 near the LD 1 is coated with a non-reflection coating, so that the excitation LD light beam 6 can be efficiently guided into the laser rod 3. On the other hand, a high-reflection coating for the oscillation light of the solid-state laser is applied to the lower layer of the non-reflection coating on the end face of the laser rod 3 near the LD 1, which causes light resonance with the output mirror 5. In other words, in FIG. 1, the laser rod 3 and the output mirror 5
and form an optical resonator. The emitted laser beam 7 emitted from this optical resonator passes through an attenuator 10, receives corresponding attenuation, and is emitted from the laser head 9.

Here, the power of the excitation LD light beam 6 is set in consideration of the lifetime of the LD, and is driven at the power that can drive the LD with the highest efficiency and a long lifetime. In addition, the alignment of the coupling optical system 2, laser rod 3, output mirror 5, and Vertier element 8 is adjusted so that the output laser beam 7 can be extracted most efficiently in this state.

The attenuator 10 may include fixed filters such as ND filters and interference filters, as well as variable filters whose transmittance changes in a quadratic manner in space, and variable filters whose transmittance changes electro-optically. can also be used.

When using a fixed filter, use the laser head 9
By making it possible to insert and remove the filter, it becomes possible to perform variable output in two stages per fixed filter. Furthermore, when the variable filter described above is used, by inserting and removing the filter or rotating it, it becomes possible to perform variable output over several steps or continuously.

Furthermore, if a variable filter whose transmittance can be electro-optically varied is used, the output can be varied continuously.

By adopting such a configuration, it is possible to change the power of the output laser beam 7 without changing the power of the pump LD beam 6 (the power of the output laser beam 7 can be changed). No stabilization occurs, and there is no need to adjust the alignment of the coupling optics 2, laser rod 3, output mirror 5 and Vertier element 8 in order to obtain the most efficient output laser beam 7.

The position of the attenuator 10 is different from that in FIG. 1, and the effect of the present invention is produced even between the LD and the resonator. However, in that case, when changing the power of the emitted laser beam, the resonance state within the optical resonator is changed, so the configuration shown in FIG. 1 is not effective. Therefore, as shown in FIG. 1, it is preferable to install the attenuator IO on the outside opposite to the LD when viewed from the optical resonator. Further, although the attenuator is installed inside the laser head in FIG. 1, it is equally effective to install it outside the laser head.

In FIG. 1, the laser resonator is composed of a laser rod 3 and an output mirror 5, but another mirror is provided between the coupling optical system 2 and the laser rod 3, and this mirror and the output mirror 5 constitute the laser resonator. You may. Alternatively, as shown by the broken line in FIG. 1, a nonlinear optical crystal 4 may be inserted into an optical resonator to generate higher harmonics.

Further, although FIG. 1 shows a directly coupled LD-excited solid-state laser including an LD in the laser head 9, a fiber-coupled LD-excited solid-state laser in which LD light is guided through an optical fiber may also be used.

In addition, 1) - The material of the rod 3 is YAG, YL.
F, YAP, GGG and many other laser crystals and laser glasses can be used.

[Effects of the Invention] According to the present invention, the power of the emitted laser beam can be changed without changing the power of the excitation LD beam. Therefore, the power of the output laser beam does not become unstable due to the power fluctuation of the excitation LD beam, and the alignment of the coupling optical system, laser rod, output mirror, and Vertier element is adjusted in order to obtain the output laser beam most efficiently. There's no need to.

Furthermore, even when trying to obtain an LD in a low power range, there is no need to drive the LD near the oscillation threshold, and instability will not occur.

Furthermore, if an attenuator that absorbs or reflects nearly 100% of light is used, it can also be used as a shutter. For example, if you temporarily stop using a laser and then immediately restart it, the conventional method is to turn the LD light source on and off, but this method waits until the heat generation of the LD stabilizes. There was a need. However, according to the present invention, since the light can be turned on and off using an optical attenuator, the stable LD light source can be used as it is, and the above-mentioned time loss can be eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an example of the basic configuration of the present invention, and FIG. 2 shows a conventional example. 1 is a laser diode, 2 is a coupling optical system such as a condenser lens, 3 is a laser rod, 4 is a nonlinear optical crystal 5 is an output mirror, 6 is an excitation LD beam, 7 is an output laser beam, 8 is a Vertier element, 9 is a laser head, and 10 is an attenuator.

Claims (1)

[Claims] A laser diode-pumped solid-state laser characterized in that an optical attenuator is provided outside an optical resonator in the laser diode-pumped solid-state laser.