JP3471038B2 - Titanium sapphire laser oscillator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a titanium sapphire laser oscillation device. [0002] Conventionally, in the wavelength selection of a titanium sapphire laser oscillation device having a wide oscillation range from 650 nm to 1100 nm, a prism as a wavelength selection element is used.
A method of inserting a birefringent filter, a diffraction grating, or the like into a resonator has been used. In particular, a method is used in which a plurality of prisms and birefringent filters having relatively small insertion loss are inserted to narrow the oscillation wavelength width. See “Ti
tanium saphire lasercharacteristics, APPL.Opt, 27,1
3,1988 "will be described with reference to FIGS. FIG. 3 shows a conventional example in which a solid-state laser medium made of rod-shaped titanium sapphire provided on the optical path of the excitation laser light and a high-reflection mirror provided on one end side of the solid-state laser medium (2).
(3) and a first and a second light source provided between the high-reflection mirror (3) and the solid-state laser medium (2), and provided to guide the excitation laser light (1) to one end of the solid-state laser medium. 2 Brewster dispersion prisms (4) and (5) and a high-reflection mirror (3) and an output mirror (6) provided on the other end of the solid-state laser medium (2) to form an optical resonator. Configuration. In the configuration of FIG. 3, the high-reflection mirror (3) deviates from the optical path incident on the first Brewster dispersion prism (4), reflects from the output mirror (6), and outputs the solid-state laser medium (2), the second and the second laser. 1 Buster dispersion prism (5),
An optical path (7) indicated by a broken line in the figure refracted through (4) is rotatably provided so that the reflection angle can be adjusted for wavelength selection. Another conventional example shown in FIG. 4 is a solid laser medium (8) made of rod-shaped titanium sapphire and an excitation laser beam (9) at one end of the solid laser medium (8). A high-reflection mirror (10) that is provided substantially coaxially and that transmits the excitation laser light (9);
The birefringent filter (1
1) and a high-reflection mirror (10) with this birefringent filter (11) in between
And an output mirror (12) forming an optical resonator. In the prior art shown in FIG. 3, first and second Brewster dispersion prisms, which are wavelength selection elements, are used.
Since (4) and (5) are provided, and in the conventional example of FIG. 4, a birefringent filter (11), which is a wavelength selection element, is provided, internal loss cannot be avoided in any case, and the laser oscillation efficiency is reduced. Was. In addition, the insertion of the wavelength selection element increases the cavity length, increases the cavity mode diameter inside the optical resonator, and similarly reduces laser oscillation efficiency. SUMMARY OF THE INVENTION It is an object of the present invention to provide a titanium sapphire laser oscillation device which has a small internal loss, can easily control wavelength selection, and can be configured compactly. An excitation light source for outputting an excitation laser beam, and a phase conjugate provided in an optical path of the excitation laser beam and transmitting the excitation laser beam. A mirror,
A dispersive prism type in which two surfaces forming the apex angle are Brewster surfaces, and an incident angle between one of the Brewster surfaces and the excitation laser light incident on this surface is set at the Brewster angle. A Brewster dispersion prism provided with an incident angle of Brewster angle in an optical path passing through the laser medium, and a phase medium provided in an optical path passing through the Brewster dispersion prism. It comprises an output mirror forming a conjugate mirror and an optical resonator, and a drive means for driving the transmitted light passing through the laser medium in a direction in which the optical path length changes, and wavelength selection is performed by the laser medium itself. Hereinafter, the present invention will be described with reference to the drawings showing embodiments. FIG. 1 shows an embodiment of the present invention which is an end pump type. (20) is a Brewster dispersion prism, Nd:
The excitation laser light (22) output from the excitation light source (21) for outputting the second harmonic (532 nm) of the YAG laser or the argon ion laser is supplied to the Brewster dispersion prism (2).
0) is relatively positioned so as to be incident on one of the rectangular surfaces at a Brewster angle and exit from the other rectangular surface. A laser medium (23) made of titanium sapphire and cut into a Brewster dispersion prism is provided in an optical path passing through the Brewster dispersion prism (20). With this laser medium (23), a laser whose wavelength is variable between 650 nm and 1100 nm can be obtained. Considering wavelength selection or wavelength control near the maximum gain, as shown in FIG. Refractive index 1.7 at 810 nm to be maximum
From 577, a Brewster incident angle of 60.363 degrees is obtained.
Thus, a triangular prism having an apex angle of 59.274 degrees is formed. Therefore, the laser medium (23) is
The light (21) is provided so that the incident angle θ is 60.633 degrees. In the optical path passing through the laser medium (23),
A predetermined solution is hermetically sealed in a quartz glass container, passes through the second harmonic, and changes from 650 nm to 1100 nm.
A phase conjugate mirror (24) that is highly reflective for a wavelength of nm is provided coaxially with this optical path. Laser medium (2
3), excitation part of laser medium, Brewster dispersion prism
An output mirror (26) forming a phase conjugate mirror (22) and an optical resonator with a laser medium (23) and a Brewster dispersion prism (20) interposed on a laser oscillation optical path (25) determined by (20). Is provided. The laser medium (23) is driven by a driving means in a direction in which the optical path length of transmitted light transmitted through the medium changes. The driving means includes a stage (27) for supporting a laser medium (23), and a driving body (28) for driving the stage (27) in a direction indicated by an arrow C perpendicular to the transmission optical path. The laser medium (23) is shown in FIG.
As shown by the arrow B in (b), it has a C axis in a direction inclined by 10 to 15 degrees with respect to the plane of incidence defined by the Brewster plane, while the polarization plane defined by the Brewster plane is shown in FIG. A direction. In the above configuration, titanium sapphire as the laser medium (23) is a uniaxial crystal and has a different refractive index between the ordinary ray and the extraordinary ray, so that it has polarized light that is neither parallel nor perpendicular to the crystal C axis. When light enters the crystal, it exhibits birefringence. The polarization of the oscillating beam in the optical resonator is in the direction A in the drawing in the laser medium (23) and the Brewster dispersion prism (20), and the laser medium (23) Acts as a wavelength selection element. Driver
According to (28), an arbitrary wavelength can be selected by moving the stage (27) to change the optical path length. It should be noted that the reflection angle may be changed by rotating as shown by an arrow D. In laser oscillation, astigmatism is caused by the laser medium and the Brewster dispersion prism, but the astigmatism is eliminated because one of the optical resonators is a phase conjugate mirror. Was done. As a result, the oscillation beam diameter in the laser medium made of titanium sapphire can be easily controlled by changing the radius of curvature of the output mirror, and the oscillation efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing one embodiment of the present invention. FIG. 2 is a diagram for explaining a laser medium in FIG. 1; FIG. 3 is a configuration diagram showing one of the conventional examples. FIG. 4 is a configuration diagram showing another conventional example. [Explanation of Signs] (20): Brewster dispersion prism, (23): laser medium,
(24)… Phase conjugate mirror, (26)… Output mirror, (27)… Stage, (2
8) ... Driver.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01S 3/00-3/30

Claims (1)

(57) [Claim 1] An excitation light source for outputting an excitation laser beam, a phase conjugate mirror provided in an optical path of the excitation laser beam and transmitting the excitation laser beam, Two surfaces forming an angle are Brewster surfaces, and a dispersion prism type titanium sapphire in which one of the Brewster surfaces and the above-described excitation laser beam incident on this surface are arranged at a Brewster angle. A laser medium composed of a crystal, a Brewster dispersion prism provided with an incident angle of Brewster angle in an optical path transmitted through the laser medium, and the phase conjugate mirror provided in an optical path transmitted through the Brewster dispersion prism. comprising an output mirror constituting an optical resonator, and a driving means for driving in the direction of the optical path length of light transmitted through the laser medium is changed, the laser medium, the Buryusu
10 to 15 degrees with respect to the plane of incidence defined by the plane
Titanium saff having a C-axis in an inclined direction
Fire laser oscillation device.