Coherent light generators – Particular beam control device – Nonlinear device
Utility Patent
1998-07-17
2001-01-02
Font, Frank G. (Department: 2877)
Coherent light generators
Particular beam control device
Nonlinear device
C372S022000
Utility Patent
active
06169755
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a laser-diode-pumped solid state laser and an optical system using the same.
There has been known a laser-diode-pumped solid state laser in which a solid laser crystal is axially excited by a laser beam emitted from a laser-diode, and an infrared laser beam is oscillated by an resonator constructed in an axial direction.
Such laser-diode-pumped solid state laser is compact in size, has a long useful life, capable of oscillating with a single longitudinal mode, and can perform a high frequency modulation.
Usually, a laser-diode for producing a laser beam has an output of 100 mW or more to produce a laser beam having a wavelength of 808-810 nm, which is absorbable by a solid laser crystal. On the other hand, a solid laser crystal is a YAG (Yttrium Aluminium Garnet) containing a certain amount of rear earth element such as Nd (Neodymium).
In practice, with a laser-diode-pumped solid state laser, it is required that a laser beam emitted from a laser-diode be absorbed by a solid laser crystal with a high efficiency.
A laser-diode capable of giving a highest output can produce a laser beam having a wavelength of 800 nm. Since Nd
3+
(Neodymium) can absorb a light having a wavelength near 800 nm, an oxide crystal containing Nd has been widely used to serve as a solid laser crystal.
However, in order to use a single longitudinal mode to effect an oscillation so as to obtain a laser beam having a stabilized oscillation frequency and containing only a low noise, it is required that a frequency interval (between every two resonator modes) be large, thus requiring a solid laser crystal to be made with a small thickness.
On the other hand, if a solid laser crystal is made to have only a small thickness, a light amount passing through the solid laser crystal will be increased, resulting in a problem that only a small amount of light can be absorbed by the solid laser crystal. As a result, it is impossible to effectively obtain an infrared laser beam from the beams emitted from the laser-diode.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved laser-diode-pumped solid state laser and an optical system using the same, which is capable of effectively absorbing a laser beam emitted from a laser-diode, and producing an infrared laser beam with a high efficiency, so as to solve the above-mentioned problems peculiar to the above-mentioned prior arts.
According to the present invention, there is provided a laser-diode-pumped solid state laser, comprising: a solid laser medium; a laser-diode capable of producing a laser beam for exciting the solid laser medium; a pair of mirrors which forms a resonator for resonating a light excited by the solid laser medium. In particular, an interval between the pair of mirrors is determined such that a gain width GW of the solid laser medium and a frequency interval FS (between every two resonator modes) satisfies an equation 0.1≦FS/GW<1.
In one aspect of the invention, the pair of mirrors are formed by a pair of mutually facing reflective films disposed on both sides of the solid laser medium.
In another aspect of the invention, the solid laser medium is either YVO
4
crystal (yttrium vanadium oxide) containing Nd, or YAG crystal (Yttrium Aluminium Garnet) containing Nd.
In further aspect of the invention, the solid laser medium, the laser-diode and the pair of mirrors are mounted on an identical thermally conductive support means. Further, a temperature control device is provided for controlling the temperature of the thermally conductive support means.
In a still further aspect of the invention, the solid laser medium, the laser-diode and the pair of mirrors are enclosed within a case having a window formed on one side thereof, which side emitting a light beam excited by the solid laser medium. In addition, the case has polarization elements or wavelength plates provided adjacent to said window.
According to the present invention, there is also provided an optical system, comprising: a first laser light source and a second laser light source, capable of producing laser beams having mutually orthogonal polarization planes; a beam splitter capable of synthesizing together the laser beams emitted from the first and second laser light sources; an optical means for converging a synthesized laser beam from the beam splitter and directing the same to an optical fiber. In particular, each of the first and second laser light sources is a laser-diode excitable solid laser, which includes a solid laser medium; a laser-diode capable of producing a laser beam for exciting the solid laser medium; a pair of mirrors which forms a resonator for resonating a light excited by the solid laser medium. Further, an interval between the pair of mirrors is determined such that a gain width GW of the solid laser medium and a frequency interval FS (between every two resonator modes) satisfies an equation 0.1≦FS/GW<1. Moreover, a distance between the beam waist of a laser beam of the first laser light source and the beam splitter before the laser beam is incident on the converging lens, is equal to a distance between the beam waist of a laser beam of the second laser light source and the beam splitter before the laser beam is incident on the converging lens.
The above objects and features of the present invention will become better understood from the following description with reference to the accompanying drawings.
REFERENCES:
patent: 5197073 (1993-03-01), Oka
patent: 5978392 (1999-11-01), Adachi
Mochizuki Manabu
Murakami Yutaka
Arent Fox Kintner & Plotkin & Kahn, PLLC
Font Frank G.
Pioneer Electronic Corporation
Rodriguez Armando
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