Coherent light generators – Particular resonant cavity – Specified cavity component
Patent
1997-01-03
1998-08-25
Lee, John D.
Coherent light generators
Particular resonant cavity
Specified cavity component
372 19, 372 32, 372 20, H01S 3086
Patent
active
057990328
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laser resonator for at least two laser modes from an optically pumped laser medium.
2. Description of the Related Art
In a laser application, in which some sort of coherent detection is used, there is a need of a stable emitting laser and a local oscillator laser. For detecting Doppler shifts at a satisfactory signal-to-noise ratio, it is also necessary that the difference frequency between the radiation of the emitting laser and that of the local oscillator laser can be kept constant.
Although a laser is considered to be a light source having a minor spread in wavelength, it oscillates in most cases at a plurality of close frequencies at the same time. To make the laser generate radiation at one of these frequencies, use is mostly made of a frequency-discriminating element placed in the resonator. When a solid-state laser is involved, the frequency-discriminating element usually is a Fabry-Perot (F-P) etalon.
A solid-state laser is a laser utilising a solid, such as a crystal, as laser medium. It is optically pumped by using a lamp or another laser, for instance a laser diode. The stability of a solid-state laser designed for single-frequency operation mostly depends on external factors, such as vibrations and variations in temperature and pump intensity.
If you need two or more laser beams having a given difference in oscillation frequency, it is necessary that they be affected in the same manner by external factors. This can be achieved by letting the different oscillators share the same components and surroundings as far as possible. This implies, for instance, that the mirrors included are supported by the same structure and, optionally, that use is made of the same laser medium for the different resonators.
SUMMARY OF THE INVENTION
However, it sill constitutes a problem to hold a constant difference in the oscillation frequency between different laser beams. The basic idea of the invention is to provide the desired constant difference in oscillation frequency between different laser modes by conducting these at different angles through an F-P etalon. The frequency that will oscillate in the resonator is determined by the angle of incidence of each laser mode to the etalon surface. This results in the desired constant difference frequency. When the laser is affected by external factors, these provide the same frequency shift in the different modes, but the frequency difference is kept constant. By changing the angle of the etalon relative to the main axis of the laser, the frequency difference can be adjusted.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail with reference to the accompanying drawings in which
FIGS. 1, 2a, 2b, 3a, 3b, 4, 5a, 5b, 6a, 6b illustrate various embodiments of laser resonators according to the invention,
FIG. 7 shows the geometry of a Fabry-Perot etalon, and
FIG. 8 is a sketch of the angle of incidence of the laser modes to the etalon.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The basic idea of the invention is to provide the desired constant difference in oscillation frequency between different laser modes by conducting these at different angles through an F-P etalon. The frequency that will oscillate in the resonator is determined by the angle of incidence of each laser mode to the etalon surface. This results in the desired constant difference frequency. When the laser is affected by external factors, these provide the same frequency shift in the different modes, but the frequency difference is kept constant. By changing the angle of the etalon relative to the main axis of the laser, the difference frequency can be adjusted.
The geometry of the laser resonator can be arranged in a number of different ways. It is possible to use different shapes of the laser mirrors and the surfaces of the laser medium. It is also possible to arrange an optically refractive element in the resonator between the laser medium and the etalon.
FIG. 1 shows
REFERENCES:
patent: 3482186 (1969-12-01), Chernoch
patent: 3582815 (1971-06-01), Siebert
patent: 3775699 (1973-11-01), Cassels
patent: 4762988 (1988-08-01), Strobel
patent: 4930131 (1990-05-01), Sizer, II
patent: 4930133 (1990-05-01), Babbitt et al.
patent: 5056101 (1991-10-01), Magill et al.
patent: 5151908 (1992-09-01), Huber
patent: 5172383 (1992-12-01), Magill et al.
patent: 5331651 (1994-07-01), Becker et al.
Forsvarets Forskningsanstalt
Lee John D.
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