Coherent light generators – Particular beam control device – Having particular beam control circuit component
Patent
1989-08-25
1992-04-21
Epps, Georgia Y.
Coherent light generators
Particular beam control device
Having particular beam control circuit component
372 32, H01S 310
Patent
active
051075113
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a method of stabilizing laser wavelength and a laser device with stabilized wavelength.
BACKGROUND OF THE INVENTION
FIG. 1 is a structural view showing a conventional narrow bandwidth laser shown, for example, in a magazine called "CAN. J. PHYS. VOL 63 ('85) 214".
This FIG. shows a laser medium 1, a full reflection mirror 2, an incomplete reflection mirror 3, an etalon 4 for rough tuning, an etalon 5 for fine tuning and a laser beam 6.
A brief description of the operation of this laser follows. In FIG. 1 laser medium 1 is surrounded by a light resonator consisting of the full reflection mirror 2 and the incomplete reflection mirror 3, whereby light is amplified while being reflected within the light resonator numerous times before exiting as laser beam 6. Some laser resonators found in, for example, excimer lasers, semiconductor lasers, pigment lasers and some types of solid-state lasers, have large oscillating wavelengths. By inserting spectroscopy elements into the light resonator, their oscillating wavelength width can be narrowed. For example, a laser beam extremely close to monocolor can be obtained by using a plurality of Fabry-Perot etalons (hereinafter to be abbreviated as etalon).
In the example of FIG. 1, two etalons, that is, the etalon 4 for rough tuning and the etalon 5 for fine tuning are inserted into the light resonator. FIG. 2 shows various wavelength profiles describing the principle behind the narrowing of the oscillation width of the laser. FIG. 2(a) shows a spectroscopy characteristic of the etalon for rough tuning. The peak position .lambda.m.sub.1 of the spectroscopy characteristic is represented by the following equation (1), ##EQU1##
Here, n is the index of refraction of a material existing between two mirrors forming the etalon, d is a distance between the mirrors, .theta..sub.1 is an angle when light is incident upon the etalon, and m is an integer. Peaks correspond to the different of value of m. As is clear from equation (1), peak wavelength of the mountain can be changed arbitrarily by changing the value of any of n, d, and .theta.. The distance between peaks is called free spectral range (hereinafter to be abbreviated as FSR), and is represented by the following equation (2). ##EQU2## The half band width .DELTA..lambda., of each peak is represented by the following equation (3). ##EQU3## Here F.sub.1 is called finesse and is determined by the performance characteristics of the etalon.
FIG. 2(c) shows the spectroscopy characteristic of the gain of a laser medium. When spectroscopy elements do not exist in the light resonator to narrow the wavelength of the light, light is amplified to become a laser beam over the entire wavelength in the range of the gain. FIG. 2(a) illustrates the state where loss is minimized at only the position of .lambda..sub.0 due to the existence of the etalon for rough tuning. Therefore light is amplified and oscillated at only the vicinity of this wavelength, by deciding d.sub.1 and the like so that the peak position .lambda.m.sub.1 of the talon for rough tuning is equal to any wavelength .lambda..sub.0 in the range where gain exists, and the peaks other than .lambda.m.sub.1 do not come into the wavelength where gain exists.
The minimum value of FSR.sub.1 is determined when there is only one peak and finesse F is determined by the performance characteristics of the etalon. Since the finesse value is about 20, there is a limit to wavelength width which can be narrowed only by one etalon for rough tuning.
According to the present invention, another etalon for fine tuning 5 is used. A spectroscopy characteristic of the fine tuning etalon, for example, is illustrated in FIG. 2(b). Therein, the peak wavelength .lambda.m.sub.2 should be .lambda..sub.0 and FSR.sub.2 should be FSR.sub.2 .gtoreq..DELTA..lambda..sub.1. When the wavelength to be amplified and oscillated is desired to be narrower, another etalon can be used.
According to the invention, the laser beam, whose spectroscopy characteristic was, for
REFERENCES:
patent: 3546622 (1970-12-01), Peterson et al.
patent: 3628173 (1971-12-01), Danielmeyer
patent: 3676799 (1972-07-01), Danielmeyer
patent: 3967211 (1976-06-01), Itzkan
patent: 4150342 (1979-04-01), Johnson, Jr. et al.
patent: 4914662 (1990-04-01), Nakatani et al.
patent: 4947398 (1990-08-01), Yasuda et al.
patent: 4977563 (1990-12-01), Nakatani et al.
Haruta Kenyu
Kaneko Hiromi
Minowa Yoshibumi
Mukumoto Hiroyuki
Nagai Haruhiko
Epps Georgia Y.
Mitsubishi Denki & Kabushiki Kaisha
LandOfFree
Method of stabilizing laser wavelength and laser device with sta does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of stabilizing laser wavelength and laser device with sta, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of stabilizing laser wavelength and laser device with sta will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1593695