Coherent light generators – Particular beam control device – Tuning
Reexamination Certificate
2000-04-24
2003-10-28
Ip, Paul (Department: 2828)
Coherent light generators
Particular beam control device
Tuning
C372S021000, C372S022000, C372S023000, C372S028000, C372S070000, C359S330000
Reexamination Certificate
active
06639921
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to solid state lasers. More specifically, the present invention relates to solid state lasers operative in the 8-12 micron range.
2. Description of the Related Art
Lasers are currently widely used for communication, research and development, manufacturing, directed energy and numerous other applications. For many applications, the energy efficiency, power and lightweight of solid state lasers makes these devices particularly useful. Solid state lasers currently lase in the range of one to three microns.
For certain applications, there is a need to reach longer laser operating wavelengths. In particular, there is interest in the 8-12 micron (&mgr;m) region.
Several groups have demonstrated wavelength conversion to this region using various solid-state lasers, or the output from optical parametric oscillators (OPOs) as pump sources for longer wavelength OPOs and difference frequency generation crystals. See for example: 1) S. Chandra, T. H. Allik, G. Catella, R. Utano, J. A. Hutchinson, “Continuously tunable 6-14 &mgr;m silver gallium selenide optical parametric oscillator pumped at 1.57 &mgr;m,” Appl. Phys. Lett. 71, 584-586 (1997); 2)T. Allik, S. Chandra, D. M. Rines, P. G. Schunemann, J. A. Hutchinson, and R. Utano, “7-12 &mgr;m generation using a Cr, Er:YSGG pump laser and CdSe and ZnGeP
2
OPOs,” in
Advanced Solid State Lasers. OSA Trends in Optics and Photonics
(Optical Society of America, Washington. D. C., 1997), Vol. 10, pp. 265-266; and 3) R. Utano and M. J. Ferry, “8-12 &mgr;m generation using difference frequency generation in AgGaSe
2
of a Nd:YAG pumped KTP OPO,” in
Advanced Solid State Lasers, OSA Trends in Optics and Photonics
(Optical Society of America, Washington, D.C., 1997), Vol. 10, pp. 267-269[WJB1].
One approach involved the use of a flashlamp pumped Cr, Er:YSGG laser emitting at 2.79 microns to pump a cadmium selenide (CdSe) OPO. This approach has been represented as being effective to yield a tunable 8-12 micron output. Unfortunately, the poor overall electrical efficiency of the Cr, Er:YSGG pump laser, together with its fairly long (50 ns) output pulse width, result in a less than optimal CdSe OPO pump source.
Hence, a need remains in the art for an efficient, tunable system or method for converting the output of a typical 1-3 &mgr;m laser to the 8-12 &mgr;m range.
SUMMARY OF THE INVENTION
The need in the art is addressed by the solid state laser of the present invention. The inventive laser includes a pump laser for providing an input beam. An optical parametric oscillator (OPO) provides a first stage which shifts the input beam from the first wavelength to a second wavelength. In accordance with the present teachings, a second stage mechanism is included for shifting the beam from a second wavelength to a third wavelength.
In the illustrative embodiment, the mechanism for shifting the beam from the second wavelength to the third wavelength is an OPO using a cadmium selenide crystal. In the illustrative embodiment, the input beam is a one-micron beam and the third wavelength is in the range of 8-12 microns. In the best mode, the first stage OPO includes a crystal which is x-cut potassium titanyl arsenate. A tuning mechanism with an associated controller is provided to tune the OPO as required for a particular application.
The invention provides a novel and efficient system and method for providing an output beam of collimated energy in the 8-12 micron range.
REFERENCES:
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patent: 5400173 (1995-03-01), Komine
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patent: 5841570 (1998-11-01), Velsko
patent: 6344920 (2002-02-01), Fukumoto
Allik et al, Recent advances in continuously tunable 8-12 um radiation using optical parametric oscillators, Spie vol. 3082pp.54-64, 1997.*
Allik T. H. et al., “Advances in Optical Parametric Oscillators with Application to Remote Chemical Sensing”, Institute of Electrical Engineers, Stevenage, GB; XP002180001; and Electro-Optical Technology For Remote Chemical Detection and Identification III, Orlando, Florida, USA, Apr. 13, 1998, vol. 3383, pps. 58-64, Proceedings of the SPIE—The International Society for Optical Engineering, 1998, SPIE-Int. Soc. Opt. Eng., USA, ISSN: 0277-786X.
Komine H. et al: “Tunable Mid-Infrared Wavelength Converters for Neodymium-doped Lasers”, LEOS '94, Conference Proceedings, IEEE Lasers and Electro-Optics Society 1994, 7th Annual Meetings (Cat. No. 94CH3371-2), Proceedings of Leos '94, Boston, MA, USA, Oct. 31-Nov. 3, 1994, pps. 177-178, vol. 2, OP002180004 1994, NY, NY, USA,, IEEE, USA, ISBN: 0-7803-1470-0, p. 177, line 20.
Alkov Leonard A.
Ip Paul
Lenzen, Jr. Glenn H.
Raufer Colin M.
Rodriguez Armando
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