Coherent light generators – Particular active media – Semiconductor
Patent
1995-10-28
1997-11-11
Davie, James W.
Coherent light generators
Particular active media
Semiconductor
313463, 313474, 372 74, H02S 319, H02J 2910
Patent
active
056871856
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCES TO RELATED APPLICATIONS
This application is related to Applicant's Russian application Serial No. 92014713/21, filed Dec. 28, 1992 and International application Serial No. PCT/RU/00318, filed Dec. 27, 1993 on which Applicants claim foreign priority under 35 U.S.C..sctn..sctn.119 and 365.
FIELD OF THE INVENTION
The invention belongs to the field of quantum electronics and electronic engineering and may be used in devices where a scanning light beam is used, more particularly in television projector systems.
BACKGROUND OF THE INVENTION
A prior art laser cathode-ray tube being in fact a scanning semiconductor laser with longitudinal pumping by an electron beam comprises a source of an electron beam and a means for its control, and also a laser target which is a semiconductor member with mirror coverings, which forms an optical resonator. The laser target is glued to a heat removing substrate which is transparent to a generated laser beam (A.S.Nasibov. "Laser cathode-ray tube--new device of the quantum electronics".--Bulletin of the Academy of Sciences of the USSR, No.9, pp.48-56). The electron beam penetrates through one of mirrors into semiconductor member, excites some region of this member wherein it causes nonequilibrium current carriers--electron-hole pairs, which recombine with emitting light. The optical gain aroused in this excited region and optical resonator generates the laser beam. The laser beam is generated from a spot on the laser target where the focused electron beam to be located. The laser beam scanning and modulation of its intensity are made by scanning of the electron beam and changing its current.
The main disadvantage of this device is that high efficiency and long lifespan of the laser target can only be achieved simultaneously only at cryogenic temperature. The reason is due the to level of excitation of semiconductor member with electron beam pumping is very non-uniform over the volume of the member. Thus, if a semiconductor member is used which has a thickness of more than the average depth of the electron beam excitation of the target, there are parts of the member which are little-excited or not excited at all. These parts, however, absorb light emanating from the high-excited parts. This is especially true when the member is at temperatures higher than cryogenic temperatures. This decreases laser efficiency and the lifespan of the member. If a thinner semiconductor member is used the laser efficiency may be high enough and in some cases electrons can to penetrate through the member and partly transparent mirror covering into glue layer and destroy it, making the lifespan small.
Another kind of prior art laser cathode-ray tube has a laser target made of a semiconductor with a two-layer structure (A. A. Matyash et al, "Semiconductor laser with longitudinal electron pumping", USSR Patent No.1034569, issued Nov. 2, 1981 and described in a paper by V. N. Katsap et al., "Heterostructures CdS.sub.x Se.sub.l-x /CdS in Lasers with Longitudinal Pumping by Electron Beam", Sov. J. of Quantum Electronics, 1997, Vol.14, pp.1994-1997). The layer of CdS.sub.x Se.sub.l-x with narrower bandgap is pumped by an electron beam and its thickness is approximately equal to the typical depth of penetration of an electron beam into a laser target. The wider bandgap layer of CdS has thickness several times larger and performs two functions: on one hand, it separates partly transparent mirror covering and glue layer from the zone of electron beam pumping, and therefore increases the lifespan of laser target, on the other hand, this layer having wider bandgap does not absorb generated emission and allows, therefore, an increase in the operating temperature of the laser target. The problem is that it is very difficult to make this device with an adequate efficiency because centers of non-emitting recombination are formed near the interface boundary (heteroboundary) between two relatively thick semiconductor layers made of II-VI compounds and laser efficiency is rather low (3% at 300 K.
REFERENCES:
patent: 3558956 (1971-01-01), Basov et al.
patent: 3864645 (1975-02-01), Packard et al.
patent: 3982207 (1976-09-01), Dingle et al.
patent: 4539687 (1985-09-01), Gordon et al.
patent: 4695332 (1987-09-01), Gordon et al.
patent: 4866489 (1989-09-01), Yokogawa
patent: 5181218 (1993-01-01), Ishikawa et al.
patent: 5374870 (1994-12-01), Akhekyan et al.
"Electron beam pumped lasing in ZnSe/ZnSSe superlattice structures grown by molecular-beam epitaxy" by D.A. Cammack, R.J. Dalby and J. Khurgin of Applied Physics vol. 62, No. 7, 1 Oct.,87, Woodbury, US.
"Blue Solid State Laser Based On Electron-Beam Pumped ZnSe/ZnSSe Double Heterostructures" by H.J. Cornelissen, C.J. Savert and J.M. Gaines, Philips Journal of Research vol. 46 Nos 4-5 1992, Philips Research Laboratories, The Netherlands.
Kozlovsky Vladimir I.
Lavrushin Boris M.
Davie James W.
Principia Optics, Inc.
Principia, Optics, Ltd.
Sicotte John F.
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