FREE EXCITON INDIRECT TRANSITION LASER MATERIAL AND APPARATUS

摘要

1,267,374. Lasers. MINNESOTA MINING & MFG. CO. 21 March, 1969 [25 March, 1968; 3 March, 1969], No.. 15065/69. Heading HlC. A room temperature semi-conductor laser, Fig. 5, comprises a crystalline compound which. is cut or. cleaved to form. opposed major faces 104, 106 which define the resonator, the semiconductor being end. pumped. by an. electron beam. 114 or by optical methods and being chosen for use by comparison. of its. reflection and spontaneous emission spectra at. 77‹ K. The semi-conductor crystal 100 is mounted on a sapphire support 102, and its end faces may be silvered to. about 90% reflectivity, the stimulated emission passing through the support at 116. The semi-conductor is of a direct band gap kind, that is the.minimum energy in the conduction band lies at substantially the same position in the Brillouin zone as the maximum energy in the valence band, is chosen by comparison of its side pumped reflection and spontaneous . emission spectra at 77‹ K., Figs. 7-14 (not shown), suitable materials for use at room temperature including theoxides; sulphides, telurides or selenides of zinc or cadmium. A xenon lamp or a further laser may also be used to pump the semi-conductor; and a theoretical derivation of the minimum pumping energy required is given.