The text has been revised to incorporate new developments in lasers and quantum electronics. Other subjects covered include phase-conjugate optics, long wavelength quaternary semiconductor lasers,The text has been revised to incorporate new developments in lasers and quantum electronics. Other subjects covered include phase-conjugate optics, long wavelength quaternary semiconductor lasers,The text has been revised to incorporate new developments in lasers and quantum electronics. Other subjects covered include phase-conjugate optics, long wavelength quaternary semiconductor lasers,