WAVELENGTH TUNABLE SINGLE-MODE LASER-DIODES

Wavelength tunable single mode InGaAsP semiconductor lasers in the 1.5 mum wavelength range are key devices in coherent optical communication systems and in advanced sensing applications. The physical principles of continuously tunable single mode laser diodes are discussed and corresponding device structures are presented together with their relevant lasing characteristics. Particular emphasis is put on the recently developed tunable twin-guide (TTG) laser, that offers an inherent continuous tuning behaviour and a convenient device control. The basic relationship between electronic wavelength tuning and spectral linewidth broadening is derived and rules for an optimized laser design are discussed.