BROAD CONTINUOUS FREQUENCY TUNING OF A DIODE-LASER WITH AN EXTERNAL-CAVITY

A broad continuous frequency tuning of a double-heterostructure AlGaAs /GaAs diode laser with a short dispersive external cavity has been exa mined both theoretically and experimentally. The external cavity has b een composed by a micro lens and a Littrow diffraction grating placed IO-mm apart from a non-perfectly AR-coated front facet of the laser ch ip. The frequency tuning has been accomplished by simultaneously varyi ng the optical lengths of the internal and external laser cavities due to an opto-electrical feedback. Continuous frequency tuning over 200 GHz near 850-nm wavelength with a sweep rate of 111000 GHz/s has been obtained.