Broad continuous frequency tuning of a diode laser with an external cavity

Abstract

A broad continuous frequency tuning of a double-heterostructure AlGaAs GaAs diode laser with a short dispersive external cavity has been examined both theoretically and experimentally. The external cavity has been composed by a micro lens and a Littrow diffraction grating placed 10-mm apart from a non-perfectly AR-coated front facet of the laser chip. The frequency tuning has been accomplished by simultaneously varying 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 111 000 GHz/s has been obtained.