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.