Tunable grating-coupled laser oscillation and spectral hole burning in an InAs quantum-dot laser diode

Emission spectra are investigated of a low-threshold InAs quantum-dot laser of the "dots-in-a-well" (DWELL) type operating near 1230 nm. An external dispersion cavity with a diffraction grating is coupled to the laser diode to suppress the subsidiary modes and to tune the central wavelength. A wavelength-dependent competition between the grating-coupled mode and the internal Fabry-Perot modes of the laser suggests that a hole burning in the spectral density of a DWELL laser occurs with a characteristic spectral half width of /spl sim/13 nm (10.5 meV). Simple models of spectral "flattening" and spectral hole burning are presented to explain the broad free-running and grating-coupled lasing spectra of the DWELL device.