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 d ispersion cavity with a diffraction grating is coupled to the laser diode t o suppress the subsidiary modes and to tune the central wavelength. A wavel ength-dependent competition between the grating-coupled mode and the intern al Fabry-Perot modes of the laser suggests that a hole burning in the spect ral density of a DWELL laser occurs with a characteristic spectral half wid th of similar to 13 nm (10.5 meV), Simple models of spectral "flattening" a nd spectral hole burning are presented to explain the broad free-running an d grating-coupled lasing spectra of the DWELL device.