A red-shift in the diode modes with increasing optical feedback is observed in external-cavity AlxGa1−xAs injection lasers. This shift is due to a change in the refractive index in the active region resulting from a reduction in the population-inversion induced by the optical feedback. This leads to a new determination of the carrier dependence of the refractive index at the laser wavelength in the active region of semiconductor lasers independent of current-induced thermal effects.

We report the generation of extremely short pulses using a superluminescent diode with a monolithically integrated absorber in an external cavity coupled to an additional empty cavity. The pulses obtained have an autocorrelation width of 1.8–2.6 ps without pulse compression. After pulse compression external to the coupled cavity, the pulse width is further reduced to as short as approximately 190 fs. The short pulses are obtained by careful adjustment of the length of the auxiliary cavity to match that of the main cavity.

No abstract

The relationship between the modulation frequency and maximum modulation depth for stable and low-noise oscillation in external-cavity semiconductor lasers is investigated. Sharp resonances in the threshold for the onset of instability occur when the laser is nearly synchronously modulated. A physical model is proposed to explain these observations.

Colliding pulse mode locking of a semiconductor laser is achieved by monolithically integrating an absorber in the center of a laser diode structure with chemically assisted ion beam etched angled facets in an external ring cavity. Minimum deconvolved pulses as short as 1.6 ps before compression and near-transform-limited pulses of 0.35 ps after compression are measured.