Abstract

The dynamics of a surface-emitting laser (SEL) with cw optical injection are studied. The molecular-beam-epitaxy grown SEL has an active region consisting of 0.72-μm bulk GaAs and two high-reflectivity mirrors with 22 and 27 periods of 62.5-nm AlGaAs (x = 0.143)/73.3-nm AlAs, respectively. Lasing occurs in a single longitudinal and transverse mode at 886 nm when pumped by an 830-nm edge-emitting diode laser. A tunable dye laser generates the injection signal. At a detuning of 3 GHz, the lasing frequency is pulled toward the injection until complete locking is achieved at an injection level of 5 μW. Asymmetric relaxation-oscillation side-bands spaced about 6 GHz from the injection frequency are observed at higher injection powers, the low-frequency band being stronger. When the injected power is increased further to 0.2 mW, a new lower-frequency sideband appears and is pushed away by as much as 30 GHz as the injection power is increased to 5 mW. Preliminary calculations show that the observed complex phenomena can only be understood by including both the gain saturation and nonlinear index change in the theoretical modelling.

© 1992 Optical Society of America