High-frequency characteristics of directly modulated InGaAsP ridge waveguide and buried heterostructure lasers

The high-frequency modulation characteristics of InGaAsP ridge waveguide lasers at 1.55 μm and etched mesa buried heterostructure (EMBH) lasers at 1.3 μm are investigated. Small-signal and large-signal circuit models are developed for both devices, and the main factors which influence the high-frequency modulation response are established. It is shown that the electrical parasitics in the chip dominate the small-signal frequency response of the EMBH laser and limit the large-signal turn-on and turn-off times. The small-signal and large-signal responses of both devices show strong damping of the relaxation oscillations. This damping can be modeled accurately using field-dependent optical gain compression in the rate equations.