Enhanced relaxation oscillation frequency and reduced nonlinear K-factor in InGaAs/InGaAsP MQW lambda /4-shifted DFB lasers

The relaxation oscillation frequency, fr, of 1.55 μm InGaAs/InGaAsP MQW λ/4-shifted DFB lasers was doubled by increasing the carrier injection efficiency into each quantum well, which results from an optimised bandgap energy and optimised thickness of the barrier layers. The nonlinear K-factor which determines the maximum modulation band-width through the damping phenomenon can be reduced by dopting a p-type modulation doped MQW structure in the active layer.