Ultra-high-speed strain-compensated MQW lasers with reduced carrier transport effect and enhanced differential gain

We theoretically investigated the optimum design of high-speed multiple-quantum-well (MQW) lasers operating at 1.55-μm, and experimentally demonstrated a wide-bandwidth of 30 GHz from a strain-compensated InGaAlAs/InGaAsP MQW laser with 20 wells at a cavity length of 120 μm In our calculations, various combinations of well and barrier materials are examined for lattice-matched, strained-layered, and strain-compensated (SC) MQW lasers with InGaAsP and InGaAlAs barriers. The bandgap wavelength for the barrier layers was varied from 1.1 to 1.3 μm It was possible to eliminate the carrier transport effect and simultaneously achieve a large differential gain by using the InGaAlAs barrier layers for SC-MQW lasers. Experimental results showed a steady increase in the maximum relaxation oscillation frequency when the number of wells was increased from 10 to 20 and the cavity length was reduced from 350 to 120 μm