Theoretical comparison of 0.78% tensile strained InGaAs/InAlGaAs and InGaAs/InGaAsP quantum-well lasers emitting at 1.55 μm

Abstract

0.78% tensile strained InGaAs/InAlGaAs and InGaAs/InGaAsP QW lasers emitting at 1.55 μm are studied theoretically. Independent of material system, large band discontinuity (large barrier band gap) results in a large number of subbands and high density of states, which gives rise to lower optical gain and T0. Besides, the 3 dB bandwidth is increased and is more resilient to high temperature. InGaAs/InAlGaAs QW lasers (0.78% strained, barrier band gap = 1.12 eV) can achieve threshold of 572 Acm-2, T0 of 45K and 3 dB bandwidth of 38 GHz at gain of 100 cm-1. InGaAs/InGaAsP QW lasers (0.78% strained, barrier band gap = 1.2 eV) can only achieve 22 GHz. This suggests that the low conduction band offset ratio limits the bandwidth of InGaAs/InGaAsP QW lasers. InGaAs/InAlGaAs laser, on the other hand, could be designed to give low threshold, large bandwidth and high T0.