Ridge-width dependence of midinfrared interband cascade laser characteristics

Abstract

We report an experimental study of how the light-current characteristics and lateral mode properties of interband cascade lasers depend on ridge width. Narrower ridges provide greater heat dissipation due to lateral flow, along with operation in a single lateral mode. However,sidewall imperfections increase the cw threshold current density somewhat, from Jth = 582 A/cm2 at 300 K for an 11-µm-wide ridge to 713 A/cm2 and 1.07 kA/cm2 for 5- and 3-µm-wide ridges, respectively. The narrowest ridges similarly display a degradation of the slope efficiency. A 13-µm- wide ridge produced 45 mW per facet of cw output power and maximum wall-plug efficiency of 3.5% per facet at T = 20°C. A 5-µm-wide ridge with 3-mm cavity length and no facet coatings operated cw at = 3.5-µm to a new record temperature of 345 K for the 3 to 4-µm spectral range.