Reduced free carrier absorption loss in midinfrared double heterostructure diode lasers grown by liquid phase epitaxy

摘要

An improved InAsSb/InAsSbP double heterojunction ridge laser was designed and grown by liquid phase epitaxy. The cladding layer absorption loss was minimized by the introduction of two undoped quaternary layers on either side of the active region to form a five layer epitaxial structure. The inserted layers also helped alleviate interdiffusion of unwanted dopants into the active region and reduced current leakage in the device. The resulting diode lasers operate readily in pulsed mode near 3.5 μm at elevated temperatures and with a threshold current density as low as 118 A cm~(-2) at 85 K. Compared to the conventional three-layer double heterostructure laser, the modified structure with reduced optical loss increased the maximum lasing temperature by 95-210 K.