Strained-layer 1.5 mu m wavelength InGaAs/InP multiple quantum well lasers grown by chemical beam epitaxy

A substantial reduction is reported in the threshold current densities for 1.5 mu m wavelength In_xGa_1-xAs/In_xGa_1-xAs_1-yP_y strained-layer multiple quantum well (SL-MQW) lasers over lattice-matched MQW lasers. Threshold current density was found to depend sensitively on the InAs content x and thickness d of the In_xGa_1-xAs quantum wells. Threshold current densities as low as 370 A/cm² and internal quantum efficiency of 90% were obtained for separate confinement heterostructure Sl-MQW lasers having four quantum wells and with x=0.65 and d=5 nm. Such a threshold current density is among the lowest values obtained thus far for 1.5 mu m wavelength InGaAs/InGaAsP MQW lasers. The present lasers were grown by chemical beam epitaxy.