Optical losses and efficiency in GaAs laser diodes

Optical gain and losses of GaAs laser diodes were deduced from the length dependence of the threshold current density and the differential external quantum efficiency at 77 and 300°K. It has been confirmed that the optical gain is proportional to the threshold current density Jt; and the optical losses are given by the sum of current independent termα₀', and current dependent termβ"Jₜ, which is proportional to the threshold current density. The termβ"Jₜdepends on the laser wavelength because the threshold current density depends on the laser wavelength. It is believed thatβ"Jₜis caused by the penetration of the laser oscillations into the noninverted regions surrounding the inverted population region of thep-njunction.