The analysis of the variation of the threshold current with pressure in semiconductor quantum well lasers

Since the loss mechanisms in a semiconductor laser are often strongly wavelength dependent and hydrostatic pressure can vary the bandgap, the pressure dependence of the threshold current can then provide a clear picture of the dominant loss mechanisms in a given laser structure. The pressure dependence of the optical confinement factor, band structure, transparency and threshold carrier density and the combined effect of these on both radiative and non-radiative current contributions have been evaluated for lasers operating at a range of wavelengths using basic equations which makes our analysis particularly attractive owing to its simplicity and ability to predict the main effects involved. We investigate in particular the predicted pressure dependence of several Auger processes in long-wavelength (1.55 µm) lasers. It is found that the rate of decrease of phonon-assisted Auger recombination with pressure is close to that observed experimentally, implying that phonon-assisted Auger is the dominant loss mechanism.