Optical loss suppression in long-wavelength semiconductor lasers at elevated temperatures by high doping of the n-waveguide
We show that strong n-doping of the n-waveguide layer substantially decreases the thermal carrier leakage from the active layer and the associated optical losses in III–V semiconductor lasers. The effect is particularly pronounced in devices operating at the wavelength region where the free hole absorption cross-section is much greater than that of free electrons. This is predicted to decrease the threshold current and improve the output efficiency of the lasers. An example of a bulk InGaAsP/InP pulsed lasers is used to demonstrate that lasers with highly doped n-InGaAsP side of the waveguide can retain high output powers at ambient temperatures substantially above room temperature.