Properties of GaInNAsSb narrow ridge waveguide laser diodes in continuous-wave operation at 155um

The room-temperature 1.55 m m continuous-wave (CW) operation of single-lateral mode GaInNAsSb ridge waveguide lasers grown on GaAs is reported. Detailed measurements of the light output power and spectral properties were used to assess the device characteristics as a function of applied current and temperature in both CW and pulsed operation. An exemplary, 3 m ×750 m m, device with a 92% high-reflectivity back facet coating exhibited a record low CW threshold current of 63~mA, with a peak output power of 15~mW. High-resolution modal gain spectra were extracted from amplified spontaneous emission measurements yielding the internal loss (8.0~cm -1 , transparency current (50~mA) and the wavelength dependence of the differential gain. The latter was used with careful measurements of the Fabry-Perot mode shift with injection current to determine the linewidth enhancement factor of 2.8 at the transparency current. The first measurement of intrinsic modulation frequency in 1.55 m m GaInNAsSb lasers is reported, based on the observed relative intensity noise (RIN). The RIN measurements indicate a maximum modulation frequency of 7.2~GHz, which is a promising result for future telecommunications applications.