DFB Style Slotted Waveguide Interband Cascade Lasers

The first demonstration of single-mode behaviour of interband cascade lasers (ICLs) using a slotted waveguide is presented. Side mode suppression ratios (SMSRs) between 10 – 15 dB are observed for temperatures of 15 – 21.5°C for injection currents near the maximum power output, before the thermal rollover, and after this point. These measurements provide a benchmark for the amount of modulation of the refractive index in the cladding required to interact with the longitudinal cavity modes which is needed to extend the range of conditions of single mode emission. The spectra is observed over different parameters such as number of slots, slot depth, slot spacing, temperature and injection current.