Fig. 4From: Stable Single-Mode Operation of Distributed Feedback Quantum Cascade Laser by Optimized Reflectivity Facet Coatingsa, b Output power versus current of the DFB laser operated in CW mode at different heat sink temperatures between 20 and 90 °C along with V-I curves. c, d CW lasing spectra at different currents from 150 to 250 mA with a step of 25 mA at 20 °CBack to article page