Fig. 1From: InAs/GaAs Quantum Dot Dual-Mode Distributed Feedback Laser Towards Large Tuning Range Continuous-Wave Terahertz ApplicationSchematic diagram and morphology of InAs/GaAs QDs LC-DFB laser structure. a Schematic diagram of InAs/GaAs QD LC-DFB laser structure. Inset: cross-sectional TEM image of the QD active layer structure. b The top view of the SEM image of LC-DFB laser structure with first-order grating. Inset: enlarged SEM image focus on the joint between the grating and ridge waveguideBack to article page