Index-Coupled Quantum-Dot 1.3- $\mu$ m Distributed-Feedback Lasers Fabricated With a Combination MOCVD/MBE Process

Quantum-dot (QD) lasers have been widely studied due to their attractive features of low-threshold current density, high gain, low chirp, and superior over-temperature performance. In this letter, index-coupled 1.3- μm distributed-feedback (DFB) lasers were fabricated using wafer-level interference lithography for grating patterning, molecular beam epitaxy for QD growth, and metal-organic chemical vapor deposition for grating overgrowth. Single-mode, ridge waveguide devices with various cavity lengths were antireflection (AR)/ high-reflection (HR) coated and tested. Typical DC characteristics of 1500- μm devices at room temperature were threshold currents of ~50 mA, slope efficiency of ~0.25 W/A, and SMSRs >; 40 dB. Demonstration of a feasible process for wafer level fabrication along with elimination of the deleterious effects of the metal surface grating, may allow these devices to make commercial inroads.