Reverse-Taper Mid-Infrared Quantum Cascade Lasers for Coherent Power Scaling

Abstract

We present a reverse-taper quantum cascade laser (QCL) emitting at 4.6 µm, a novel-geometry device that can scale the output power while maintaining good beam quality. Buriedridge waveguides with tapered and straight regions were formed by ICP etching and HVPE regrowth -the tapered region scales the output power, while the emitting facet is located at the narrowend taper section, which provides mode filtering by suppressing high-order spatial modes. Beam profiles were observed under quasi-continuous-wave (QCW)/CW operation and beam quality (M 2 ) measurements along with beam-stability measurements were performed -a small degree of collimated-beam centroid movement (<0.46 mrad, peak-to-peak) was observed, along with M 2 values close to 1 up to ∼1 W QCW power. Devices of shorter cavity lengths were also investigated, indicating that the output power scales with the core-region volume but results in a small increase in angular deviation.

Semi-insulating InP:Fe growth by hydride vapor phase epitaxy for advanced buried heterostructure quantum cascade lasers

“…Ohmic contacts are formed on the surface of circular mesas with AuGe/Ni/Au metallization for current-voltage (I-V) characterization, which is used for InP:Fe resistivity calculation. SI-InP regrowth by HVPE was implemented in BH QCL fabrication for double metal waveguide THz micro-pillar array QCL, reverse-tapered high power 4.6 µm QCL 17 and high speed 9.15 µm distributed feedback (DFB) QCL. The performance of fabricated BH QCL devices was characterized systematically.…”