Broad area single mode operation of quantum cascade lasers by integrating porous waveguide and distributed feedback grating

摘要

Quantum cascade laser (QCL) emitting at 4.8 μm with a single-longitudinal mode and small divergence was achieved by integrating porous (PS) waveguide structure and distributed feedback (DFB) grating. The PS waveguide is fabricated in highly doped InP cladding layer by electro-chemical etching process. The DFB grating was defined above the active region by holographic lithography technique. A fundamental transverse mode of single-lobed radiation far-field pattern with full width at half maximum of 7.8° was obtained. Single-longitudinal mode emission with a high peak power of 1.2 W was achieved. Our work is useful for many potential applications of the QCL.