INDEX-COUPLED DISTRIBUTED-FEEDBACK SEMICONDUCTOR QUANTUM CASCADE LASERS FABRICATED WITHOUT EPITAXIAL REGROWTH

摘要

Quantum cascade (QC) lasers and methods of fabricating such QC lasers are provided. The QC lasers incorporate a DFB grating without requiring the use of relying on epitaxial regrowth processes. The DFB gratings are formed as sidewall gratings along the lateral length of the QC active region, or the DFB gratings are formed atop the lateral length of the QC active region, and wherein the top DFB grating is planarized with a polymeric material.

主权项

1. A quantum cascade laser comprising:
an elongated waveguide ridge having characteristic width and length dimensions and being formed of a plurality of epitaxial layers, the longitudinal dimension of the waveguide ridge defining a laser cavity comprising an active region of semiconductor quantum well structures configured to employ intersubband electronic transitions; at least one conductive epitaxial cladding layer disposed atop and below the active region of the waveguide ridge; a distributed feedback grating comprising a plurality of periodic vertical corrugations formed into both lateral edges of the waveguide ridge along the longitudinal length of said waveguide ridge, the corrugations having characteristic modulation depth and pitch; a dielectric layer conformally disposed atop the distributed feedback grating; a conductive contact layer disposed atop the dielectric layer and elongated waveguide ridge; wherein the corrugations are disposed through at least the top cladding layer and each of the epitaxial layers of the waveguide ridge; and wherein the width of the waveguide ridge and the modulation depth and pitch of the corrugations are configured such that the corrugations have a coupling coefficient sufficient to interact with the active region of the laser to impose single-mode emission at specific engineered wavelengths thereon.