Title :
Low-Loss Surface-Mode Waveguides for Terahertz Si–SiGe Quantum Cascade Lasers
Author :
De Rossi, Alfredo ; Carras, Mathieu ; Paul, Douglas J.
Author_Institution :
Thales Res. & Technol. France, Palaiseau
Abstract :
A new design of low-loss terahertz waveguide for Si-SiGe quantum-cascade lasers (QCLs) is presented. Periodic surface gratings are used to define waveguides without the requirement of cleaved or etched end facets. As Si cleaves along the (111) planes and not in the vertical direction for standard Si (100) substrates, this significantly aids the fabrication of waveguides. Losses down to 2 cm-1 with modal overlap of 0.4 can be achieved for shallow gratings with etched depths of only 0.56 mum for an active material layer thickness of 8 mum. Such low loss and high modal overlap is key to any Si-SiGe QCL being realized
Keywords :
Ge-Si alloys; diffraction gratings; elemental semiconductors; etching; laser modes; optical losses; quantum cascade lasers; silicon; submillimetre wave lasers; waveguide lasers; 0.56 mum; 8 mum; Si; Si (100) substrates; Si cleaving; Si-SiGe; Si-SiGe lasers; etching; laser design; low-loss waveguides; modal overlap; periodic surface gratings; quantum cascade lasers; shallow gratings; surface-mode waveguides; terahertz lasers; Free electron lasers; Optical scattering; Optical surface waves; Optical waveguides; Plasmons; Quantum cascade lasers; Silicon germanium; Surface emitting lasers; Surface waves; Waveguide lasers; Laser; SiGe; silicon; terahertz; waveguide;
Journal_Title :
Quantum Electronics, IEEE Journal of
DOI :
10.1109/JQE.2006.883496
