Directional emission, increased free spectral range and mode Q-factors in 2-D wavelength-scale optical microcavity structures

Boriskina, Svetlana V.; Benson, Trevor M.; Sewell, Phillip; Nosich, Alexander I.

Directional emission, increased free spectral range and mode Q-factors in 2-D wavelength-scale optical microcavity structures

Authors

Boriskina, Svetlana V.

Benson, Trevor M.

Sewell, Phillip

Nosich, Alexander I.

Description

Achieving single-mode operation and highly directional (preferably unidirectional) in-plane light output from whispering-gallery (WG) mode semiconductor microdisk resonators without seriously degrading the mode Q-factor challenges designers of low-threshold microlasers. To address this problem, basic design rules to tune the spectral and emission characteristics of micro-scale optical cavity structures with nanoscale features by tailoring their geometry are formulated and discussed in this paper. The validity and usefulness of these rules is demonstrated by reviewing a number of previously studied cavity shapes with global and local deformations. The rules provide leads to novel improved WG-mode cavity designs, two of which are presented: a cross-shaped photonic molecule with introduced asymmetry and a photonic-crystal-assisted microdisk resonator. Both these designs yield degenerate mode splitting, as well as Q-factor enhancement and directional light output of one of the split modes.
8 pages with 13 figures (to appear in the Special Issue of JSTQE on Nanophotonics, 2006)