Open AccessControlled excitation of higher radial order whispering gallery modes with metallic diffraction grating
Author(s) -
Yanyan Zhou,
Feng Luan,
Bobo Gu,
Xin Yu
Publication year - 2015
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.23.004991
Subject(s) - whispering gallery wave , optics , diffraction , grating , diffraction grating , materials science , excitation , phase (matter) , laser , physics , quantum mechanics
Metallic diffraction grating coupler is investigated for controlled excitation of whispering gallery modes (WGMs) of different radial orders. Based on effective mode index calculations and finite difference time domain method, it is found that higher radial order WGMs can be separated from the fundamental modes by sending them into the opposite propagation direction. By phase-matching designs, the metallic diffraction grating provides extra freedom to switch propagation directions, and is able to selectively enhance or suppress different radial-order WGMs. Such structure offers a simple and practical configuration for various WGM applications including liquid sensing, band pass filtering and fiber lasers.