We demonstrate an ultra-narrow-band mode-selection method based on a hybrid-microsphere-cavity which consists of a coated silica microsphere. Optical field distribution and narrow-band transmission spectrum of the whispering gallery modes (WGM) are investigated by finite-difference time-domain method. WGM transmission spectra are measured for microsphere and tapered fibers with different diameters. A high refractive index layer coated on the microsphere-cavity make the Q factor increased, the transmission spectrum bandwidth compressed and the side-mode suppression ratio increased. Parameters of the hybrid-microsphere-cavity, namely, the coated shell thickness and its refractive index are optimized under different excitation light source as to investigate the whispering-gallery-modes’ transmission spectrum. The 3dB bandwidth of the proposed filter can be less than MHz which will have great potential for applications in all-optical sensing and communication systems.

Date Published: 19 October 2016
PDF: 5 pages
Proc. SPIE 10153, Advanced Laser Manufacturing Technology, 1015311 (19 October 2016); doi: 10.1117/12.2247002

Published in SPIE Proceedings Vol. 10153:
Advanced Laser Manufacturing Technology
Bingheng Lu; Huaming Wang, Editor(s)