We proposed a sensitive gas sensor based on one dimensional photonic crystal (1D-PC) cavity in terahertz frequency range. The cavity Consists of stacks of high-resistivity silicon layers and air spacers, and has a very high quality factor exceeding 1200. The defect modes are very sensitive to the small change of the refractive index of materials in the cavity. The resonant mode shifts about 34MHz when the air in cavity is replace by CO2. Such shift of frequency is attributed to the refractive index change of air in the cavity. The frequency shifts for different ratio mixture of air and CO2 are also measured. Thus, the cavity can be used to measure components ratio of mixed gas.

Date Published: 13 March 2012
PDF: 5 pages
Proc. SPIE 8330, Photonics and Optoelectronics Meetings (POEM) 2011: Laser and Terahertz Science and Technology, 833011 (13 March 2012); doi: 10.1117/12.919002

Published in SPIE Proceedings Vol. 8330:
Photonics and Optoelectronics Meetings (POEM) 2011: Laser and Terahertz Science and Technology
Jianquan Yao; X. C. Zhang; Dapeng Yan; Jinsong Liu, Editor(s)