We have recently developed a refractive index (RI) sensor using a band-pass filter (BPF) composed of dielectric multilayer films deposited on an optical fiber end. An optical spectrum analyzer was, however, conventionally employed in this sensor to obtain the reflection wavelength, which limited the total measurement speed due to its second-order sweep time. In this study, we enhance its measurement speed by use of a high-speed demodulator where the optical wavelength information is converted into electrical voltage using the linear slopes of the reflection spectra. The response time of the sensor, which is influenced by the dynamic behavior of the sample liquid, is found to be as short as several tens of micro-seconds. We also compare its RI sensitivity with that of a simple Fresnel-based RI sensor.

Date Published: 17 October 2012
PDF: 4 pages
Proc. SPIE 8421, OFS2012 22nd International Conference on Optical Fiber Sensors, 84211V (17 October 2012); doi: 10.1117/12.974464

Published in SPIE Proceedings Vol. 8421:
OFS2012 22nd International Conference on Optical Fiber Sensors
Yanbiao Liao; Wei Jin; David D. Sampson; Ryozo Yamauchi; Youngjoo Chung; Kentaro Nakamura; Yunjiang Rao, Editor(s)