We propose and demonstrate experimentally a non-contact optical fiber displacement sensor based on bidirectional modulation of a Mach-Zehnder electro-optical modulator (MZ-EOM), which consists mainly of a tunable laser, MZEOM, optical collimator, specular object, and photodetector. The relationship between the free spectral range (FSR) and the displacement variation for the proposed scheme is given. The FSR is determined by the dip frequencies with the transfer function of the bidirectional modulation of an MZ-EOM and depends on the travel time. As a result, the FSRs according to the displacement variation are presented via both simulation and experiments. The experimental results for the several displacements using micro-stage and piezo-stack in the frequency range of 100 MHz to 300 MHz show a good agreement with the theoretical analysis. The measured sensitivities for the proposed scheme by using the FSR and the dip frequency shift show 437 kHz/mm and 1203 kHz/mm, respectively.

Date Published: 1 July 2015
PDF: 4 pages
Proc. SPIE 9655, Fifth Asia-Pacific Optical Sensors Conference, 96550H (1 July 2015); doi: 10.1117/12.2184397

Published in SPIE Proceedings Vol. 9655:
Fifth Asia-Pacific Optical Sensors Conference
Byoungho Lee; Sang-Bae Lee; Yunjiang Rao, Editor(s)