Date and Time November 5th, 2013 (Tuesday), 2:00 PM
Location Sandford Fleming, SF B560
Host Krishna Kishor

Cavity ring-down technique based on frequency-shifted interferometry

Fei Ye




Many optical sensing applications rely on the detection of minute optical loss variations introduced by some sample. Direct optical loss measurement provides limited sensitivity as a result of light source fluctuation and restricted light-sample interaction length. In the first part of my talk, I am going to introduce several commonly used techniques that can enhance the loss detection sensitivity, including wavelength-modulation spectroscopy (WMS), frequency-modulation spectroscopy (FMS), and cavity ring-down spectroscopy (CRDS). Emphasis will be given to CRDS, in which sample loss information is deduced from the decay rate of an optical pulse trapped in a cavity. Then, I am going to show how cavity ring-down (CRD) measurement can be performed by using frequency-shifted interferometry (FSI), a novel fiber-optic technique developed in our research group. In FSI-CRD, one is able to measure the decay rate of continuous-wave (CW) light propagating in a cavity with slow detection electronics, in contrast to the conventional CRD cases where pulsed light and fast detectors are required. I shall conclude the talk with applications of FSI-CRD in fiber bend loss measurements and sensitive chemical analysis.


Fei Ye received his B.Sc. degree in applied physics in 2006, and M.A.Sc. degree in photonics in 2008, both from the University of Toronto. Recently, Fei successfully defended his Ph.D. work under the Department of Electrical and Computer Engineering at U of T, where he conducts research on a novel fiber-optic sensing scheme called frequency-shifted interferometry (FSI). FSI is a versatile technique that can be used to measure fiber length and dispersion, to interrogate fiber-optic sensor networks, and to perform sensitive analysis on chemicals. Fei is a student member of the Optical Society of America (OSA) and the International Society for Optics and Photonics (SPIE). He is the president of the OSA Student Chapter at the University of Toronto from 2009 to 2013.