Femtosecond Laser Fabricated Multimode Fiber Sensors Interrogated by Optical-Carrier-Based Microwave Interferometry Technique for Distributed Strain Sensing


A multimode fiber (MMF) based cascaded intrinsic Fabry-Perot interferometers (IFPIs) system is presented and the distributed strain sensing has been experimentally demonstrated by using such system. The proposed 13 cascaded IFPIs have been formed by 14 cascaded reflectors that have been fabricated on a grade index MMF. Each reflector has been made by drawing a line on the center of the cross-section of the MMF through a femtosecond laser. The distance between any two adjacent reflectors is around 100 cm. The optical carrier based microwave interferometry (OCMI) technique has been used to interrogate the MMF based cascaded FPIs system by reading the optical interference information in the microwave domain. The location along with the shift of the interference fringe pattern for each FPI can be resolved though signal processing based on the microwave domain information. The multimode interference showed very little influence to the microwave domain signals. By using such system the strain of 10-4 for each FPI sensor and the spatial resolution of less than 5 cm for the system can be easily achieved.

Meeting Name

SPIE OPTO (2016: Feb. 17-18, San Francisco, CA)


Electrical and Computer Engineering

Keywords and Phrases

Fabry-Perot interferometers; Fiber optic sensors; Fibers; Interferometry; Microwaves; Multimode fibers; Optical instruments; Reflection; Signal interference; Signal processing; Ultrashort pulses; Distributed sensing; Femtosecond laser machining; Fiber Sensor; Interference fringe pattern; Intrinsic Fabry-Perot interferometers; Microwave interferometries; Microwave Photonics; Multi-mode fibers (MMF); Microwave sensors

International Standard Book Number (ISBN)


International Standard Serial Number (ISSN)


Document Type

Article - Conference proceedings

Document Version


File Type





© 2016 SPIE, All rights reserved.

Publication Date

01 Mar 2016