title: Dynamic interrogator for elastic wave sensing using Fabry Perot filters based on fiber Bragg gratings.
abstract: Use of in-fiber Fabry-Perot (FP) filters based on fiber Bragg gratings as both sensor as well as an interrogator for enhancing the detection limit of elastic wave sensing is investigated in this paper. The sensitivity of such a demodulation scheme depends on the spectral discrimination of the sensor and interrogator gratings. Simulations have shown that the use of in-fiber FP filters with high finesse provide better performance in terms of sensitivity compared to the demodulation using fiber Bragg gratings. Based on these results, a dynamic interrogator capable of sensing acoustic waves with amplitude of less than 1 micro-strain over frequencies of 10 kHz to several 100 kHz has been implemented. Frequency response of the fiber Bragg gratings in the given experimental setup has been compared to that of the conventional piezo sensors demonstrating that fiber Bragg gratings can be used over a relatively broad frequency range. Dynamic interrogator has been packaged in a compact box without any degradation in its performance.
authors.affiliation: Department of Electrical Engineering, IIT Madras, Chennai 600036, India.
authors.forename: Achar V
authors.initials: AV
authors.lastname: Harish
authors.affiliation: Department of Electrical Engineering, IIT Madras, Chennai 600036, India.
authors.forename: Bibin
authors.initials: B
authors.lastname: Varghese
authors.affiliation: Indira Gandhi Center for Atomic Research, Kalpakkam 603102, India.
authors.forename: Babu
authors.initials: B
authors.lastname: Rao
authors.affiliation: Department of Mechanical Engineering, IIT Madras, Chennai, 600036, India.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Balasubramaniam
authors.affiliation: Department of Electrical Engineering, IIT Madras, Chennai 600036, India. Electronic address: balajis@ee.iitm.ac.in.
authors.forename: Balaji
authors.initials: B
authors.lastname: Srinivasan
keywords: Acousto optics; Dynamic interrogator; Fabry Perot filters; Fiber Bragg grating