A low-finesse fiber extrinsic Fabry-Perot interference (EFPI) temperature sensor with high sensitivity, large dynamic range and high repeatability for marine applications is designed, and demonstrated. The use of borosilicate glass as the cavity sensitizing material improves the sensitivity of the sensor. In order to achieve temperature measurement with a large dynamic range and high repeatability, sensor samples with three common coupling methods of hydrogen-oxygen flame (HO), epoxy glue (EG) and glass solder (GS) welding were fabricated and the repeatability in a large temperature range were tested. The sensor fabricated by HO has the best repeatability. A sensitivity of 1.5 nm/°≅ in the temperature range of 10°≅~to 100 °≅, with a repeatability of 0.07 °≅ was demonstrated. The theoretical resolution can reach 0.000667°≅. The sensor has a good application prospect in ocean temperature monitoring.
In this paper, we demonstrate an improved dynamic demodulation system for acoustic sensors based on distributed feedback-fiber laser (DFB-FL). The signal is demodulated using the phase-generated carrier (PGC) demodulation technology based on unbalanced Michelson interferometer (MI). An improved PGC demodulation algorithm is introduced, which solves the problems of light intensity disturbance (LID) and phase modulation depth drift in the traditional PGC demodulation algorithm that affect the demodulation results. The acoustic pressure sensitivity test of a packaged DFB-FL acoustic sensor is carried out to evaluate the performances of the demodulation system, a flat acoustic pressure sensitivity and frequency response curve was achieved in the frequency range of 200 Hz~18 kHz, the wavelength-acoustic sensitivity was about -40.22 dB re. pm/Pa. The amplitude changes of demodulation signal with light intensity and modulation depth are also tested, and it shows that the stability of the demodulation system has been significantly improved.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.