Author : Onur Can Akkaya
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (89 download)
Book Synopsis High-sensitivity Thermally Stable Interferometric Acoustic Sensors and Fiber-optic Sensor Networks for Remote Sensing Applications by : Onur Can Akkaya
Download or read book High-sensitivity Thermally Stable Interferometric Acoustic Sensors and Fiber-optic Sensor Networks for Remote Sensing Applications written by Onur Can Akkaya and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical sensors and sensor networks have been the key devices in a number of applications, including remote sensing, underwater acoustic communications, oil exploration, surveillance, seismic surveying arrays, military sonar arrays and structural health monitoring for massive aerospace and wind-energy structures. These applications impose critical specifications both at device level and systems level. In the first part of this dissertation, a high-sensitivity, thermally stable, compact interferometric acoustic sensor with a large bandwidth and high dynamic range will be introduced. The device is based on a photonic-crystal fabricated on a compliant single-crystal silicon membrane, which is placed near the metalized end of a single-mode fiber to form a Fabry-Perot (FP) cavity. We demonstrated high reproducibility in operating wavelength (±1 nm) and fabricated ten FP sensors with measured displacement sensitivities within ±0.3 dB. The response was shown to be polarization independent and thermally stable. We showed that ±65 °C change in temperature can be tolerated before the FP resonance shifts by only 1 nm. An experimental sensor was shown to measure acoustic pressures down to a record low of 5.6 μPa/√Hz with a flat-band response greater than 8 kHz and a sensitivity extending down to at least 100 Hz. The dynamic range in pressure was greater than 100 dB. An electromechanical model of the device is presented as a tool for designing and optimizing this micro-physical structure. This analytical model enabled the analysis of the coupled design parameters on the device's sensitivity and noise. Results are shown to be in very good agreement with the experimentally measured quantities. In the second part of the dissertation, the design of a time-division-multiplexed optical sensor network architecture employing multiple low-gain erbium-doped fiber amplifiers will be introduced. Using this architecture, an experimental system will be demonstrated with ten acoustic sensors multiplexed and interrogated with a single laser source at a single wavelength. The signal-to-noise-ratio for each sensor response was measured to be within ±0.95 dB of the nominal value. System performance in terms of cross-talk and polarization dependence will also be discussed. Finally, a model identifying the noise contributions in this complex system will be introduced, which predicts that up to 350 sensors can be multiplexed with this new multiplexing architecture.
