Optical detection and excitation of vibrations in silicon resonator sensors

• Main Author: Tudor, Michael John
• Published: University of Surrey 1988
• Subjects: 534; Vibration detection/optics
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383506

The principle aim of this work was to investigate optical techniques for the excitation and detection of vibrations, at resonance, in Silicon resonator sensors. Two all-fibre detection techniques have been developed: one is based on phase modulation and the other on intensity modulation of the optical wave train. Both detection techniques may be implemented in either single mode or multimode fibre. The choice of measurement technique is determined by the desired system performance and cost. The development of these detection systems naturally led to a study of the properties of the sensors, and the characteristics of a pressure transducer and an accelerometer were investigated; the latter is reported in more detail here. The main characteristics studied were modes of resonance, quality factors, resonant frequency shift with temperature, resonant frequency shift with the measurand and the non-linearity of the resonator. Optical excitation of vibrations at resonance was achieved by using a pulsed laser source directly incident on the resonator. The addition of a thin Chrome layer to the resonator improved the largest optically excited amplitude of vibration by a factor of 9 compared with the uncoated resonator.