Abstract
A compact fiber optic Fabry-Perot (F-P) sensor for simultaneous acoustic and temperature measurement has been proposed in the research. The sensor consists of silicon-glass-silicon sandwich structure by anodic bonding. The air F-P cavity with a circular hole and slots utilizes the deformation of the silicon membrane to realize acoustic measurement, and the silicon F-P cavity utilizes the temperature sensitivity of the refractive index of silicon to realize temperature measurement. The acoustic signal and temperature information could be recovered by acoustic and temperature demodulation method, respectively. The experimental results demonstrate that the sensor has a signal-to-noise ratio (SNR) of 53 dB and the acoustic sensitivity of 4.65 mV/Pa at 21 kHz, and the temperature sensitivity of 123.10 nm/°C at 20 °C∼120 °C. The proposed fiber optic F-P sensor has great potential for simultaneous acoustic and temperature measurement in aviation, due to its compact structure, mass production and immunity to electromagnetic interference.
Highlights
Measurements of acoustic characteristics and temperature are important in aviation industry, such as aeroengine in-duct sound filed and sound radiation from the nozzle for noise control optimization, temperature for health monitoring and combustion performance control [1]
A light wave is emitted by a single frequency laser (SFL) with output power of 6 mW
The reflected light coming back from the sensor passes through the circulator again and is transmitted into a photodetector (PD) and converted into the electric signal, which is shown on the PC via the data acquisition (DAQ) to process further
Summary
Measurements of acoustic characteristics and temperature are important in aviation industry, such as aeroengine in-duct sound filed and sound radiation from the nozzle for noise control optimization, temperature for health monitoring and combustion performance control [1]. Several types of elastic materials have been used as the pressure-sensitive membrane, such as polymer [9], [10], silver [11]–[13], silicon [14], [15] and graphene [16]–[18] These sensors are mainly focused on the measurement of the acoustic signal. Nakamura et al [19] used a single polymer-cylinder-based F-P cavity for measurements of acoustic pressure and temperature They attached a polymer cylinder with 100 μm length and gold film at the end of optical fiber to construct the sensor. Yin et al [21] used a hybrid F-P cavity constructed by silicon and glass materials to achieve static pressure and temperature measurement simultaneously
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