Enhanced sensitivity of polydimethylsiloxane Fabry-Perot interferometer temperature sensor

A polydimethylsiloxane (PDMS) Fabry-Perot interferometer placed at the end of single-mode optical fiber is proposed and demonstrated experimentally. The temperature sensitivity of the interferometer 2.5 nm /°C in the range 28 °C to 35 °C was achieved. To enhance the sensitivity of the temperature sensor another interferometer (in Mach-Zehnder configuration) was used. In this case the sensitivity is enhanced by Vernier effect. The temperature sensitivity was enhanced to 14.8 nm/°C what is almost 6 times higher. Interesting attribute of such configuration is possibility to change free spectral range (FSR) of the second interferometer due to optical path difference settings. So, it is possible to change the sensitivity of the sensor.