Influence of PDMS encapsulation on the sensitivity and frequency range of fiber-optic interferometer

摘要

Fiber-optic sensors are one of the dynamically developing areas of photonics and photonic applications. This group of sensors can also include fiber-optic interferometers which enable very sensitive sensing. They are entirely passive regarding power supply, and immune to electromagnetic interference. This type of sensor is dependent on the phase change. It mostly used in the field which requires high measurement accuracy. We can achieve a change of sensitivity in the order of 10-8. The fundamental problem of fiber-optic interferometry is a design and imposition (encapsulation) of the measuring arm and reference arm of the interferometer. Polydimethylsiloxane elastomer (PDMS) is one of the possibilities to encapsulation of the sensory arm. Two-component PDMS Sylgard 184 is used type. The article analyzes the effect of encapsulation into a PDMS of the measuring arm of the interferometer to frequency response and sensitivity of the Mach-Zehnder interferometer with the division of power in a ratio of 1:1 (measuring arm and reference arm). Input power set to a reference value of 1 mW, this value was constant for all performed experimental measurements. The generator of a harmonic signal with fixed amplitude signal used for analysis of the frequency characteristic of the interferometer. The application written in LabView development environment, evaluated the amplitude-frequency spectra of the signal. Repeated test of assembled prototype verified the measured results.