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Temperature sensing with enhanced sensitivity based on the spectral interference of polarization modes in a highly birefringent (HB) fiber is proposed and demonstrated. A temperature sensor employs a tandem configuration of a birefringent quartz crystal and HB fiber placed between an analyzer and a polarizer. In the setup a modified channeled spectrum is generated, which shifts with the temperature change of the sensing part of the HB fiber. We analyze the measurement method theoretically and show that the sensitivity of the temperature sensing based on the wavelength interrogation is enhanced in comparison to a standard method with a fiber interferometer. We also demonstrate the enhancement of the temperature sensitivity for three HB fibers under test. Experimental results show that the temperature sensing can reach a sensitivity of −0.30 nm/K, which is enhanced in comparison to −0.10 nm/K reached for a standard measurement. [ABSTRACT FROM AUTHOR]

A highly sensitive measurement of the displacement of an interferometer mirror based on spectral interferometry and Vernier effect is proposed and demonstrated. The displacement measurement employs two interferometers in tandem, an interferometer represented by a combination of a polarizer, a birefrigent quartz crystal and an analyzer, and a Michelson interferometer. In the setup the Vernier effect is generated and the resultant channeled spectrum is with the envelope which shifts with the displacement of the interferometer mirror. We analyze the new measurement method theoretically and show that the sensitivity of the displacement measurement based on the wavelength interrogation is substantially increased in comparison to a standard method with a Michelson interferometer. We also demonstrate the realization of the measurement setup in which the position of the interferometer mirror is controlled via a closed-loop piezo positioning system. Experimental results show that the displacement measurement can reach a sensitivity of 264 nm/μm, which is substantially increased in comparison to −34 nm/μm reached for a standard measurement. [ABSTRACT FROM AUTHOR]