Negative Curvature Hollow-Core Photonic Crystal Fibers Sensitivity to Acoustic Vibration in the Audible Spectrum

Hollow-Core Photonic Crystal Fibers (HC-PCF) offer a number of advantages over conventional single-mode (SM) optical fibers. In addition to their evaluation of transmission parameters, it is also necessary to deal with their sensitivity to acoustic vibrations, and thus the possibility of use as a sensor. A homodyne Mach-Zehnder interferometer (MZI) was used to assess its sensitivity, while for a reference arm the G.657 fiber was used and HC-PCF for sensing arm. The entire measurement took place in an anechoic chamber with reference measurement of both the acoustic signal source and the use of reference microphones for background noise measurement. The measurement results show a sensitivity to acoustic vibrations up to a frequency of 3 kHz, with a higher sensitivity in the lower frequency band, which could make it possible to significantly increase the sensitivity of today's sensors operating in this frequency range. The results contribute to the understanding and potential application of hollow fibers in distributed optical sensing.