Abstract
An experiment is proposed to show the feasibility of using hollow-core photonic bandgap fibers (HC-PBF) in the fiber-optic interferometric stethoscopes to generally improve the sensitivity and overcome the problems associated with the electronic stethoscopes. In the experiment, the HC-1550 is used as a measuring arm of an unbalanced Mach-Zehnder interferometer (MZI) and the conventional single-mode optical fiber (SMF) is used as an isolated reference arm. Detection and demodulation of the relative phase shift is performed passively using phase-generated carrier homodyne technique (PGC). The proposed results indicate the significance of using HC-PBFs in the future stethoscopes.
Highlights
Stethoscopes are important devices for the early diagnosis of heart dysfunction
The used optical fibers in the previous related work were either the conventional single-mode optical fiber (SMF) or the solid-core photonic crystal fibers (SC-PCF) that have structures reduce its sensitivity to the acoustomechanical signals generated by the patient
We propose an experiment to preliminary study the use of hollow-core photonic bandgap fibers (HC-PBF) stethoscopes to improve the performance of the existing conventional stethoscopes and provide even better performance than using conventional SMF
Summary
Stethoscopes are important devices for the early diagnosis of heart dysfunction. The current electronic stethoscopes have some advantages over traditional stethoscopes such as the ability to amplify output sound which is important especially in noisy environment or emergency areas, enhancing the frequency range, reducing the ambient noise, and recording, replaying, and visual displaying of the output data. In [10], a MZI strain sensor was constructed and used to compare the normalized strain responsivity (NR) of the HC-PBF with the conventional SMF by interchanging the optical fibers under test as a sensing arm of the MZI. The aim of the experiment is to implement the concept of using the HCPBF in the optical fiber interferometric stethoscope system, how it can interact with the applied signals, and how the measurand’s relevant information is extracted by the PGC demodulation technique. The experiment is performed using a Mach-Zehnder interferometer in which light from a single-mode laser diode is split by an optical fiber coupler into the sensing HC-1550 arm which is wrapped around the piezoelectric transducer cylinder (PZT) and a reference SMF fiber that is isolated from the PZT strains. The high sensitivity of HC-PBF stethoscope allows it to replace the conventional piezoelectric crystal used in the electronic stethoscopes and the conventional SMF in the existing optical fiber stethoscopes
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