Our article entitled Addressing Challenges in Fabricating Reflection-Based Fiber Optic Interferometers has been published in the journal Sensors.
In our work to study phase-transitions by use of fiber optic sensors, we found that their fabrication requires accurate control to obtain reproducible results. In the paper, we evaluate the consequences of practical challenges in fabricating reflection-based, fiber optic interferometers by the use of theory and experiments. A guided-mode propagation approach is used to investigate the effect of the end-face cleave angle and the accuracy of the splice in core-mismatched fiber optic sensors. Cleave angles from high-end fiber cleavers were found to give differences in optical path lengths approaching the wavelength close to the circumference of the fiber, and the core-mismatched splice decided the ensemble of cladding modes excited. In the paper, we show that the cleave angle may significantly alter the spectrum, whereas the splice is more robust. We found that the interferometric visibility can be decreased by up to 70% for cleave angles typically obtained. An offset splice may reduce the visibility, but for offsets experienced experimentally the effect is negligible. We found that an angled splice did not affect the visibility but caused a lower overall intensity in the spectrum. The insight presented in this work has helped us to improve the phase transition studies.
The work was done in collaboration with Markus Wahl and Dag Roar Hjelme from the Department of Electronic Systems at NTNU.