Multipath Interferometer Polished Microsphere for Enhanced Temperature Sensing

A multipath interferometer based on a polished multimode microsphere is proposed for temperature sensing. Asymmetry was introduced in the structure by polishing the microsphere with a certain angle. A new set of optical paths are generated in the polished microsphere due to the different reflections inside of the structure. The interference between the different optical paths can be seen as the superposition of several two-wave interferometers, which can be discerned through signal processing. Intensity exchange between different components of the interferometer was observed when changing the temperature. The temperature sensitivity is more than three-fold for smaller cavities. Moreover, a sensitivity enhancement is also verified if a correlation method is used. In such a case, the sensitivity to temperature is even higher than just considering smaller cavities.