Highly Birefringent Optical-Fiberized Slot Waveguide for Miniature Polarimetric Interference Sensors: A Proposal

A new scheme of highly birefringent fiberized slot waveguide (FSW) by post-processing a non-birefringent circular microfiber is proposed for polarimetric interference sensors with ultrasmall sensor heads (tens of micrometers). The different sensing properties of an FSW polarimetric interferometer based on a typical fiber loop mirror are investigated and discussed in detail for refractive index, temperature, and strain measurement. The sensitivity can achieve a high level of >;5×10⁴ nm/refractive index unit (RIU), >;5 nm/°C, and ~1 pm/με for refractive index, temperature, and strain sensing, respectively. Moreover, its strain sensitivity has a large tuning range from negative to positive, and can be used as an ultracompact and highly efficient strain compensator. Together with its high birefringence, unique geometry, and extremely small size, FSW presents wide potential applications in physical, biological and/or chemical sensing areas.