Microfiber Knot Resonators as Sensors A Review

Abstract

Microfiber knot resonators find application in many different fields of action, of which an important one is the optical sensing. The large evanescent field of light can interact and sense the external medium, tuning the resonance conditions of the structure. The resonant property of microfiber knot resonators can also provide, in some cases, an enhancement in the sensing capability. Until nowadays, a wide variety of physical and chemical parameters have been possible to measure with this device. New developments and improvements are still being done in this field. A review on microfiber knot resonators as sensors is presented, with particular emphasis on their application as temperature and refractive index sensors. The properties of these structures are analyzed and different assembling configurations are presented. Important aspects in terms of the sensor stability are discussed, as well as alternatives to increase the sensor robustness. In terms of new advances, an overview on coated microfiber knot resonators is also presented. Finally, other microfiber knot configurations are explored and discussed.