Gemini Fiber for Interferometry and Sensing Applications

A novel type of fiber for sensing applications is introduced based on a plurality of individual fiber preforms drawn together but maintaining their original shape. The individual cores of the Gemini fiber can be addressed at input and output ends through splicing to stand-alone fibers. Thermal coupling between cores is sufficient to eliminate relative thermal effects. Fabrication, coupling and fiber Bragg grating (FBG) studies are discussed. The possibility to connect in a single splice more than one fiber to the Gemini fiber is introduced as being highly advantageous. A conventional splicer can be used, the loss is acceptable and the operation takes minutes. Sensing with Gemini fibers is discussed mainly with the incorporation of fiber Bragg gratings. Another advantage of the concept of the Gemini fiber discussed is the possibility to make monolithic fiber interferometers of nearly equal arm lengths. A large number of new options are opened by the monolithic multicore fiber design, where access to individual cores is straightforward.