An Inline Core-Cladding Intermodal Interferometer Using a Photonic Crystal Fiber

We propose a simple all-fiber structure based on intermodal interference between a core and a cladding mode of an endlessly single-mode photonic crystal fiber (PCF) section sandwiched between a lead-in and lead-out SMF-28 fiber. We have measured the intermodal dispersion and the polarization-dependent loss (PDL) of the structure. The sensitivities to strain, pressure, and temperature and external refractive index are studied. The interferometer is compared to an interferometer based on LP
₀₁
-LP
₀₂
SMF-28 fiber and to a PCF-based tapered LPG.