Photonic crystal fiber with selective infiltration for high sensitivity simultaneous temperature and strain measurement

A selectively infiltrated photonic crystal fiber integrated with an embedded directional coupler and a multi-mode interferometer is fabricated by infiltrating three adjacent air holes of the innermost layer with standard 1.48 refractive index liquids. The light propagated between the fiber core and the rods can efficiently be coupled into the satellite waveguides under the phase-matching conditions Furthermore, there is a multi-mode interference produced by fiber core modes and rod high order modes. Such a compact device is demonstrated for high sensitivity simultaneous temperature (∼14.72 nm/°C) and strain (∼13.01 pm/μs) measurement.