Theoretical Design of a High Sensitivity SPR-Based Optical Fiber Pressure Sensor

A theoretical analysis for a new high-sensitivity pressure sensor based on the surface plasmon resonance (SPR) phenomenon is presented. The device consists a thin metal film deposited on the cladding of a U-shaped optical fiber probe embedded in a silicon rubber block. When the block is under pressure, the bending radius will vary and consequently a shift on the SPR wavelength can be noticed and converted to pressure units. Theoretical simulations using the transfer matrix formalism and the N-layer U-shaped fiber model were developed and implemented for three different metals: gold, copper, and silver. A resolution of 5.9 × 10^-4, 6.3 × 10 ^-4, and 1.3 × 10^-3 kPa can be expected for gold, copper, and silver, respectively for a working range up to 0.12 MPa. The proposed structure reveals to be suitable to high-sensitivity pressure measurements, including industrial operating machinery and R&D applications.