D-Shaped PCF With Quasi-Sinusoidal Surface Topography for Dual-Polarization and Enhanced Performance Surface Plasmon Resonance Sensor

A novel D-shaped photonic crystal fiber (PCF) with quasi-sinusoidal surface is fabricated and experimentally demonstrated for dual polarization surface plasmon resonance (SPR) sensor. The new surface topography enables SPR at transverse magnetic (TM) and transverse electric (TE) propagating modes with polarization-dependent propagation and coupling losses, a rare phenomenon in D-shaped optical fibers which paves the way for enhanced sensing performance and reconfigurable propagation and SPR coupling losses in D-shaped PCF using the suitable polarization state of the input light. The experimental results show that signal propagation loss can be significantly reduced by 3.92 dB/cm when operating the sensor in TE mode which facilitates wide detection range of analyte's refractive index (RI) between 1.3310 up to 1.4226 with noise-free SPR spectral dip. The sensor has maximum sensitivity of 6667 nm/RIU, with good linear response up to RI = 1.3858. The fabricated PCF is endlessly single-moded which provides stable data collection over time with high degree of measurement repeatability. The proposed design is a reliable sensor probe for a wide range of applications in biosensing and chemical sensing due to its stable operation, adjustable losses, and simple analyte infiltration.