Chirality parameter sensing based on surface plasmon resonance D-type photonic crystal fiber sensors

We report a method to sense a surrounding chiral drug based on D-type single-mode photonic crystal fiber (PCF) sensors in this paper. The electromagnetic theory of surface plasmon resonance on metal-chiral drug structure is derived. The wave equation containing constitutive relations of a chiral drug is given and integrated into the finite element method to compute the effective refractive index, confinement loss, and plasmon resonance wavelength for a D-type PCF sensor immersed in the chiral drug. The effects of the chirality parameter on resonance behaviors are displayed. The wavelength sensitivities of the chirality parameter for the sensor changing with different kinds of metal film layers, side-polished depth, and thickness of metal film layer are calculated. The wavelength sensitivity can reach a maximum of 17,580 nm/chirality as the refractive index and chirality parameter of the drug are 1.36 and 0.08, respectively. Furthermore, simultaneous dual-parameter detection of the chirality parameter and refractive index is realized by using two different D-type PCF sensors with gold and silver metal film layers, respectively. This study may provide sufficient guidelines to the field of biochemical sensing.