Analysis of the D-shaped PCF-based SPR sensor using Resonance Electron Relaxation and Fourier domain method

Since the D-shaped photonic crystal fiber (PCF) based Surface Plasmon Resonance (SPR) sensor is an important tool in scientifical research and applications, a new concept of Resonance Electron Relaxation (RER) is defined to investigate its detection property. It successfully explains the 'S-shape' profile in the dispersion and the wave-length delay between the dispersion intersection and loss peak. The birefringence interference has also been analyzed with the RER phenomenon. Then we experimentally demonstrated the SPR sensing performance. A fast Fourier transform (FFT) algorithm is applied in the experiment to separate each component signal in the spatial frequency domain. Then using a band passing filter of 0.001-0.006 nm-1 together with inverse FFT algorithm, the distinguished SPR spectrum shows a significant agreement with theoretical simulations, with differences of only 14.3 nm and 1.48% in resonance wavelength and intensity. This study facilitates a high precision analysis and data process approach for the SPR sensor based on D-shaped PCF and presents greatly promising application prospects in SPR sensors.