  In this paper we report a fiber optical sensor system based on surface
plasmon resonance (SPR) with real-time response for biochemical interaction
analysis. The fiber sensor is constructed from a multi-mode fiber with plastic
cladding. To facilitate the measurement, a software program is developed which
integrates the data acquisition and processing for real-time feedback.
Polynomial fitting is implemented to smooth out the noise in the transmission
ratio and a spectral resolution of 0.2 nm is achieved. Ethyl alcohol and water
mixtures with different concentrations are measured to demonstrate the system's
real-time capability. This work is essential for the development of a compact,
real-time fiber SPR biosensor.
