[Study on measurement of liquid refractive index by analyzing SPR spectrum character]

The principle of optic fiber surface plasmon resonance sensor is discussed in detail based on the electromagnetic theory and radial theory in the present paper. The relationship between SPR spectrum resonance wavelength and liquid refractive index is also analyzed. Through relative spectrum measurement technology, SPR spectrum curves, whose resonance wavelength increases with increasing liquid refractive index, were obtained for eight different kinds of chemical liquids. The measurement of concentration of mixed solution including ethanol and glycol was performed by analyzing the spectrum attribute. The experimental results show that the sensing system features simple structure and all light transmitted by fiber. It not only realizes rapid, accurate and real time measurement for target medium, but also can be used in some special situations and easily realize long distance measurement.