Abstract

In order to improve the resolution of phase modulated surface plasmon resonance (SPR) measurement technology, the phase difference signal processing technology is optimized. For the phase SPR sensor based on Mach–Zehnder interferometer (MZI), we innovatively use a voice coil motor (VCM) as a phase modulation device. The SPR phase can be extracted by comparing the phase difference of interference signal of s and p polarizations after their reflection. The waveforms of s and p polarizations are detected by two photodetectors connected with a data acquisition (DAQ) device and a computer. According to the mathematical theory and signal processing technology, interference optical signal is selected and processed through choice of logical conditions. The phase difference of signal is analyzed in real time. Based on the proposed signal processing technology, the fluctuation of phase difference is less than 0.006° and resolution can reach 4.7×10^-7 RIU.

© 2018 The Author(s)