Patent ID: 7349590

Claim:
An optical interrogation system for interrogating a grating-coupled waveguide sensor, said optical interrogation system comprising: a light source capable of outputting a polarized light beam; a polarization modulator capable of modulating the polarized light beam and outputting a polarization-modulated light beam; said grating-coupled waveguide sensor capable of receiving the polarization-modulated light beam and converting the polarization-modulated light beam into an amplitude modulated light beam; a light beam scanning device capable of angular scanning or wavelength scanning the polarization-modulated light beam prior to being directed towards said grating-coupled waveguide sensor or capable of angular scanning or wavelength scanning the amplitude modulated light beam received from said grating-coupled waveguide sensor; a detector capable of receiving the amplitude modulated light beam and further capable of converting the amplitude modulated light beam into an electrical signal; a lock-in amplifier capable of receiving the electrical signal from said detector and further capable of demodulating the electrical signal a computer capable of analyzing the demodulated electrical signal to detect a resonant condition which indicates whether a biological substance is located in a sensing region of said grating-based waveguide sensor; and a function generator capable of synchronizing said polarization modulator and said lock-in amplifier.