Fig. 2From: Progress of infrared guided-wave nanophotonic sensors and devicesSchematic illustration of the sensing mechanisms of infrared guided-wave nanophotonic biochemical sensing based on evanescent field detection. a RI-based sensor with its surface functionalized to selectively adsorb analyte. The optical signal change in the sensor, e.g., the resonant wavelength shift in a resonator, is known to be induced by the absorbed analyte. b Absorption-based sensor without surface functionalization. The different analytes adsorbed on the sensor surface are distinguished by their induced characteristic absorption peaks at different wavelengths on the sensor transmission spectrumBack to article page