Fiber-optic Surface Plasmon Resonance Sensor Based On Phase Interrogation

Surface plasmon resonance(SPR)sensors,which have the advantages of high sensitivity,real-time and label-free detection,et al,are widely used in fields of biological research,drug discovery,food safety,and environmental monitoring.Compared with other interrogation techniques,phase detection is the most sensitive excitation monitoring method for SPR sensing.However,the narrow dynamic range has greatly limited the versatility and applicability of phase sensitive SPR sensors.In this paper,the sensitivity and resolution of the sensing system can be improved and the dynamic range would be extremely expanded,which is based on the combination of phase modulation interferometry and fiber-optic SPR technique.For the reason that the coupled plasmon waveguide resonance(CPWR)in transverse electric(TE)mode is employed as the sensing signal,the signal-to-noise ratio of sensor has been greatly enhanced.At the same time,the accuracy requirement of the length of the sensing area has been reduced.The main contents of this paper include:1.The research background and development of surface plasmon resonance sensors have been introduced in this paper.The structure and performance characteristics of various SPR sensors based on different coupling modes,film structures and interrogation techniques are analyzed.Then,the deficiencies of the phase modulation SPR sensors and the research significance of this work are discussed.2.The basic theories of surface plasmon resonance and phase modulation interferometry are analyzed.And then,the phase interrogation techniques used in SPR sensors are introduced,including optical heterodyne,ellipsometry,shear interferometry,spatial phase modulation interferometry and temporal phase modulation interferometry.3.The principles of fiber-optic SPR sensors are analyzed in this work.Then the main parameters of the sensing system,such as the incidence angle,wavelength,the refractive index and thickness of the metal layer and the waveguide layer,et al,are discussed through simulation analysis.4.A fiber-optic SPR sensor based on phase interrogation is designed.And the main performance indexes of the sensing system in different working modes are discussed by simulation analysis.When the SPR sensor is working in the 2rd order CPWR of TE mode,the resolution of the sensing system on average will be 3.43×10~-77 RIU(Refractive Index Unit)and the dynamic range of refractive index of the sample solution will been extended to 0.444 RIU.