Research Of Prism-Coupled Grating Type SPR Sensors Based On The Double-Dips Method

Surface Plasmon Resonance（SPR）has shown great potential for applications in areas such as environmental contaminants,cancer markers,and food safety.Prism-coupled and grating-coupled sensors,which display the advantages of high sensitivity,quick reaction time,and convenient operation,are examined in this work.Regrettably,generating a superior Figure of Merit（FOM）and high sensitivity for these two sensors is challenging.Based on this,this thesis focuses on optical sensors based on the SPR effect,and investigates the sensing mechanisms of prism-coupled,grating-coupled and prism-coupled grating-type sensors,and proposes an optimized design method that simultaneously and substantially improves the sensitivity and quality factor,thus realizing prism-coupled grating-type SPR sensors with excellent performance.The following are the primary research findings:A new self-referencing sensor is proposed in this thesis using a Na-Au bimetallic composite Zn S dielectric grating and Kretschmann structure.The sensor not only has the benefits of simple operation and quick reaction,but it also overcomes the challenge that conventional sensors cannot simultaneously attain high sensitivity and FOM.By combining prismatic coupling with grating coupling,the sensor effectively excites three surface plasmon waves（SPW）.In achieving the sensor’s self-referencing feature,the SPW generated at the Na-Mg F₂ interface can be used as a reference for the two SPWs generated at the Au-Zn S interface.The sensor’s detection accuracy is improved,and extraneous influences are minimized due to the self-referencing capability.This work introduces the Double-dips Method（DDM）to significantly boost sensitivity,which utilizes the angular resonance shifts of two resonance peaks.Furthermore,stability,high sensitivity,and narrower resonance peaks are all achieved by combining the two metals Na and Au.The Full Width at Half Maximum（FWHM）is narrow because of the high sensitivity,which leads to a high FOM.The sensor’s maximum sensitivity,4390°/RIU,is approximately 5 times more than that of conventional sensors in the Refractive Index（RI）range of 1.330 to 1.347.The sensor’s FOM is 338.68 RIU^-1,which is nearly three times higher than that of conventional sensors,and its maximum FWHM is 3.30°.Its average sensitivity is 1117.65°/RIU.