Research On Thermo-optic Effect In Liquid Prism

Although the surface plasmon resonance (SPR) technology has been widelyapplied to the detection and analysis in biology, chemistry and physics fields, thestability and the accuracy of the measurement system is still affected by noiseinterference. Particularly, different levels of noise interferences stem from complexenvironment and optical components, etc. Up to date, the realization of temperaturecalibration or temperature compensation for the SPR sensor to improve sensitivity hasbeen widely concerned. On the basis of the new liquid prism structure, the main aim inthis paper is to analyze theoretically and investigate experimentally the change ofthermal induced refractive index (TIRI) in the solution by using the thermo-opticaleffect of multi-media with surface plasmon resonance. The main contents are asfollows:We design right-angle V-groove and realize a new type of liquid prism structure.Meanwhile, an automated SPR system is set up. This design is benefit to clean andmaintain metal films, simplify experimental apparatus and improve the stability of thesystem. Based on this original structure, the basic principle of surface plasmonexcitation is studied in detail. The optimum parameters can be extracted and thesensitivity of measurement system can be enhanced by discussing greatly how toinfluence resonance absorption peak full width at half maximum (FWHM) by the lightsource, the incident wavelength and metal materials. Subsequently, the experimentalprocess is designed and the analysis method of experimental data is proposed. Finally,based on the proposed system, we analyze the refractive index as a function of solutionconcentration by measuring NaCl solution and alcohol solution. The reliableexperimental results indicate that the new system is fit for measure requirements.We establish theoretical model about ambient temperature changes for metal film,BK7glass and deionized water by discussing the temperature characteristics of thedetection system. The refractive indexes of the above mentioned dielectrics areexpressed as a function of temperature. Numerical simulation shows the refractive indexof deionized water is associated with the temperature around environment intimately.Furthermore, we research the refractive index variation of the deionized water underdifferent temperature circumstances and examine the resonance angle by virtue of theexperimental apparatus. Also, the dependence of the refractive index of the deionizedwater on the temperature is analyzed as well as the induced error in experiment isdiscussed.We further explore temperature drift of the detection system and dissect the resonance angle change of absorption solution depending on thermo-optic effect, whichis produced by laser beam directly. Afterwards, a theoretical model of thermal effects attransient and steady states is established. By the application of numerical simulation, thedependence of the two kinds of thermal effects on focal length of the lens and theincident wavelengths is discussed, and the TIRI at the transient and steady states isanalyzed in great detail. As such, the TIRI change of the deionized water at the steadystate, which is related to the level of incident power, is simulated theoretically andvalidated experimentally. The results illustrate the linear relationship between TIRI ofthe deionized water and the incident power, as well as the experimental outcomes arereasonably consistent with the theoretical simulation. As another illustration, theabsorbent nanoparticle solution (NaLuF4:Er3+/Yb3+) is prepared for analyzing theincident power as a function of the refractive index of NaLuF4:Er3+/Yb3+, and exploringthe corresponding the TIRI at the transient and thermo-optic coefficient.