Numerical study of multilayer surface Plasmon resonance for biosensing application using III-V semiconductor GaSb

Abstract

The phenomenon of Surface Plasmon Resonance (SPR) takes place at metallic surfaces like Gold and Silver, when light is incident on the surface at resonance angle. An increase in the thickness of a molecular layer at the metal surface reduces the reflected light intensity in graded manner. A change in the refractive index of the sensing medium results a shift in SPR signal. That makes SPR a useful optics based bio sensing technique for bio molecular interactions in real time.GaSb is a III-V direct band gap semiconductor already known for its good opto-electronic applications. The numerical study of three and four layer traditional prism-based SPR assembly was done with Gold and/or GaSb replacing the gold.The change of the resonance angle by the influence of the incident wavelength as well as change in refractive index was simulated. For different thickness, refractive indices and metallic replacements, change in intensity of reflected radiation is reported as well as shift in resonance angle. The refractive index of the water changes with the salinity, so SPR corresponding to salinity change can be used for bio entities determination that causes a change in salinity.