Enhanced Surface Plasmon Resonance (SPR) sensitivity with nano- and micro- structuration of plasmonic films

A. Dhawan, M. Chamtouri, J. Singh, T. Ashok, M. Besbes, J. Moreau, H. Ghalila, M. Canva
Indian Institute of Technology-Delhi, IN

Keywords: SPRI, biosensing, bulk sensing, localized plasmons, propagating plasmons

Summary:

Surface Plasmon Resonance Imaging (SPRI) systems are powerful label free real time surface evolution characterization tools that can be used for many applications including biochip reading. Most plasmonic biochip applications are currently based on propagative plasmon (PP) on a flat homogeneous metallo-dielectric interface. From the optical perspective, maximal sensitivities are close to their limits if one only uses such PP modes. On another hand, in the relatively newer field of nanosciences and nanotechnology, much research effort is devoted to the localized plasmons (LP) mode that can be generated using nanoparticles. We study both two dimensional (line gratings) and three dimensional structuration (with different base geometries) of the thin metallic film, varying periodicity as well as filling factors, in a wide spatial range from nanometers to micrometers, and also particle shape and planar packing type in the case of the 3D structuration. Theoretical simulations are being carried on by means of Rigorous Coupled Wave Analysis (RCWA), Finite Difference Time Domain (FDTD), as well as hybrid simultaneously using Finite Elements and Fourier Modal Methods (FEM+FMM). Substrate fabrications have been done using different techniques including E-beam, deep UV lithography and soft-sphere lithography.