Enhancement of Fluorescent Microscopy for Single Molecule Detection (SMD)Based on Third Order Nonlinear Susceptibility; a Computational Study

A new method for improving signal to noise ratio in fluorescent microscopy has been proposed. Proposed method is based on nonlinear excitation of fluorescent labels, where excitation wavelength is far from absorption and emission of fluorescent molecule. By applying this technique background noise (because of excitation wavelength) in detector will be minimized. Nonlinear excitation method is based on third order nonlinear effects and its enhancement in vicinity of metallic nanoparticles and dielectric. Method exploits generation of higher order frequencies. Generated frequencies have definite relation with excitation wavelengths and by this, adjusting the wavelength for proper absorption of fluorescent molecule is possible. We have analyzed suggested method by numerical simulation. We have used Nonlinear Finite Difference Time Domain (NLFDTD) method for computationally solving three dimensional nonlinear Maxwell’s equations. Results show that generated wavelengths (which are needed to be absorbed by fluorescent molecules) is highly localized on corners of structures (gold nanotriangle) which are in vicinity of dielectric (glass substrate). By this, signal to noise ratio regarding background noise will be essentially improved

کلیدواژه ها:

Single Molecule Detection ، Fluorescence Microscopy ، Nonlinear FDTD ، Nanotriangle ، Third Order Nonlinear Susceptibility