Analysis of surface plasmon spectro-angular reflectance spectrum: real-time measurement, resolution limits, and applications to biosensing.

A surface plasmon biosensing technique based on real-time measurement of the spectro-angular reflectance spectrum of a gold surface is presented. A significant improvement in refractive index resolution and drift compensation has been achieved for the spectro-angular technique to demonstrate a biosensing platform that is, in addition, applicable to plasmonic bandgap measurements. Instrumental improvements are detailed and constants for the model bovine serum albumin (BSA):oxacillin bioassay are presented.

Numerical method for high accuracy index of refraction estimation for spectro-angular surface plasmon resonance systems.

An eigenvector analysis based algorithm is presented for estimating refractive index changes from 2-D reflectance/dispersion images obtained with spectro-angular surface plasmon resonance systems. High resolution over a large dynamic range can be achieved simultaneously. The method performs well in simulations with noisy data maintaining an error of less than 10(-8) refractive index units with up to six bits of noise on 16 bit quantized image data. Experimental measurements show that the method results in a much higher signal to noise ratio than the standard 1-D weighted centroid dip finding algorithm.

Enhanced SPR sensitivity using periodic metallic structures.

A sinusoidal silver grating is used to create a six-fold enhancement of the SPR response compared to a flat surface. The grating parameters are chosen to create a surface plasmon bandgap and it is shown that the enhancement of the sensitivity to bulk sample index occurs when operating near the bandgap. The Kretschmann configuration is considered and the Boundary Element Method is used to generate the dispersion curves.

Rigorous coupled wave analysis applied to transmission efficiency of diffractive beam array relays for free-space optical interconnects.

Parallel high-density free-space optical interconnects typically relay multiple channels in an array configuration; thus, they require good uniformity across their aperture for optimum performance. Rigorous coupled wave analysis is used to determine the throughput off-axis diffraction efficiency for Fresnel lenses within a diffractive imaging relay. The rigorous results are compared with scalar theory and show a significant nonuniformity not predicted by scalar theory. However, the polarization sensitivity is found to be negligible for the f-numbers considered (f/2.9 to f/10.2). These results are supported by experiment.