Analysis of wavelength-scale 1D depth-dependent refractive-index gradients at an interface by their effects on the internal reflectance near the critical angle.

Light's internal reflectivity near a critical angle is very sensitive to the angle of incidence and the optical properties of the external medium near the interface. Novel applications in biology and medicine of subcritical internal reflection are being pursued. In many practical situations, the refractive index of the external medium may vary with respect to its bulk value due to different physical phenomena at surfaces.

Optical reflectivity of an interface with random refractive-index-contrast patterns.

We develop simple models for the optical reflectivity of an interface in optical contact with random media consisting of discrete volumes of arbitrary form and different refractive indices. Examples of interest are surfaces sprinkled with microdroplets or an interface with biological cells adhered to it at random locations. We focus our attention to the case of internal reflectivity, in which the incidence medium has a larger refractive index than the refractive indices at the other side of the interface.

Analytical modeling of optical reflectivity of random plasmonic nano-monolayers.

In this paper, we compare three different models that have been used to interpret reflectivity measurements of supported monolayers of nanoparticles. Two of them: (i) isotropic Maxwell Garnett and (ii) anisotropic two-dimensional-dipolar model are based on an effective-medium approach, while the third one (iii) coherent-scattering model, lies within the framework of multiple-scattering theory. First, we briefly review, on physical grounds, the foundations of each model and write down the corresponding formulas for the calculation of the reflectivity.

Reflectivity and transmissivity of a surface covered by a disordered monolayer of large and tenuous particles: theory versus experiment.

The main objective of this paper is to endorse a recently derived theoretical model for the coherent reflectance and transmittance from a surface supporting a disordered monolayer of large and tenuous particles by comparison with experimental measurements. The model is based on the so-called anomalous-diffraction approximation and is assumed to be valid for small and moderate angles of incidence. We prepared disordered monolayers of spherical polystyrene particles of 1.

Collimated light reflection and transmission of a surface partially covered by large and tenuous particles.

We derive simple approximate expressions for the reflectivity and transmissivity of light from disordered monolayers of tenuous particles of dimensions larger than the wavelength and supported by a flat interface. The expressions derived can be used for different particle shapes and for moderate angles of incidence. We then investigate the effects of particle shape and orientation on reflectivity and transmissivity spectra of a monolayer of tenuous particles containing an optical chromophore in a solution in their interior.

Optical reflectivity of a disordered monolayer of highly scattering particles: coherent scattering model versus experiment.

Recently a multiple-scattering model for the reflectivity of a disordered monolayer of scattering particles on a flat surface was put forth [J. Opt. Soc.