Reconstruction of stochastic nonlinear dynamical models from trajectory measurements.

An algorithm is presented for reconstructing stochastic nonlinear dynamical models from noisy time-series data. The approach is analytical; consequently, the resulting algorithm does not require an extensive global search for the model parameters, provides optimal compensation for the effects of dynamical noise, and is robust for a broad range of dynamical models. The strengths of the algorithm are illustrated by inferring the parameters of the stochastic Lorenz system and comparing the results with those of earlier research. The efficiency and accuracy of the algorithm are further demonstrated by inferring a model for a system of five globally and locally coupled noisy oscillators.

Multilayer volume holographic optical memory.

We demonstrate a scheme for volume holographic storage based on the features of shift selectivity of a speckle reference-wave hologram. The proposed recording method permits more-efficient use of the recording medium and yields greater storage density than spherical or plane-wave reference beams. Experimental results of multiple hologram storage and replay in a photorefractive crystal of iron-doped lithium niobate are presented. The mechanisms of lateral and longitudinal shift selectivity are described theoretically and shown to agree with experimental measurements.

Modeling the grating-formation process in thick bacteriorhodopsin films.

We model the grating-formation process in bacteriorhodopsin films for the interference of two plane waves. We simulate the temporal dependence of grating recording and readout, and we examine the behavior of the diffraction efficiency with respect to exposure, write and read wavelengths, and film parameters such as initial optical density and lifetime of the upper state. Gratings written in thick bacteriorhodopsin films are generally nonuniform and nonsinusoidal owing to the absorption and saturation properties of the material. The simulations also show that one can often obtain optimization of hologram recording and readout by writing and reading at wavelengths far off the peak of the ground-state absorbance spectrum, especially for films with high values of the peak optical density.