Light field

About: Light field is a research topic. Over the lifetime, 5357 publications have been published within this topic receiving 87424 citations.

Intuitive explanation of the phase anomaly of focused light beams

Abstract: An intuitive argument is presented for the phase anomaly, that is, the 180° phase shift of a light wave in passing through a focus. The treatment is based on the geometrical properties of Gaussian light beams, and suggests a new viewpoint for understanding the origin of the phase shift. Generalizing the argument by including higher-order modes of the light field allows the case of a spherical wave to be treated.

Optical control of molecular dynamics: Molecular cannons, reflectrons, and wave‐packet focusers

Abstract: We consider the control of molecular dynamics using tailored light fields, based on a phase space theory of control [Y. J. Yan et al., J. Phys. Chem. 97, 2320 (1993)]. This theory enables us to calculate, in the weak field (one‐photon) limit, the globally optimal light field that produces the best overlap for a given phase space target. We present as an illustrative example the use of quantum control to overcome the natural tendency of quantum wave packets to delocalize on excited state potential energy curves. Three cases are studied: (i) a ‘‘molecular cannon’’ in which we focus an outgoing continuum wave packet of I2 in both position and momentum, (ii) a ‘‘reflectron’’ in which we focus an incoming bound wave packet of I2, and (iii) the focusing of a bound wave packet of Na2 at a turning point on the excited state potential using multiple light pulses to create a localized wave packet with zero momentum. For each case, we compute the globally optimal light field and also how well the wave packet produced by this light field achieves the desired target. These globally optimal fields are quite simple and robust. While our theory provides the globally optimal light field in the linear, weak field regime, experiment can in reality only provide a restricted universe of possible light fields. We therefore also consider the control of molecular quantum dynamics using light fields restricted to a parametrized functional form which spans a set of fields that can be experimentally realized. We fit the globally optimal electric field with a functional form consisting of a superposition of subpulses with variable parameters of amplitude, center time, center frequency, temporal width, relative phase, and linear and quadratic chirp. The best fit light fields produce excellent quantum control and are within the range of experimental possibility. We discuss relevant experiments such as ultrafast spectroscopy and ultrafast electron and x‐ray diffraction which can in principle detect these focused wave packets.

Measurement-induced diffraction and interference of atoms

Abstract: The position of an atom passing through a standard light wave is localized by making a quadrature phase measurement on the light field. This localization can be thought of as the creation of a virtual slit (or slits) for the atom by the field measurement. Diffraction and interference behavior may be observed in the far field.

Electro-optic quantum memory for light using two-level atoms.

Abstract: We present a simple quantum memory scheme that allows for the storage of a light field in an ensemble of two-level atoms. The technique is analogous to the NMR gradient echo for which the imprinting and recalling of the input field are performed by controlling a linearly varying broadening. Our protocol is perfectly efficient in the limit of high optical depths and the output pulse is emitted in the forward direction. We provide a numerical analysis of the protocol together with an experiment performed in a solid state system. In close agreement with our model, the experiment shows a total efficiency of up to 15%, and a recall efficiency of 26%. We suggest simple realizable improvements for the experiment to surpass the no-cloning limit.

Lazy decompression of surface light fields for precomputed global illumination

Abstract: This paper describes a series of algorithms that allow the unconstrained walkthrough of static scenes shaded with the results of precomputed global illumination. The global illumination includes specular as well as diffuse terms, and intermediate results are cached as surface light fields. The compression of such light fields is examined, and a lazy decompression scheme is presented which allows for high-quality compression by making use of block-coding techniques. This scheme takes advantage of spatial coherence within the light field to aid compression, and also makes use of temporal coherence to accelerate decompression. Finally the techniques are extended to a certain type of dynamic scene.