Light field

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

Evanescent-wave guiding of atoms in hollow optical fibers.

Abstract: An atom placed in a near-resonant laser field is either attracted to or repelled from regions of high intensity depending on the sign of the laser’s detuning from atomic resonance. We have demonstrated that the optical forces induced by laser light guided in a fiber may be used to reflect atoms from the inner wall of a hollow-core optical fiber in a recent work [1,2]. In that demonstration, light was coupled to the lowest-order grazing incidence mode [3] and the laser frequency was tuned to the red side, so that atoms were attracted to the high-intensity region at the center of the fiber. Atoms guided in this way undergo a series of lossless oscillations in the transverse plane and unconstrained motion along the axis. Atoms can also be guided by the evanescent light field of the glass surface surrounding a hollow fiber. With a detuning on the blue side of resonance, atoms are expelled from the high-intensity-field region near the fiber wall. The intensity in the evanescent field is significant at a distance of .=X/2.rr into the hollow region. Consequently, the atoms are nearly specularly reflected from the potential walls. Atom propagation through the fiber in this case is similar to the propagation of light in a multimode, step-index fiber. Evanescent guiding has several advantages over guiding by grazing incidence modes: heating of the atoms due to spontaneous scattering of photons is small in the evanescent case because the atoms spend most of the time in a dark region away from the high laser intensity at the wall. In the grazing incidence configuration, atoms are guided in the high-intensity region, and consequently the spontaneous scattering rate is relatively high. Furthermore, in evanescentwave guiding, the optical potential is generated by light traveling in lossless guided modes. Small-diameter atomic guides of very long length may be practical. By contrast, grazing incidence optical modes decay exponentially with distance [3], effectively limiting the guiding distance to a

Controlling transverse-wave interactions in nonlinear optics - generation and interaction of spatiotemporal structures

Abstract: It is shown that a new type of instability of a light field in a dissipative medium (spatiotemporal instability, which causes the generation of new types of nonlinear light wave) can be observed by controlling the spatial scale and the topology of the transverse interactions of light fields in a medium with cubic nonlinearity. The excitation conditions for optical reverberators, rotating helical waves, and various dissipative structures are experimentally determined. Transformations and interactions of the structures lead to optical turbulence in both space and time. Physical interpretation of these phenomena is based on the parabolic equation for the nonlinear phase shift. It is found that this theoretical model allows one not only to obtain the excitation conditions but to investigate thoroughly such phenomena as hysteresis and nonlinear interactions of structures.

Stokes vector calculations of the submarine light field in an atmosphere-ocean with scattering according to a Rayleigh phase matrix: Effect of interface refractive index on radiance and polarization

Abstract: A large-scale Monte Carlo program has been written to calculate the complete four-component Stokes vector at any region in a fully inhomogeneous atmosphere-ocean system with inclusion of a stochastic interface. The program uses as input the Mueller matrices for the aerosols in the atmosphere as well as the hydrosols in the ocean. The Mueller matrix for the dielectric interface is also accurately accounted for. Rigorous testing was performed by comparing the Monte Carlo technique with a completely independent invariant imbedding approach; the agreement was excellent. To study the effect of the dielectric interface between atmosphere and ocean we set up a model system consisting of only Rayleigh scattering with a calm ocean, although the program can handle a stochastic boundary as well. Results are presented for both the radiance and degree of polarization at various locations in the atmosphere-ocean system as the refractive index of the dielectric interface varies from 1.338, typical of ocean water, to a value of 1.0 which makes the interface disappear.

I: The Wigner Distribution Function in Optics and Optoelectronics

Abstract: Publisher Summary The Wigner distribution function (WDF) in quantum mechanics is a mathematical tool that correctly yields the expectation values of any function of the coordinates or the momenta. The chapter discusses WDF applications to the characterization of light fields and optical systems and to the problem of coupling optimization between sources and waveguides. Phenomena such as diffraction, interference, coherence, or polarization cannot be managed in the framework of geometrical optics but only within wave optics, where the light field is characterized by a vectorial distribution that satisfies the Helmholtz equation. The applications of the WDF support the assertion that the WDF is a valuable theoretical and experimental tool in optics and optoelectronics. Further expansion of WDF applications will probably result from the recent extension of the WDF definition as a quantum quasiprobability distribution of number and phase and as a wide-band distribution function in signal processing.

Line Assisted Light Field Triangulation and Stereo Matching

Abstract: Light fields are image-based representations that use densely sampled rays as a scene description. In this paper, we explore geometric structures of 3D lines in ray space for improving light field triangulation and stereo matching. The triangulation problem aims to fill in the ray space with continuous and non-overlapping simplices anchored at sampled points (rays). Such a triangulation provides a piecewise-linear interpolant useful for light field super-resolution. We show that the light field space is largely bilinear due to 3D line segments in the scene, and direct triangulation of these bilinear subspaces leads to large errors. We instead present a simple but effective algorithm to first map bilinear subspaces to line constraints and then apply Constrained Delaunay Triangulation (CDT). Based on our analysis, we further develop a novel line-assisted graph-cut (LAGC) algorithm that effectively encodes 3D line constraints into light field stereo matching. Experiments on synthetic and real data show that both our triangulation and LAGC algorithms outperform state-of-the-art solutions in accuracy and visual quality.