CiteULike: dchen's optical

Optical Spin-to-Orbital Angular Momentum Conversion in Inhomogeneous Anisotropic Media

L Marrucci — 2008-05-05T16:01:46-00:00

Physical Review Letters, Vol. 96, No. 16. (2006)

We demonstrate experimentally an optical process in which the spin angular momentum carried by a circularly polarized light beam is converted into orbital angular momentum, leading to the generation of helical modes with a wave-front helicity controlled by the input polarization. This phenomenon requires the interaction of light with matter that is both optically inhomogeneous and anisotropic. The underlying physics is also associated with the so-called Pancharatnam-Berry geometrical phases involved in any inhomogeneous transformation of the optical polarization.

Controllable Snail-Paced Light in Biological Bacteriorhodopsin Thin Film

Pengfei Wu — 2008-05-04T19:36:43-00:00

Physical Review Letters, Vol. 95, No. 25. (2005)

We observe that the group velocity of light is reduced to an extremely low value of 0.091 mm/s in a biological thin film of bacteriorhodopsin at room temperature. By exploiting unique features of a flexible photoisomerization process for coherent population oscillation, the velocity is all-optically controlled over an enormous span, from snail-paced to normal light speed, with no need of modifying the characteristics of the incident pulse. Because of the large quantum yield for the photoreaction in this biochemical system, the ultraslow light is observed even at low light levels of microwatts, indicating high energy efficiency.

Chiral Molecules Split Light: Reflection and Refraction in a Chiral Liquid

Ambarish Ghosh — 2006-11-14T23:28:28-00:00

Physical Review Letters, Vol. 97, No. 17. (2006)

A light beam changes direction as it enters a liquid at an angle from another medium, such as air. Should the liquid contain molecules that lack mirror symmetry, then it has been predicted by Fresnel that the light beam will not only change direction, but will actually split into two separate beams with a small difference in the respective angles of refraction. Here we report the observation of this phenomenon. We also demonstrate that the angle of reflection does not equal the angle of incidence in a chiral medium. Unlike conventional optical rotation, which depends on the path-length through the sample, the reported reflection and refraction phenomena arise within a few wavelengths at the interface and thereby suggest a new approach to polarimetry that can be used in microfluidic volumes.

Nonlinearity Management in Optics: Experiment, Theory, and Simulation

Martin Centurion — 2008-05-04T18:54:49-00:00

Physical Review Letters, Vol. 97, No. 3. (2006)

We conduct an experimental investigation of nonlinearity management in optics using femtosecond pulses and layered Kerr media consisting of glass and air. By examining the propagation properties over several diffraction lengths, we show that wave collapse can be prevented. We corroborate these experimental results with numerical simulations of the (2+1)-dimensional focusing cubic nonlinear Schrödinger equation with piecewise constant coefficients and a theoretical analysis of this setting using a moment method.

Polymeric Quasicrystal: Mesoscopic Quasicrystalline Tiling in ABC Star Polymers

Kenichi Hayashida — 2008-05-04T16:23:48-00:00

Physical Review Letters, Vol. 98, No. 19. (2007)

A mesoscopic tiling pattern with 12-fold symmetry has been observed in a three-component polymer system composed of polyisoprene, polystyrene, and poly(2-vinylpyridine) which forms a star-shaped terpolymer, and a polystyrene homopolymer blend. Transmission electron microscopy images reveal a nonperiodic tiling pattern covered with equilateral triangles and squares, their triangle/square number ratio of 2.3 (4/), and a microbeam x-ray diffraction pattern shows dodecagonal symmetry. The same kind of quasicrystalline structures have been found for metal alloys (~0.5 nm), chalcogenides (~2 nm), and liquid crystals (~10 nm). The present result (~50 nm) confirms the universal nature of dodecagonal quasicrystals over several hierarchical length scales.

Strong Photon Nonlinearities and Photonic Mott Insulators

Michael Hartmann — 2008-05-03T19:49:30-00:00

Physical Review Letters, Vol. 99, No. 10. (2007)

We show that photon nonlinearities in an electromagnetically induced transparency can be at least 1 order of magnitude larger than predicted in all previous approaches. As an application we demonstrate that in this regime they give rise to very strong photon-photon interactions which are strong enough to make an experimental realization of a photonic Mott insulator state feasible in arrays of coupled ultrahigh-Q microcavities.

Ghost-imaging experiment by measuring reflected photons

Ron Meyers — 2008-05-03T16:01:55-00:00

Physical Review A (Atomic, Molecular, and Optical Physics), Vol. 77, No. 4. (2008)

A CCD array is placed facing a chaotic light source and gated by a photon counting detector that simply counts all randomly scattered and reflected photons from an object. A “ghost” image of the object is then observed in the gated CCD. Differing from all published ghost-imaging experiments, this setup captures ghosts from scattered and reflected light of an object, instead of the transmitted ones. This new feature is not only useful for practical applications, but is also important fundamentally. It further explores the nonclassical interference nature of thermal light ghost imaging.

On-chip natural assembly of silicon photonic bandgap crystals

Yurii Vlasov — 2008-05-02T20:48:07-00:00

Nature, Vol. 414, No. 6861. (15 November 2001), pp. 289-293.

Optically Anisotropic Colloids of Controllable Shape

A Fernández-Nieves — 2008-04-23T21:34:08-00:00

Advanced Materials, Vol. 17, No. 6. (2005), pp. 680-684.

No abstract.