Observation Of Light Propagation Research Articles

Observation of light propagation across a 90° corner in chains of microspheres on a patterned substrate

To demonstrate light-path manipulation in arbitrary shapes we fabricated coupled-resonator optical waveguides (CROWs) having a 90 degrees-corner structure on a lithographically patterned substrate. The spectra of propagation light within the CROWs were directly measured by guide-collection-mode near-field scanning optical microscopy. The spectra revealed that the propagation light through the CROWs has a larger transverse-magnetic polarization mode than a transverse-electric (TE) one. The most plausible cause of the lower intensity in the TE mode is that light leaks out to the Si substrate.

Light propagation in a porous silicon waveguide: an optical modes analysis in near‐field

AbstractWe report on the first near‐field observation of light propagation in a porous silicon planar waveguide. The observation has been made possible using a scattering‐type scanning near field optical microscope (s‐SNOM). Optical constants of the propating modes are retrieved by two methods first, from the intensity profile and then from the complex field profile, the latter being obtained with a heterodyne interferometric setup. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Observation of light propagation by holography with a picosecond pulsed laser

We demonstrate the propagation of a light pulse undergoing refraction and total refraction inside a glass block as well as diffraction at a grating. Observation of a frameless, continuous motion picture of the light propagation is possible by recording of hologram with a picosecond pulsed laser. It is shown that the direction of the pulse changes as a result of refraction, the pulse's speed decreases inside a glass block, and the pulse travels a zigzag path by total refraction. The pulse fronts of the diffracted light propagating parallel to the grating surface are also demonstrated.

Observation of light propagation in two-dimensional photonic crystal-based bent optical waveguides

An observation of light propagation in a two-dimensional photonic crystal-based (2D–PC) optical waveguide is reported. Bent waveguides with a bending angle of 60° embedded in a 2D–PC triangular lattice with air columns were fabricated on a molecular-beam epitaxially grown AlGaAs/GaAs structure. The light-propagation characteristics were examined by observing scattered light from PC regions with incident light in the 850–950 nm range under an optical microscope using a charge coupled device camera. The incident light was strongly guided for wavelengths corresponding to the photonic band gap.

Observation of Light Propagation in Single Layers of Composite Two-Dimensional Arrays

Composite two-dimensional (2D) polystyrene (PSt) arrays, composed of three types of PSt particles, red fluorescent, green fluorescent, and nonfluorescent, were prepared from an aqueous suspension. These arrays form as a result of water evaporation and capillary forces. Using fluorescence microscopy and phase-contrast microscopy, we observed several interesting types of light propagation phenomena in single layers of the array, including anisotropic light propagation, an additive effect for light intensity, and a novel switch function. These characteristic light propagation phenomena indicate some of the possibilities of the 2D array as a photonic device.

Observation of light propagation in photonic crystal optical waveguides with bends

Observation of light propagation in photonic crystal optical waveguides with bends Light propagation is investigated in two-dimensional photonic crystal waveguides with bends, which were composed of closely-packed holes formed in a GaInAsP thin film. Wavelength and polarisation dependence on propagation characteristics were observed in the wavelength range 1.47–1.60 µm.

Observation of light propagation in volume scatterers with 10^11-fold slow motion

An optical method is introduced for observation of temporally and spatially resolved frames that show how light propagates in diffusely scattering materials. The method permits videos with 100-fs resolution in time to be produced. The method utilizes short-coherence interferometry. The source of information is the speckle contrast. The temporal and spatial evolution of the multiple scattering process is demonstrated for several biological and industrial samples. A major objective of the method is to investigate the conditions for optimum coherence and optimum apertures to achieve high resolution in the short-coherence interferometry. One important result is that during the propagation a sharp photon horizon evolves, which is useful for the morphological analysis of volume scatterers.