Search results for "gratings"
showing 4 items of 34 documents
Optical Field-Induced Mass Transport in Soft Materials
2013
Abstract The dependence of the surface relief formation in amorphous chalcogenide (As 2 S 3 and As-S-Se) and Disperse Red 1 dye grafted polyurethane polymer films on the polarization state of holographic recording light beams was studied. It is shown that the direction of lateral mass transport on the film surface is determined by the direction of light electric vector and photoinduced anisotropy in the film. We propose a photoinduced dielectropfhoretic model to explain the photoinduced mass transport in amorphous films. Model is based on the photoinduced softening of the matrix, formation of defects with enhanced or decreased polarizability, and their drift under the electrical field gradi…
Generation of programmable 3D optical vortex structures through devil’s vortex-lens arrays
2013
Different spatial distributions of optical vortices have been generated and characterized by implementing arrays of devil's vortex lenses in a reconfigurable spatial light modulator. A simple design procedure assigns the preferred position and topological charge value to each vortex in the structure, tuning the desired angular momentum. Distributions with charges and momenta of the opposite sign have been experimentally demonstrated. The angular velocity exhibited by the phase distribution around the focal plane has been visualized, showing an excellent agreement with the simulations. The practical limits of the method, with interest for applications involving particle transfer and manipula…
Single-mode Bragg gratings in tapered few-modes and multimode fibers
2019
We propose the implementation of fiber Bragg gratings in tapered few-mode and multimode fibers to accomplish single-mode operation by reducing the core diameter, while preserving the core-cladding structure. The gratings present a single reflection band, and the device shows low insertion losses after the taper fabrication and the fiber Bragg gratings inscription. The excitation of high-order odd modes in the core of the fiber has been identified as the main loss mechanism; it can be prevented by means of symmetric illumination of the fibers. We also demonstrate the excitation of high-order cladding modes (cladding-air modes) along the taper transitions; these modes can be removed without a…
Synthesis and Holographic Properties of Alkyl 2-Cyanoacetate Acceptor Fragment Containing Push – Pull Type Organic Glasses
2015
We present synthesis, optical and holographic properties of original structure organic glasses based on compounds consisting of three fragments: of N,N-bis(2-(trityloxy)ethyl)-4-vinylaniline or N,N-bis(5,5,5-triphenylpentyl)-4-vinylaniline fragments as electron donating fragment (D), 4H-pyran-4-ylidene fragment as linker(π) and of 2-(trityloxy)ethyl 2-cyanoacetate or 5,5,5-triphenylpentyl 2-cyanoacetate as acceptor (A) fragment. These push-pull (D- π-A) type molecular compounds show good solubility in non-polar solvents (CHCl3 or CH2Cl2) and neat thin films with sufficient optical qualities have been obtained by spin-coating technique. Maxima of UV–VIS absorption in dichloromethane solution…