Diffraction grating

About: Diffraction grating is a research topic. Over the lifetime, 24884 publications have been published within this topic receiving 372437 citations. The topic is also known as: grating.

Polarization independent enhanced optical transmission in one-dimensional gratings and device applications.

Abstract: A review and analysis is performed of various resonance effects associated with subwavelength one-dimensional (1-D) metal gratings for transverse electric (TE) and transverse magnetic (TM) polarized incident radiation. It is shown that by tuning the structural geometry (especially the groove width) and material composition of the 1-D gratings, polarization independent enhanced optical transmission (EOT) can be achieved. Three different cases of EOT have been studied for 1-D metal gratings: a) EOT for TM-polarized incident radiation b) EOT for TE-polarized incident radiation, and most importantly c) EOT for un-polarized incident light. Potential uses of these results in the design and improvement of various optoelectronic devices, such as polarizers, photodetectors and wavelength filters are discussed.

Experimental demonstration of a narrowband, angular tolerant, polarization independent, doubly periodic resonant grating filter.

Abstract: Resonant grating filters are promising components for free-space narrowband filtering. Unfortunately, due to their weak angular tolerance, their performances are strongly deteriorated when they are illuminated with a standard collimated beam. Yet this problem can be overcome by resorting to a complex periodic pattern known as the doubly periodic grating [Lemarchand et al., Opt. Lett.23, 1149 (1998)]. We report what we believe to be the first experimental fabrication and characterization of a bidimensional doubly periodic grating filter. We obtained a 0.5 nm bandpass polarization independent reflection filter for telecom wavelengths (1520-1570 nm) that presents a transmittivity minimum of 18% with a standard incident collimated beam.

Compact Beam Expander with Linear Gratings

Abstract: Novel compact beam expanders that could be useful for applications such as providing light to flat panel displays are presented. They are based on a planar configuration in which three spatially linear gratings are recorded on one transparent substrate, so as to expand a narrow incoming beam in two dimensions. We present the design and recording procedures along with results, showing a relatively uniform intensity of the wide output beam. Such expanders can serve for illuminating flat panel displays.

Linearized field theory of a Smith-Purcell traveling wave tube

Abstract: A linearized field theory of a grating-coupled Smith-Purcell traveling-wave tube (TWT) is presented. The configuration describes the propagation of a magnetized, sheet electron beam through a parallel-plate waveguide in which two opposing faces of the waveguide consists of either 1) a pair of identical diffraction gratings (referred to as a double-sided configuration) or 2) a diffraction grating along one face and a flat plate along the opposing face (referred to as a single-sided configuration). This is a two-dimensional formulation since we assume the configuration is uniform in the direction parallel to the slots in the grating. For each of these configurations, we derive the linearized dispersion equations for the vacuum structures and the wave-particle interaction in both the infinitely strong magnetic field limit and for an arbitrary (solenoidal) magnetic field. A discussion of the extraction efficiency based on phase-trapping arguments is also presented. An example of a W-band Smith-Purcell TWT is discussed.

Programmable fiber optic delay line

Abstract: This paper describes a novel programmable delay line that generates up to 50 ns of true time-delay in discrete 10 ns intervals. The delay line consists of an externally modulated wavelength tunable fiber laser and a six-element wavelength multiplexed fiber Bragg grating array, with the grating spacing set to yield the desired delay. >