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.

Diffraction grating transmission efficiencies for XUV and soft x rays.

Abstract: Efficiencies for diffraction of 45–275-eV x rays into orders by interferometrically formed, electrodeposited, gold transmission gratings have been measured on the 4° beam line at the Stanford Synchrotron Radiation Project (SSRP). Anomalous dispersion affects the observed efficiency since the gold is partially transmitting to x rays. Model calculations which include anomalous dispersion are in good agreement with observations. With a suitable choice of material and thickness, a grating can be optimized for a given wavelength range by reducing the zero order transmission and enhancing the higher orders. Even orders are suppressed for a grating with equal slit and wire sizes.

Spatially coherent surface-emitting, grating coupled quantum cascade laser with unstable resonance cavity

Abstract: A surface emitting, unipolar, quantum cascade semiconductor laser is constructed of a multilayer semiconductor structure on a substrate. The laser has doped semiconductor material only of one conductivity type. The laser includes a core region having a larger effective refractive index than cladding regions. The core region includes a plurality of repeat units, each repeat unit having a nominally identical active region and a carrier injection and relaxation region. The repeat units are for quantum cascade generation of a lasing resonance mode within a lasing resonance cavity of the multilayer semiconductor structure. A diffraction grating is fabricated within the multilayer semiconductor structure. The grating resonantly couples diverging counter-propagating traveling wave beams of the laser resonance mode while also diffracting light into an upward direction perpendicular to a grating plane and toward the substrate surface, and also into a downward direction. A mirror reflects the downwardly coupled light toward the upward direction again. The optical distance between reflecting mirror and the grating is selected to combine the reflected light with the upwardly coupled light in-phase as the output beam. A lens-like media structure having an effective refractive index profile that varies quadratically in a direction transverse to the laser resonance cavity is included in the multilayer semiconductor structure. The lowest value of the profile is located at a central portion of the laser. The profile monotonically increases moving away from the central portion. The lens-like media structure interacts with the counter-propagating traveling wave beams to provide single mode output.

Highly Conducting Lamellar Diffraction Gratings

Abstract: We outline an improved root-finding algorithm necessary for the solution of the eigenvalue equation associated with the diffraction formalism for lossy lamellar gratings. A numerical example is presented, demonstrating the adequacy of this technique for a highly-conducting aluminium grating.

Optically Induced Refractive Index Changes in BaTiO3

Abstract: The phenomenon of ``optical damage,'' that is, optically induced changes in the index of refraction, can be used as a form of holographic storage in transparent ferroelectric crystals. In this paper we describe a series of experiments which characterize the optical damage in ferroelectric BaTiO3. This is done by recording in a single crystal of the material a plane wave hologram, i.e., a diffraction grating, with a laser at one wavelength and reconstructing the hologram with a laser at another wavelength. The time‐dependence and steady‐state value of the diffracted light is studied with respect to variations in incident light intensity, temperature, writing wavelength, and grating spacing. A model describing the optical damage, based on the work of Chen [F. S. Chen, J. Appl. Phys. 40, 3389 (1969)] and Johnston [W. D. Johnston, Jr., J. Appl. Phys. 41, 3279 (1970)] is presented and the results explained in terms of this model.

Efficient coupling of surface plasmon polaritons to radiation using a bi-grating

Abstract: A nanostructured surface in the form of a bi-grating is shown to efficiently couple surface plasmon polaritons to free-space radiation in the visible part of the spectrum. Coupling was achieved for all propagation directions of the surface mode and the efficiency found to be independent of the propagation direction, taking a mean value of 60% for the structure examined. The consequences of the findings for emissive devices that make use of surface plasmons are discussed.