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 characteristics of photoresist surface-relief gratings

Abstract: Theoretical results from rigorous coupled-wave analysis are compared with experimental diffraction characteristics for holographically formed dielectric photoresist surface-relief gratings with deep grooves (greater than a grating period) and high diffraction efficiency (>85%). The angular selectivity (at a fixed wavelength) and the wavelength selectivity (at a fixed angle of incidence) are presented for both TE and TM incident polarizations. Modeling the gratings as a surface-relief modulated half-space and using rigorous coupled-wave analysis are shown to produce good general agreement with the experimentally measured diffraction characteristics.

Linewidth measurement on IC masks and wafers by grating test patterns.

Abstract: Test patterns in the form of diffraction gratings are used for testing and monitoring linewidths on integrated circuit structures. The first and second diffraction orders produed by a laser beam are evaluated to give the width of the grating lines. Measurements on chrome masks show that this technique is accurate to 5% down to linewidths of 0.5 μm. The design of a test set for factory type mask testing is presented. Also, experiments are reported on the testing of patterns on Si wafers directly after. photoresist development and after various etching steps, and an automatic setup for rapid testing of wafers is described.

Experimental high numerical aperture focusing with high contrast gratings

Abstract: We demonstrate high aperture (up to NA∼0.64) three-dimensional focusing in free space based on wavefront-engineered diffraction gratings. The grating lens’ optical response is tailored by spatially varying the grating ridge and groove width in two dimensions to achieve focal lengths of order 100 μm that are crucial for micro-optical applications. The phase profile of the lens includes multiple 2π phase jumps and was obtained by applying an algorithm for finding the optimal path for both phase and amplitude. Experimental measurements reveal a lateral spot size of 5 μm that is close to the size of a corresponding Airy disk.

Multiplexed holographic transmission gratings recorded in holographic polymer-dispersed liquid crystals: static and dynamic studies

Abstract: The optimization of the experimental parameters of two multiplexed holographic transmission gratings recorded in holographic polymer-dispersed liquid crystals is investigated. Two methods are used to record the holograms: simultaneous and sequential multiplexing. These two processes are optimized to produce two multiplexed Bragg gratings that have the same and the highest possible diffraction efficiencies in the first order. The two methods show similar results when suitable recording parameters are used. The parameters of the recorded gratings (mainly the refractive-index modulation) are retrieved by use of an extension of the rigorous coupled-wave theory to multiplexed gratings. Finally, the response of the holograms to an electric field is studied. We demonstrate few coupling effects between the behavior of both gratings, and we expect a possibility of switching from one grating to the other.

82 nm of continuous tunability for an external cavity semiconductor laser

Abstract: A wavelength tunability of 82 nm without mode hopping has been obtained with an external cavity semiconductor laser emitting around 1540 nm by combined rotation/translation of a diffraction grating. This demonstrates for the first time the tunability of an optical oscillator having a spectral purity better than 100 kHz over more than 10,000 GHz.