Diffraction efficiency

About: Diffraction efficiency is a research topic. Over the lifetime, 10320 publications have been published within this topic receiving 158298 citations.

Zone plates with high efficiency in high orders of diffraction described by dynamical theory

Abstract: The coupled wave theory is applied to calculate the diffraction efficiency of zone plates used in high orders of diffraction. In contradiction to the existing understanding about 30%–50% of the incident intensity can be diffracted by a single high order if the line-to-space ratio of the zone structures is in the range of 0.1–0.5 and the aspect ratios are larger than 30:1. Highly efficient diffractive transmission x-ray optics with high numerical apertures and resolving power can be developed without manufacturing extremely small zones which are necessary for zone plates used in the first order.

Parallel photopolymerisation with complex light patterns generated by diffractive optical elements

Abstract: Photopolymerisation by scanning a focused laser beam is a powerful method to build structures of arbitrary complexity with submicrometer resolution. We introduce parallel photopolymerisation to enhance the efficiency. Instead of multidimensional scanning of a single focus, the structure is generated simultaneously with diffractive patterns. We used fixed diffractive optical elements (DOEs), kinoforms, and Spatial Light Modulators (SLMs). The possibilities of photopolymerisation using SLM were investigated: the added flexibility using the programmable device is demonstrated. By using these DOEs, straight and helical cross shaped columns were produced with a single scan at a rate about an order of magnitude faster than by simple scanning. The produced helical structures could be rotated by optical tweezers.

Polarization insensitive imaging through polarization gratings.

Abstract: Liquid crystal polarization gratings exhibit high diffraction efficiency (~ 100%) in thin material layers comparable to the radiation wavelength. We demonstrate that they can be combined for polarization-insensitive imaging and optical switching applications. A pair of closely spaced, parallel oriented, cycloidal polarization gratings is capable of canceling the diffractive property of an individual grating. As a result, the phase of the beam is not distorted, and holographic images can be formed through them. An anti-parallel arrangement results in a broader effective diffraction band and doubles the diffraction angle. Broadband diffraction spanning from 480 nm to beyond 900 nm wavelengths has been obtained for a pair of gratings with 500 nm and 633 nm peak diffraction wavelengths. Liquid crystal polymer cycloidal gratings were used in the study showing 98% diffraction efficiency over a large area, and allowed for the use of laser beams expanded to 25 mm. The characteristics of combined cycloidal gratings were tested with laser beams at both UV and red wavelengths.

Diffraction grating with a spatially varying duty-cycle

Abstract: A diffractive optical element is disclosed. The optical element comprises a grating having a periodic linear structure in at least one direction. The linear structure is characterized by non-uniform duty cycle selected to ensure non-uniform diffraction efficiency.

Design and fabrication of binary slanted surface-relief gratings for a planar optical interconnection

Abstract: We propose the use of binary slanted surface-relief gratings with parallel-groove walls as input and output couplers in a planar optical interconnect. Parametric optimization of cascaded output couplers is employed to design an interconnect consisting of N output couplers producing a uniform intensity distribution with a high efficiency that may be realized in one lithographic etching step. The sensitivity of a N = 4 interconnect to various fabrication errors is analyzed. We demonstrate the operation of a slanted surface-relief grating manufactured with electron-beam lithography and reactive-ion etching for an operating wavelength of λ = 0.633 μm.