Topic
Near and far field
About: Near and far field is a research topic. Over the lifetime, 15922 publications have been published within this topic receiving 220571 citations.
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TL;DR: In this paper, the influence of lateral fiber vibrations on the lateral resolution in scanning near field optical lithography using a tapered optical fiber was discussed, where the fiber tip acts as a subwavelength sized light source to perform high-resolution photolithography in a commercial linear photoresist.
70 citations
TL;DR: In this article, a solution for computing the transmission characteristics of a slit in a conducting screen of finite thickness placed between two different media was developed, where the slit may be filled with Iossy material while the two regions on either side of the screen are assumed Iossless.
Abstract: A solution is developed for computing the transmission characteristics of a slit in a conducting screen of finite thickness placed between two different media. The slit may be filled with Iossy material while the two regions on either side of the screen are assumed Iossless. A magnetic line source excitation is used (TE case) which is parallel to the axis of the slit. The equivalence principle is invoked to replace the two slit faces by equivalent magnetic current sheets on perfect electric conductors. Two coupled integral equations containing the magnetic currents as unknowns are then obtained and solved for by the method of moments. Pulses are used for the expansion and testing functions. Quantities computed are equivalent magnetic currents, the transmission coefficient, the gain pattern, and the normalized far field pattern.
70 citations
TL;DR: In this article, a multijunction system that laterally splits the solar spectrum onto a planar array of single-junction cells with different band gaps is proposed, which achieves an average splitting ratio of 69.5% between visible and near-infrared light over the 380-970 nm range at normal incidence.
Abstract: The greatest source of loss in conventional single-junction photovoltaic cells is their inefficient utilization of the energy contained in the full spectrum of sunlight. To overcome this deficiency, we propose a multijunction system that laterally splits the solar spectrum onto a planar array of single-junction cells with different band gaps. As a first demonstration, we designed, fabricated, and characterized dispersive diffractive optics that spatially separated the visible (360–760 nm) and near-infrared (760–1100 nm) bands of sunlight in the far field. Inverse electromagnetic design was used to optimize the surface texture of the thin diffractive phase element. An optimized thin film fabricated by femtosecond two-photon absorption 3D direct laser writing shows an average splitting ratio of 69.5% between the visible and near-infrared light over the 380–970 nm range at normal incidence. The splitting efficiency is predicted to be 80.4% assuming a structure without fabrication errors. Spectral-splitting a...
70 citations
TL;DR: In this article, an array of photoconducting antennas which generates electrically controllable millimeter-wave and sub-millimeterwave radiation in free space is described, where the emitted radiation is directional and electrically steerable, and can be scanned through an angle of over 40 degrees.
Abstract: An array of photoconducting antennas which generates electrically controllable millimeter-wave and submillimeter-wave radiation in free space is described. Under quasi-sinusoidal optical illumination, the emitted radiation is directional and electrically steerable, and can be scanned through an angle of over 40 degrees . The center of the scanning range can be adjusted by changing the angle of incidence of the pump beam. The far-field radiation pattern of the array is measured and discussed. Also, some properties of the array under illumination by a short optical pulse are demonstrated. These include electrical control of the frequency content of the signal and mapping of the spatial profile of the applied electric field onto the radiated waveform. The latter property can be used to multiplex information presented in parallel into a train of radiated pulses with a bit spacing of 6 ps. >
70 citations
TL;DR: In this article, explicit formulae are given for both the far field radiation and the sound reflected back up the pipe for an incident plane wave, which are valid to second order in the ratio of duct diameter to wavelength, in excellent agreement with Munt's exact numerical computations.
70 citations