24 April 2001 Diffractive focusing of wide-aperture beams: theory and experiment
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Proceedings Volume 4270, Laser Resonators IV; (2001) https://doi.org/10.1117/12.424669
Event: Photonics West 2001 - LASE, 2001, San Jose, CA, United States
Abstract
It is shown theoretically and experimentally that when a Gaussian beam illuminates a bicomponent diffraction system with small Fresnel numbers, consisting of two plane screens with circular apertures on given optical axes, in a near zone of the second screen the effect of diffractive multifocal focusing of radiation is observed. In this case, the diffraction picture from the second screen in the focal planes represents the circular nonlocal bands of the Fresnel zones with a bright narrow peak at the center, whose intensity can exceed by six times the value of the incident wave intensity. The proposed diffractive method allows the focusing of the wide-aperture beams without using classical refraction elements such as lenses and prisms, and it is applicable to both low-intensive and high-power radiation. The energy efficiency of diffractive focusing of Gaussian beams is as high as 70%. Such a method can improve the energy efficiency of the fiber coupling of diode lasers and can increase the intensity of radiation on a fiber exit up to a factor of ten.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Renat R. Letfullin, Oleg A. Zayakin, Thomas F. George, "Diffractive focusing of wide-aperture beams: theory and experiment", Proc. SPIE 4270, Laser Resonators IV, (24 April 2001); doi: 10.1117/12.424669; https://doi.org/10.1117/12.424669
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