Cosine-Gaussian-correlated Schell-model sources whose degree of coherence (DOC) is of circular symmetry have been introduced just recently [Opt. Lett. 38, 2578 (2013)]. In this Letter, we propose a model for a source whose DOC is the superposition of two 1D cosine-Gaussian-correlated Schell-model sources, i.e., possesses rectangular symmetry. The novel model sources and beams they generate are termed rectangular cosine-Gaussian Schell-model (RCGSM). The RCGSM beam exhibits unique features on propagation, e.g., its intensity in the far field (or in the focal plane) displays a four-beamlet array profile, being qualitatively different from the ring-shaped profile of the CGSM beam whose DOC is of circular symmetry. Furthermore, we have carried out experimental generation of the proposed beam and measured its focusing properties. Our experimental results are consistent with the theoretical predictions.
A new kind of partially coherent beam with non-conventional correlation function named generalized multi-Gaussian correlated Schell-model (GMGCSM) beam is proposed. The GMGCSM beam of the first or second kind is capable of producing dark hollow or flat-topped beam profile in the focal plane (or in the far field). Furthermore, we carry out experimental generation of a GMGCSM beam of the first or second kind, and measure its focused intensity. Our experimental results verify theoretical predictions. The GMGCSM beam will be useful for free-space optical communications, material thermal processing, particle or atom trapping.
In classical optical imaging, the Rayleigh diffraction limit d R is defined as the minimum resolvable separation between two points under incoherent light illumination. In this paper, we analyze the minimum resolvable separation between two points under partially coherent beam illumination. We find that the image resolution of two points can overcome the classic Rayleigh diffraction limit through manipulating the correlation function of a partially coherent source, and the image resolution, which independent of the specified positions of two points in the object plane, can in principle reach the value of 0.17d R. Furthermore, we carry out an experimental demonstration of sub-Rayleigh imaging of a 1951 USAF resolution target via engineering the correlation function of the illuminating beam. Our experimental results are in agreement with our theoretical predictions.
It is theoretically predicted in [Opt. Lett.37, 1553 (2012)] that a full Poincaré (FP) beam can significantly reduce turbulence-induced scintillation. In this paper, we propose a method for synthesizing a FP beam for different beam orders and report experimental generation of the first-, second- and third-order FP beams. Furthermore, we carry out experimental measurement of the scintillation index of a FP beam passing through thermally induced turbulence. It is demonstrated that the FP beam indeed can significantly reduce the scintillation index compared to a Gaussian beam under certain conditions. Our results will be useful in long-distance free-space optical communications.
We study theoretically and experimentally the influence of the obstacle position separation from the source on the self-healing capacity of partially coherent beams using Hermite-Gaussian correlated Schell-model beams as a case in point. We establish that the shorter the distance between the obstacle and the source plane and the longer the distance between the obstacle and the observation (receiver) plane, the better the self-healing capacity of the beams. In addition, a similarity degree between the reconstructed and original beams is introduced to quantify the self-healing capacity of partially coherent beams. The derived interesting results may find applications in optical information processing, image transmission, and recovery.
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