Generalized dark hollow sine-Gaussian beam and its propagation properties.

A model of the generalized dark hollow sine-Gaussian beam (GDHsGB) is proposed to uniformly describe both conventional dark hollow beams (DHBs) and anomalous dark hollow beams (ADHBs) with circular or elliptic geometrical patterns. Using the Collins formula, we derive the analytical expression for GDHsGBs propagating in ABCD paraxial optical systems. We analyze the evolution of the intensity pattern and beam width of circular ADHBs, as well as the ellipticity of elliptic ADHBs, providing mathematical expressions for these physical quantities.

Accelerating finite-energy generalized Olver beams.

We propose a new, to the best of our knowledge, and very general finite power beam solution to the paraxial wave equation (PWE) in Cartesian coordinates by introducing an exponential differential operator on the existing PWE solution and term it as the "finite-energy generalized Olver beam." Applying the analytical expressions for the field distributions, we study the evolution of intensity, centroid, and variance of these beams during free-space propagation. Our findings demonstrate that these new beams exhibit a diffraction-resistant profile along a curved trajectory when specific beam conditions are met.

Complex source point theory of paraxial and nonparaxial elliptical Gaussian beams.

Using the operator transformation technology, we extend the circular Gaussian beam based virtual (complex) sources method to investigate the paraxial and nonparaxial propagation properties of the elliptical Gaussian beams (EGBs) with planar or cylindrical wavefronts travelling in free space. The paraxial approximation analysis reveals the self-reappearance and self-focusing propagation features for the EGBs with cylindrical wavefront under proper parameter conditions. We further introduce the nonparaxial theory to derive the analytical expressions for the field distribution of an EGB in free space, and confirm that these intriguing propagation features can still be observed with added nonparaxial correction.

In-situ preparation of silver salts/collagen fiber hybrid composites and their photocatalytic and antibacterial activities.

To promote the utilization of collagen fiber, silver salts/collagen fiber hybrid composites with photocatalytic and antibacterial activities were successfully prepared in this study via the in-situ organic-inorganic process. The surface morphology, chemical composition and structure were discussed. Scanning electron microscopy (SEM) observation showed that the silver salts/collagen fiber hybrid composites were successfully prepared with silver salt particles (300-500 nm) distributing evenly on the surface of collagen fiber.

Virtual sources for coherent combination beams consisting of off-axis Gaussian beams.

Based on the operator transformation technique, the multiple complex point sources required to generate a coherent superposition of waves are introduced and a closed-form analytical expression is derived for this composite wave. From the expression of the composite wave, the paraxial approximation and the nonparaxial corrections of all orders for the corresponding paraxial beam are determined. The paraxial composite beam uniformly represents off-axis Gaussian beams (GBs), sin(cos)-GBs, sinh(cosh)-GBs, nth-order modified Bessel-GBs, and Bessel-GBs with topological charge.

Vortex characteristics of Fraunhofer diffractions of a plane wave by a spiral phase plate limited by pseudoring polygonal apertures.

We introduce a multilevel spiral phase plate (SPP) limited by a pseudoring polygonal aperture (PRPA). Such an SPP has the advantages of easier fabrication and greater suppression of the sidelobes of the diffraction field over that generated with a polygonal aperture (PA). The Fraunhofer diffraction fields generated by an SPP with a PRPA or with a PA have the same topological charge features and a similar diffraction pattern.