Optical vortex convolution generator and quasi-Talbot effect.

In this Letter, a simple optical vortex convolution generator is proposed where a microlens array (MLA) is utilized as an optical convolution device, and a focusing lens (FL) is employed to obtain the far field, which can convert a single optical vortex into a vortex array. Further, the optical field distribution on the focal plane of the FL is theoretically analyzed and experimentally verified using three MLAs of different sizes. Moreover, in the experiments, behind the FL, the self-imaging Talbot effect of the vortex array is also observed.

Completely revealing the amplitude properties of Laguerre-Gaussian vortex beams.

In this paper, the amplitude properties of the Laguerre-Gaussian (LG) vortex beams are analyzed theoretically and demonstrated experimentally. Firstly, the ring width of the LG vortex beam is almost a constant, which can be considered to be independent of the topological charge (l) and only determined by the waist radius ω(z), and its general expression is derived via investigating Lambert W function. On this basis, concise expressions for inner and outer ring radii, ratio of inner and outer ring radius, ring area and beam divergence are also given out.

A comparative evaluation of the activities of thiol group and hydroxyl group in low-frequency vibrations using terahertz spectroscopy and DFT calculations.

Low-frequency vibrations of biomolecules govern many biological processes like allostery of proteins, binding interaction and solvation. Revealing how involved are different groups of molecules in low-frequency vibrations is of significance to understand the behaviors of biomolecules. To compare the activities of hydroxyl group and thiol group in low-frequency vibrations, we conducted THz measurements and DFT calculations of l‑serine and l‑cysteine.