Band-stop angular filtering with hump volume Bragg gratings

Abstract

A band-stop angular filter (BSF) based on hump volume Bragg gratings (HVBGs) is proposed. Band-stop filtering in a two-stage amplifier laser system is discussed and simulated. Simulation results show that small-scale self-focusing effects in the laser system can be effectively suppressed with the BSF due to the control of fast nonlinear growth in a specific range of spatial frequencies in the laser beam. Near-field modulation of the output beam from the laser system was decreased from 2.69 to 1.37 by controlling the fast nonlinear growth of spatial frequencies ranging from $0.6~\text{mm}^{-1}$ to $1.2~\text{mm}^{-1}$ with the BSF. In addition, the BSF can be used in a plug-and-play scheme and has potential applications in high-power laser systems.

The control of fast nonlinear growth in picosecond laser

“…Two-dimensional angular-selectivity filters and hybrid filters were proposed, and realized the filtering of MHFs components of the beam. Gao Fan et al [10] proposed a band-stop filtering technology based on the hump Bragg volume grating, it can separate the specific MHFs components from other frequencies components, so as to realize the so-called band-stop filtering and the filter was called a BSF. Wang Xin et al [11] researched the nanosecond laser directly amplify through the two-stage laser amplification system, and then use the VBGs to perform band-stop filtering, which can improve the near field uniformity of the laser beam and avoid the SSSF.…”

Multi-wavelength carpet cloaking based on an ultrathin single layer metamaterial microstructure

“…Metamaterials, an artificial material, have attracted widespread attention due to their effective characteristics related to electromagnetic wave manipulation. Many functional devices and unusual electromagnetic phenomena have been realized based on metamaterials [1,2], such as the super lens [3], negative refraction [4,5], beam steering structure [6], cloaking devices [7][8][9][10], and so on. In particular, cloaking devices can render an object invisible to electromagnetic waves.…”