Generation of resonant geometric modes from off-axis pumped degenerate cavity Nd:YVO4 lasers with external mode converters

2020 ◽  
Vol 45 (8) ◽  
pp. 2307
Author(s):  
Hsing-Chih Liang ◽  
Han-Yu Lin
Nanophotonics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 973-981 ◽  
Author(s):  
Han Yao ◽  
Fan Shi ◽  
Zhaoyang Wu ◽  
Xinzhu Xu ◽  
Teng Wang ◽  
...  

AbstractUsing an all-fiber mode selective coupler (MSC) at the visible band, here we experimentally demonstrate a generating and wavelength multiplexing scheme for the cylindrical vector (CV) and vortex beams (VBs). The proposed MSCs act as efficient mode converters to produce spectrally insensitive high-order modes (HOMs) at the wavelength ranging from 450 to 980 nm, which have broad operation bandwidth (more than 7 nm), high mode conversion efficiency (94%), and purity (98%), and low insert loss (below 0.5 dB). By adjusting the polarization state and the phase shift of linear polarization (LP)11 mode respectively, the donut-shaped CVs and circular-polarization VBs are achieved. The focused intensity distribution of the donut beam on the cross- and axial-sections is monitored by using a confocal system. The all-fiber solution of producing and multiplexing HOMs opens a new route for stimulated emission depletion microscopy applications.


2021 ◽  
Author(s):  
Xiaoqian Wang ◽  
Hu Zhang ◽  
Jingxuan Yang ◽  
Xiaoguang Zhang ◽  
Lixia Xi ◽  
...  

Symmetry ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 660 ◽  
Author(s):  
Xiaoqiang Zhang ◽  
Xuesong Wang

Large numbers of images are produced in many fields every day. The content security of digital images becomes an important issue for scientists and engineers. Inspired by the magic cube game, a three-dimensional (3D) permutation model is established to permute images, which includes three permutation modes, i.e., internal-row mode, internal-column mode, and external mode. To protect the image content on the Internet, a novel multiple-image encryption symmetric algorithm (block cipher) with the 3D permutation model and the chaotic system is proposed. First, the chaotic sequences and chaotic images are generated by chaotic systems. Second, the sender permutes the plain images by the 3D permutation model. Lastly, the sender performs the exclusive OR operation on permuted images. The simulation and algorithm comparisons display that the proposed algorithm possesses desirable encryption images, high security, and efficiency.


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