scholarly journals Phase singularities of an ultrasonic speckle field back-scattered from an underwater Gaussian interface

2014 ◽  
Vol 63 (5) ◽  
pp. 054301
Author(s):  
Zheng Wei-Hua ◽  
Jia Hu
Keyword(s):  
Speckle Field ◽  
Phase Singularities ◽  
Ultrasonic Speckle

Revealing a scattering object from the spatial distribution of phase singularities in a speckle field

2021 ◽  
Author(s):  
Oleg V. Angelsky ◽  
Andrew P. MAKSIMYAK ◽  
Peter P. Maksimyak ◽  
Igor O. Mokrienko
Keyword(s):  
Spatial Distribution ◽  
Speckle Field ◽  
Phase Singularities

scholarly journals Phase singularities of speckle field produced by the scattering from Gaussian correlation random surfaces

2009 ◽  
Vol 58 (8) ◽  
pp. 5376
Author(s):  
Liu Man ◽  
Cheng Chuan-Fu ◽  
Song Hong-Sheng ◽  
Teng Shu-Yun ◽  
Liu Gui-Yuan
Keyword(s):  
Random Surfaces ◽  
Speckle Field ◽  
Phase Singularities

scholarly journals Integrated Double-Sided Random Microlens Array Used for Laser Beam Homogenization

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 673
Author(s):  
Wei Yuan ◽  
Cheng Xu ◽  
Li Xue ◽  
Hui Pang ◽  
Axiu Cao ◽  
...  
Keyword(s):  
Laser Beam ◽  
Microlens Array ◽  
Energy Utilization ◽  
Utilization Rate ◽  
Periodic Lattice ◽  
Lattice Distribution ◽  
Speckle Field ◽  
High Laser ◽  
Alignment Problem ◽  
In Series

Double microlens arrays (MLAs) in series can be used to divide and superpose laser beam so as to achieve a homogenized spot. However, for laser beam homogenization with high coherence, the periodic lattice distribution in the homogenized spot will be generated due to the periodicity of the traditional MLA, which greatly reduces the uniformity of the homogenized spot. To solve this problem, a monolithic and highly integrated double-sided random microlens array (D-rMLA) is proposed for the purpose of achieving laser beam homogenization. The periodicity of the MLA is disturbed by the closely arranged microlens structures with random apertures. And the random speckle field is achieved to improve the uniformity of the homogenized spot by the superposition of the divided sub-beams. In addition, the double-sided exposure technique is proposed to prepare the rMLA on both sides of the same substrate with high precision alignment to form an integrated D-rMLA structure, which avoids the strict alignment problem in the installation process of traditional discrete MLAs. Then the laser beam homogenization experiments have been carried out by using the prepared D-rMLA structure. The laser beam homogenized spots of different wavelengths have been tested, including the wavelengths of 650 nm (R), 532 nm (G), and 405 nm (B). The experimental results show that the uniformity of the RGB homogenized spots is about 91%, 89%, and 90%. And the energy utilization rate is about 89%, 87%, 86%, respectively. Hence, the prepared structure has high laser beam homogenization ability and energy utilization rate, which is suitable for wide wavelength regime.

scholarly journals Moiré pattern of interference dislocations in condensate of indirect excitons

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J. R. Leonard ◽  
Lunhui Hu ◽  
A. A. High ◽  
A. T. Hammack ◽  
Congjun Wu ◽  
...  
Keyword(s):  
Long Range ◽  
Direct Measurement ◽  
Quantum Systems ◽  
Matter Waves ◽  
Moire Pattern ◽  
Indirect Excitons ◽  
Moiré Pattern ◽  
Moiré Effect ◽  
Phase Singularities ◽  
Bose Einstein

AbstractInterference patterns provide direct measurement of coherent propagation of matter waves in quantum systems. Superfluidity in Bose–Einstein condensates of excitons can enable long-range ballistic exciton propagation and can lead to emerging long-scale interference patterns. Indirect excitons (IXs) are formed by electrons and holes in separated layers. The theory predicts that the reduced IX recombination enables IX superfluid propagation over macroscopic distances. Here, we present dislocation-like phase singularities in interference patterns produced by condensate of IXs. We analyze how exciton vortices and skyrmions should appear in the interference experiments and show that the observed interference dislocations are not associated with these phase defects. We show that the observed interference dislocations originate from the moiré effect in combined interference patterns of propagating condensate matter waves. The interference dislocations are formed by the IX matter waves ballistically propagating over macroscopic distances. The long-range ballistic IX propagation is the evidence for IX condensate superfluidity.

scholarly journals Wavefront dislocations reveal the topology of quasi-1D photonic insulators

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Clément Dutreix ◽  
Matthieu Bellec ◽  
Pierre Delplace ◽  
Fabrice Mortessagne
Keyword(s):  
Local Density ◽  
Topological Defects ◽  
Wave Functions ◽  
Topological Classification ◽  
Local Density Of States ◽  
Topological Phase Transition ◽  
Interference Fringes ◽  
Classical Wave ◽  
Phase Singularities

AbstractPhase singularities appear ubiquitously in wavefields, regardless of the wave equation. Such topological defects can lead to wavefront dislocations, as observed in a humongous number of classical wave experiments. Phase singularities of wave functions are also at the heart of the topological classification of the gapped phases of matter. Despite identical singular features, topological insulators and topological defects in waves remain two distinct fields. Realising 1D microwave insulators, we experimentally observe a wavefront dislocation – a 2D phase singularity – in the local density of states when the systems undergo a topological phase transition. We show theoretically that the change in the number of interference fringes at the transition reveals the topological index that characterises the band topology in the insulator.

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