Far-field pattern formation by manipulating the topological charges of square-shaped optical vortex lattices

Stoyanov, Lyubomir; Maleshkov, Georgi; Zhekova, Maya; Stefanov, Ivan; Neshev, Dragomir N.; Paulus, G. G.; Dreischuh, A.

doi:10.1364/josab.35.000402

“…rhomboidal OV lattices, periodic kagome lattices, and to quasi-periodic patterns (Penrose, decagonal; see the systematic description in 12 ). These results, in addition to the previously published ones 11 , may appear particularly interesting, as a new degree of freedom, for modifications in stimulated emission depletion (STED) microscopy, for extending the possibilities of generating singular higher-order vector fields 15 , for controllable writing of parallel optically-induced waveguide structures e.g. in (photorefractive) nonlinear media (see, e.g.…”

Section: Resultsmentioning

confidence: 52%

“…The stability of square-shaped OV lattices in both self-focusing and self-defocusing nonlinear media is demonstrated in 8 (Figs. 11 and 12) as well as in linear media 11 . The discrete nondiffracting beams, which are one of the four different families of such beams, are characterized and summarized in 12 (see also the references therein).…”

Section: Introductionmentioning

confidence: 99%

Controllable beam reshaping by mixing square-shaped and hexagonal optical vortex lattices

Stoyanov

¹

,

Maleshkov

²

,

Zhekova

³

et al. 2019

Sci Rep

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8

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In the present work we show experimentally and by numerical calculations a substantial far-field beam reshaping by mixing square-shaped and hexagonal optical vortex (OV) lattices composed of vortices with alternatively changing topological charges. We show that the small-scale structure of the observed pattern results from the OV lattice with the larger array node spacing, whereas the large-scale structure stems from the OV lattice with the smaller array node spacing. In addition, we demonstrate that it is possible to host an OV, a one-dimensional, or a quasi-two-dimensional singular beam in each of the bright beams of the generated focal patterns. The detailed experimental data at different square-to-hexagonal vortex array node spacings shows that this quantity could be used as a control parameter for generating the desired focused structure. The experimental data are in excellent agreement with the numerical simulations.

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“…As a matter of fact, optical vortices have attracted attention for their diverse photonic applications ranging from optical tweezers 43 , 44 , quantum computation 45 , enhancement of astronomical images 46 . In all these applications, optical vortex lattices are always involved and necessary 47 – 50 . These vortex lattices require sophisticated and complex experimental setup.…”

Section: Discussionmentioning

confidence: 99%

Topological transitions in an oscillatory driven liquid crystal cell

Clerc

¹

,

Kowalczyk

²

,

Zambra

³

2020

Sci Rep

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Matter under different equilibrium conditions of pressure and temperature exhibits different states such as solid, liquid, gas, and plasma. Exotic states of matter, such as Bose–Einstein condensates, superfluidity, chiral magnets, superconductivity, and liquid crystalline blue phases are observed in thermodynamic equilibrium. Rather than being a result of an aggregation of matter, their emergence is due to a change of a topological state of the system. These topological states can persist out of thermodynamics equilibrium. Here we investigate topological states of matter in a system with injection and dissipation of energy by means of oscillatory forcing. In an experiment involving a liquid crystal cell under the influence of a low-frequency oscillatory electric field, we observe a transition from a non-vortex state to a state in which vortices persist, topological transition. Depending on the period and the type of the forcing, the vortices self-organise, forming square lattices, glassy states, and disordered vortex structures. The bifurcation diagram is characterised experimentally. A continuous topological transition is observed for the sawtooth and square forcings. The scenario changes dramatically for sinusoidal forcing where the topological transition is discontinuous, which is accompanied by serial transitions between square and glassy vortex lattices. Based on a stochastic amplitude equation, we recognise the origin of the transition as the balance between stochastic creation and deterministic annihilation of vortices. Numerical simulations show topological transitions and the emergence of square vortex lattice. Our results show that the matter maintained out of equilibrium by means of the temporal modulation of parameters can exhibit exotic states.

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“…As a matter of fact, optical vortices have attracted attention for their diverse photonic applications ranging from optical tweezers [41,42], quantum computation [43], enhancement of astronomical images [44]. In all these applications, optical vortex lattices are always involved and required [45][46][47][48]. These vortex lattices require sophisticated and complex experimental setup.…”

Section: Discussionmentioning

confidence: 99%

Exotic states of matter in an oscillatory driven liquid crystal cell

Clerc,

Kowalczyk,

Zambra

2020

Preprint

0

View full text Add to dashboard Cite

Matter under different equilibrium conditions of pressure and temperature exhibits different states such as solid, liquid, gas, and plasma. Exotic states of matter, such as Bose-Einstein condensates, superfluidity, chiral magnets, superconductivity, and liquid crystalline blue phases are observed in thermodynamic equilibrium. Rather than being a result of an aggregation of matter, their emergence is due to a change of a topological state of the system. Here we investigate topological states of matter in a system with injection and dissipation of energy. In an experiment involving a liquid crystal cell under the influence of a low-frequency oscillatory electric field, we observe a transition from non-vortex state to a state in which vortices persist. Depending on the period and the type of the forcing, the vortices self-organise forming square lattices, glassy states, and disordered vortex structures. Based on a stochastic amplitude equation, we recognise the origin of the transition as the balance between stochastic creation and deterministic annihilation of vortices. Our results show that the matter maintained out of equilibrium by means of the temporal modulation of parameters can exhibit exotic states.

show abstract

Far-field pattern formation by manipulating the topological charges of square-shaped optical vortex lattices

Cited by 23 publications

References 34 publications

Controllable beam reshaping by mixing square-shaped and hexagonal optical vortex lattices

Controllable beam reshaping by mixing square-shaped and hexagonal optical vortex lattices

Topological transitions in an oscillatory driven liquid crystal cell

Exotic states of matter in an oscillatory driven liquid crystal cell

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