Screw Dislocations in Light Wavefronts

Bazhenov, V. Yu.; Soskin, M. S.; Vasnetsov, M. V.

doi:10.1080/09500349214551011

Cited by 360 publications

(169 citation statements)

References 5 publications

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“…Originally found and described for sound waves (Nye & Berry 1974), they have also been described for such unrelated phenomena as sea tides (Berry 1981). Dislocations became part of mainstream physics when they were found in light associated with laser beams carrying intrinsic angular momentum (Harris et al 1994;Allen et al 1992;Bazhenov et al 1992). López Ariste et al (2013) showed that waves carrying dislocations were solutions of the basic MHD wave equation and that, in particular, the kink mode carries a vortex dislocation in its geometrical axis (Fig.…”

Section: Introductionmentioning

confidence: 99%

Vortex waves in sunspots

Ariste

Centeno

Khomenko

2016

A&A

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Context. Waves in the magnetized solar atmosphere are one of the favourite means of transferring and depositing energy into the solar corona. The study of waves brings information not just on the dynamics of the magnetized plasma, but also on the possible ways in which the corona is heated. Aims. The identification and analysis of the phase singularities or dislocations provide us with a complementary approach to the magnetoacoustic and Aflvén waves propagating in the solar atmosphere. They allow us to identify individual wave modes, shedding light on the probability of excitation or the nature of the triggering mechanism. Methods. We use a time series of Doppler shifts measured in two spectral lines, filtered around the three-minute period region. The data show a propagating magnetoacoustic slow mode with several dislocations and, in particular, a vortex line. We study under what conditions the different wave modes propagating in the umbra can generate the observed dislocations. Results. The observed dislocations can be fully interpreted as a sequence of sausage and kink modes excited sequentially on average during 15 min. Kink and sausage modes appear to be excited independently and sequentially. The transition from one to the other lasts less than three minutes. During the transition we observe and model the appearance of superoscillations inducing large phase gradients and phase mixing. Conclusions. The analysis of the observed wave dislocations leads us to the identification of the propagating wave modes in umbrae. The identification in the data of superoscillatory regions during the transition from one mode to the other may be an important indicator of the location of wave dissipation.

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Section: Introductionmentioning

confidence: 99%

Vortex waves in sunspots

Ariste

Centeno

Khomenko

2016

A&A

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“…At the intensity null point, the phase is undefined and in its neighborhood, the wavefront is helical in shape [2,3]. The topology is such that all the wavefronts which are disconnected and separated by distance k with each other in an otherwise non-singular beam, become connected thereby forming a single wavefront filling the entire space.…”

Section: Introductionmentioning

confidence: 99%

Singularities in cylindrical vector beams

Verma

Pal

Joshi

et al. 2015

Journal of Modern Optics

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Cylindrical vector beams with azimuthal and radial polarization distributions are studied for singularities. It is shown experimentally that these beams have screw dislocation as well as edge dislocation at the same time. The relation between phase and polarization of light beam is the key to understand this fact. We envisage that this has potential application in phase synthesis using polarization engineering. Further, the polarization singularities in these inhomogeneously polarized beams are examined by measuring Stokes parameters across the cross-section of these beams.

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“…Indeed, under special conditions, the interaction between vortices of this type resembles that of their fluid counterparts [2]. Although the existence of a wavefront with screw dislocation was first identified acoustically, most of the subsequent research and applications has been reported in the optics field [3]. In this sense, it has been demonstrated that a helical wavefront transports angular moment [4], which makes it possible to control the orientation of absorbent particles in an optical tweezer [5].…”

Section: Introduction P Hase Distribution Singularities Constitutementioning

confidence: 99%

Airborne ultrasonic vortex generation using flexible ferroelectrets

Ealo

Prieto

Seco

2011

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Abstract-Cellular ferroelectrets exhibit interesting electromechanical-acoustical characteristics. Their recent appearance and remarkable properties open up new possibilities for the design and development of ultrasonic transducers. In particular, the feasibility of fabricating ultrasonic vortex generators using ferroelectret films is demonstrated in this work. To this end, a transducer prototype was built by gluing the material onto a tangential-helical surface (outer diameter: 40 mm, pitch: 3.45 mm). Experimental results agree well with the theoretical estimation of the pressure and phase of the acoustic field in the near field and far field, which corroborates the potential of ferroelectrets to customize special acoustic fields. Furthermore, the proposed fabrication procedure is inexpensive and represents a new alternative for exploring and analyzing the special characteristics of acoustical helical wavefronts.

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Screw Dislocations in Light Wavefronts

Cited by 360 publications

References 5 publications

Vortex waves in sunspots

Vortex waves in sunspots

Singularities in cylindrical vector beams

Airborne ultrasonic vortex generation using flexible ferroelectrets

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