Optics of light beams with screw dislocations

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

doi:10.1016/0030-4018(93)90168-5

Cited by 367 publications

(198 citation statements)

References 10 publications

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“…The self-focusing action of the nonlinearity compensated by diffraction results in self-sustained bright spatial solitons [12], which can exist as isolated states or form complex ensembles, sometimes interacting in a particle-like fashion [169][170][171][172][173][174][175]. Also, dark solitons [176][177][178][179][180][181][182][183][184] and optical vortices [185][186][187][188][189][190][191][192][193][194][195][196] have been described and experimentally observed. In such a mirrorless configuration feedback is absent, and one obtains not a spontaneous pattern formation, but just a nonlinear transformation of the input distribution.…”

Section: Mirrorless Configurationmentioning

confidence: 99%

Transverse Patterns in Nonlinear Optical Resonators

Staliūnas

Sánchez‐Morcillo

2003

Springer Tracts in Modern Physics

172

156

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This book is devoted to the formation and dynamics of localized structures (vortices, solitons) and of extended patterns (stripes, hexagons, tilted waves) in nonlinear optical resonators such as lasers, optical parametric oscillators, and photorefractive oscillators. Theoretical analysis is performed by deriving order parameter equations, and also through numerical integration of microscopic models of the systems under investigation. Experimental observations, and possible technological implementations of transverse optical patterns are also discussed. A comparison with patterns found in other nonlinear systems, i.e. chemical, biological, and hydrodynamical systems, is given.

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Section: Mirrorless Configurationmentioning

confidence: 99%

Transverse Patterns in Nonlinear Optical Resonators

Staliūnas

Sánchez‐Morcillo

2003

Springer Tracts in Modern Physics

172

156

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“…The most remarkable observation is that the singularity can survive the highly nonlinear process of HHG, even though strong ionization takes place 25 . Apart from the already known possibility of second-harmonic generation and four-wave mixing 26,27 , another field of nonlinear interaction with beams having an angular momentum is added by this research. The observed structure is not a perfect optical vortex yet, owing to azimuthal instabilities and decay taking place in the generation process.…”

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confidence: 99%

Strong-field physics with singular light beams

et al. 2012

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Light beams carrying a point singularity with a screw-type phase distribution are associated with an optical vortex. The corresponding momentum flow leads to an orbital angular momentum of the photons 1-3 . The study of optical vortices has led to applications such as particle micro-manipulation 4,5 , imaging 6 , interferometry 7 , quantum information 8 and highresolution microscopy and lithography 9 . Recent analyses showed that transitions forbidden by selection rules seem to be allowed when using optical vortex beams 10 . To exploit these intriguing new applications, it is often necessary to shorten the wavelength by nonlinear frequency conversion. However, during the conversion the optical vortices tend to break up 11-13 . Here we show that optical vortices can be generated in the extreme ultraviolet (XUV) region using high-harmonic generation 14,15 . The singularity impressed on the fundamental beam survives the highly nonlinear process. Vortices in the XUV region have the same phase distribution as the driving field, which is in contradiction to previous findings 16 , where multiplication of the momentum by the harmonic order is expected. This approach opens the way for several applications based on vortex beams in the XUV region.Places where physical quantities become infinite or change abruptly are called singularities. The presence of phase dislocations (singularities) in the wavefront of a light beam determines both the phase and intensity structure around them. As the phase becomes indeterminate at singularities, both the real and the imaginary parts of the field amplitude (that is, also the field intensity) vanish. The characteristic helical phase profiles of optical vortices are described by exp(imθ) multipliers, where θ is the azimuthal coordinate and the integer number m is their topological charge, also called dislocation strength or winding number.Recalling the fact that in free space the Poynting vector gives the momentum flow, for helical phase fronts the Poynting vector has an azimuthal component that produces an orbital angular momentum parallel to the axis of the beam. The momentum circulates around the beam axis, so such beams are said to contain an optical vortex. As has been shown 1-3 , an m-fold charged optical vortex beam carries an orbital angular momentum of mh per photon independent of the spin angular momentum (that is, the polarization state). It was shown that transitions that are forbidden by known selection rules in the electric and magnetic dipole approximation seem to be allowed when using optical vortex beams 10 . This provides a new degree of freedom in the spectroscopy of forbidden transitions. Multi-coloured optical vortices can be generated through a nonlinear frequency-conversion process such as second-harmonic generation 16 or four-wave mixing, which is an important process in the white-light vortex generation. However, as predicted in ref. 11 and observed in ref. 12, vortex breakup in self-focusing nonlinear media is an important issue for supercontinuum vortex genera...

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“…In the case of un-seeded geometries (i.e., no SH input light), and in absence of Poynting vector walk-off between the FF and SH beams, sum-and difference-charge arithmetic operations have been predicted and observed experimentally. [2][3][4] However, a new range of phenomena is discovered in seeded geometries and with Poynting vector walk-off. In particular, in the case of seeded schemes without walk-off, our numerical and experimental investigations show the spontaneous nucleation of multiple-vortex twins.…”

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confidence: 99%

Vortex nucleation and evolution in parametric wave mixing

Molina‐Terriza

Torner²

1999 IEEE LEOS Annual Meeting Conference Proceedings. LEOS'99. 12th Annual Meeting. IEEE Lasers and Electro-Optics Society 1999

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SPAINSingular light beams, that contain topological wave front dislocations are ubiquitous entities that display fascinating properties with widespread important applications. I Screw dislocations, or vortices, are a common dislocation type. They are spiral phase-ramps around a singularity where the phase of the wave is undefined and its amplitude vanishes. The order of the screw dislocation multiplied by its sign is referred to as the winding number, or topological charge of the dislocation. Vortices appear spontaneously in several settings, including in speckle-fields, in optical cavities and in the doughnut laser modes, and otherwise they can be generated with phase masks, or with astigmatic optical components. Vortices also form by self-wave front modulation in nonlinear optical media. In this context, parametric wave mixing of multiple waves propagating in quadratic nonlinear media constitutes a fascinating scenario. In this paper we predict a variety of new phenomena, that includes the spontaneous nucleation of multiple vortex twins, vortex rotation and drift, vortex-antivortex interaction and annihilation, and formation of quasi-aligned patterns of single-charge vortices.We consider cw light propagation in a bulk quadratic nonlinear crystal under conditions for type 1 second-harmonic generation. We restrict ourselves to up-conversion geometries with material and light conditions that yield negligible depletion of the pump fundamental frequency (FF) beam. Then, the second-harmonic (SH) beam is dictated by an inhomogeneous linear partial differential equation whose general solution can be obtained by means of the Green function approach. In the case of un-seeded geometries (i.e., no SH input light), and in absence of Poynting vector walk-off between the FF and SH beams, sum-and difference-charge arithmetic operations have been predicted and observed experimentally. 2-4 However, a new range of phenomena is discovered in seeded geometries and with Poynting vector walk-off. In particular, in the case of seeded schemes without walk-off, our numerical and experimental investigations show the spontaneous nucleation of multiple-vortex twins. In such case, the number of vortices present in the SH beam and its total topological charge varies with the propagation distance inside the crystal. Figure 1 shows a typical example of the vortex pattern that is typically obtained. Walk-off introduces a new range of phenomena. In the case of un-seeded schemes with a Gaussian pump beam with a single-charge vortex nested, one finds that the generated SH beam is given by the expression Here the transverse coordinates are normalized to the FF beam width q, and the propagation coordinate 6 is normalized to twice the diffraction length of the FF beam Ldl=k1q2/2. The parameter p is given by P=klq2Ak, where Ak=2kl-k2 is the

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Optics of light beams with screw dislocations

Cited by 367 publications

References 10 publications

Transverse Patterns in Nonlinear Optical Resonators

Transverse Patterns in Nonlinear Optical Resonators

Strong-field physics with singular light beams

Vortex nucleation and evolution in parametric wave mixing

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