Formation and morphological transformation of polarization singularities: hunting the monstar

Kumar, Vijay; Philip, Geo M.; Viswanathan, Nirmal K.

doi:10.1088/2040-8978/15/4/044027

Cited by 28 publications

(21 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Yet, the generation of beams bearing isolated C-points (i.e., alone in a light beam) has been limited to these two cases [19][20][21]. The larger class of asymmetric C-points containing orientations evolving nonlinearly have been produced only in speckle patterns [6][7][8][9], or as C-point pairs (dipoles) in tailored beams [22].The two symmetric cases are the ends of a spectrum of C-points where the pattern of orientations in the ellipse field is nonlinear and asymmetric. Within asymmetric C-points is a hybrid type of C-point, the monstar, which has features of both lemons and stars.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Generation of isolated asymmetric umbilics in light's polarization

et al. 2014

Self Cite

View full text Add to dashboard Cite

Polarization-singularity C-points, a form of line singularities, are the vectorial counterparts of the optical vortices of spatial modes and fundamental optical features of polarization-spatial modes. Their generation in tailored beams has been limited to lemon and star C-points that contain symmetric dislocations in state-of-polarization patterns. In this article we present the theory and laboratory measurements of two complementary methods to generate isolated asymmetric C-points in tailored beams, of which symmetric lemons and stars are limiting cases; and we report on the generation of monstars, an asymmetric C-point with characteristics of both lemons and stars. So far, the study of line singularities relies on the diagnosis of natural occurrences. Non-separable superpositions of polarization and spatial mode of light can provide a vehicle for deliberately creating line-singularity patterns for their study. This polarization-spatial-mode hybridization also adds a new dimension to imaging, where polarization provides additional sensing information [10,11]. Different species exploit polarization-spatial combinations for their survival [12], and line singularities may provide the means to characterize them. At the quantum level, these hybrid modes provide larger Hilbert spaces for encoding information [13]. An investigation of polarization-spatial light modes is also essential for understanding this type of imaging at a deeper level [14].C-points are the umbilical points of the line singularities in the polarization of light because they connect the apex of two opposite cones (a diabolo): of semi-major and semi-minor axis lengths [2,15]. They consist of a state of circular polarization surrounded by a field of polarization ellipses in the optical field, with orientations that rotate about the C-point [16]. C-points are singular points of ellipse orientation. They are intimately linked to the optical vortices of scalar fields, but encode the optical dislocations in the state of polarization instead of the phase [17]. The production of the full spectrum of C-points is of interest in its own right, as it reveals a new domain of complex light not investigated before. The production and analysis of C-points are the basis for new techniques to produce and diagnose optical vortices, which are of interest in metrology due to their high sensitivity to perturbations [18].The two symmetric types of C-point singularities, known as lemons and stars, correspond to dislocations where the ellipse orientation varies linearly with and counter to the angle about the singularity, respectively. Yet, the generation of beams bearing isolated C-points (i.e., alone in a light beam) has been limited to these two cases [19][20][21]. The larger class of asymmetric C-points containing orientations evolving nonlinearly have been produced only in speckle patterns [6][7][8][9], or as C-point pairs (dipoles) in tailored beams [22].The two symmetric cases are the ends of a spectrum of C-points where the pattern of orientations in the ellipse f...

show abstract

mentioning

confidence: 99%

“…These images were used to find the Stokes parameters for each pixel of the imaged beam, and thus the complete state of polarization [22,24].…”

mentioning

confidence: 99%

Generation of isolated asymmetric umbilics in light's polarization

et al. 2014

Self Cite

View full text Add to dashboard Cite

show abstract

“…For example, for the case of I C = +1/2 the lemon has one radial line, but the monstar with the same index has 3 radial lines. Monstars have been produced only by superposition [5,[29][30][31]. Asymmetric polarization disclinations in random speckle fields are ubiquitous, of which 5% are monstars [27,[32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Monstar polarization singularities with elliptically-symmetric q-plates

Cvarch¹,

Khajavi²,

Jones³

et al. 2017

Opt. Express

View full text Add to dashboard Cite

Space-variant polarization patterns present in the transverse mode of optical beams highlight disclination patterns of polarization about a singularity, often a C-point. These patterns are important for understanding rotational dislocations and for characterizing complex polarization patterns. Liquid-crystal devices known as q-plates have been used to produce two of the three types of disclination patterns in optical beams: lemons and stars. Here we report the production of the third type of disclination, which is asymmetric, known as the monstar. We do so with elliptically-symmetric q-plates. We present theory and measurements, and find excellent agreement between the two.

show abstract

“…The singular point in the dislocation is also known as the C-point [2]. Experimentally, these beams can be produced either by superposition [1,[3][4][5][6][7][8][9]; or by passage through optical elements: spatially variable birefringent plates [10], liquidcrystals with spatially variable birefringence [11][12][13], optical elements with stress birefringence [14], optical fibers [15][16][17], or subwavelength gratings [18]. These beams are increasingly finding applications in classical communications [19] and in quantum information [20].…”

Section: Introductionmentioning

confidence: 99%

“…They are characterized by their index I C , denoting the rotation of the disinclination per circulation around the singularity. They have been studied widely in speckle fields produced by nonlinear [24,25] and inhomogeneous media [26,27], but not until recently have monstars, purely asymmetric patterns, been realized in the laboratory using designer optical beams [6,7]. Most of these demonstrations have involved first-order singularities: =  I 1 2 C , or half-turn per circulation about the singularity.…”

Section: Introductionmentioning

confidence: 99%

High-order disclinations in space-variant polarization

Khajavi

Galvez

2016

J. Opt.

View full text Add to dashboard Cite

We present the investigation of high-order disinclination patterns in the spatially variable polarization of a light beam. The beam was prepared by encoding two distinct high-order optical vortices on each of the circular polarization components of the beam. As a consequence, we were able to produce high-index lemon and star patterns, which have positive and negative indices, respectively. By varying the asymmetry of one of the vortices we were able to transform one symmetric pattern (lemon or star) into another (lemon or star). With one exception, monstar patterns always appear for specific ranges of asymmetry regardless of the end symmetric patterns. Mapping of all disclinations within each case is contained in a spherical space, where monstar regions are cusp-shaped. We found that high-order monstar patterns can have positive or negative index.

show abstract

Formation and morphological transformation of polarization singularities: hunting the monstar

Cited by 28 publications

References 20 publications

Generation of isolated asymmetric umbilics in light's polarization

Generation of isolated asymmetric umbilics in light's polarization

Monstar polarization singularities with elliptically-symmetric q-plates

High-order disclinations in space-variant polarization

Contact Info

Product

Resources

About