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Orbital angular momentum (OAM) from lasers holds promise for compact, at-source solutions for applications ranging from imaging to communications. However, conjugate symmetry between circular spin and opposite helicity OAM states (±ℓ) from conventional spin–orbit approaches has meant that complete control of light’s angular momentum from lasers has remained elusive. Here, we report a metasurface-enhanced laser that overcomes this limitation. We demonstrate new high-purity OAM states with quantum numbers reaching ℓ = 100 and non-symmetric vector vortex beams that lase simultaneously on independent OAM states as much as Δℓ = 90 apart, an extreme violation of previous symmetric spin–orbit lasing devices. Our laser conveniently outputs in the visible, producing new OAM states of light as well as all previously reported OAM modes from lasers, offering a compact and power-scalable source that harnesses intracavity structured matter for the creation of arbitrary chiral states of structured light. A metasurface laser generates orbital angular momentum states with quantum numbers reaching ℓ = 100. Simultaneous output vortex beams, with Δℓ as great as 90, are demonstrated in the visible regime.
Metasurface laser and modes a, Illustration of laser cavity with an intracavity nonlinear crystal (KTP), polarizer (Pol) and metasurface (J-plate), excited by an infrared pump (between mirror M1 and the back KTP crystal face), with the green light emerging from the output coupler (OC) mirror. b, Replication of previous SO laser results showing symmetric states of ∣ℓ∣ = ±1 for three orientations of the fast axis of JP1 (red arrows). c, Creation of a new angular momentum state with ℓ1 = 1 and ℓ2 = 5. As θ (J-plate orientation) is varied, the modal spectrum shifts from H,1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left|H,1\right\rangle$$\end{document} (red squares) to V,5\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\left|V,5\right\rangle$$\end{document} (blue circles), in agreement with theory (curves). Insets: the OAM spectrum at different θ. Error bars show standard deviations. d, Creation of an arbitrary vector superposition state of coherently mixed vortices showing five distinct phase singularities (indicated by white circles), in agreement with theory (shown in the inset). All results were taken at an average pump energy of 230 mJ. For b and d, the colour bar shows normalized intensity plotted with a false colour scale of 0 to 1.
Ultrapure OAM lasing modes a, Measured modal spectrum for ℓ = 10, both internal (blue) and external (red) to the laser. ∣cp,ℓ∣2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$|c_{p,{{\ell}}}|^2$$\end{document} is the modal power in the pth radial mode and ℓth\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ell{\rm{th}}$$\end{document} OAM mode. b,c, The corresponding beam intensities are shown for the internal modes (b) and external modes (c). The bottom inset in a shows an enlarged version with experimental data (lollipop bars) and theoretical predictions (solid line). d,e, The same analysis, performed on the ℓ = 100 modes, showing intensity profiles created external (d) and internal (e) to the laser. The colour bar shows normalized intensity plotted with a false colour scale of 0 to 1. f, OAM distribution of external (red lollipops) and laser (blue bars) modes, where ∣cℓ∣² represents the total OAM modal power (summed over all p modes). g, Comparison of the p = 0 mode weightings for the externally generated beams (red lollipops) versus cavity modes (blue bars). The operating pump energy was 315 mJ for all measurements.
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1School of Physics, University of the Witwatersrand, Wits, South Africa. 2Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard
University, Cambridge, MA, USA. 3Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore. 4CSIR
National Laser Centre, Pretoria, South Africa. 5Applied Physics, Vrije Universiteit Brussel, Brussels, Belgium. 6Center for Nanoscale Systems, Harvard
University, Cambridge, MA, USA. 7CNST – Fondazione Istituto Italiano di Tecnologia Via Giovanni Pascoli, Milan, Italy. 8Present address: Molecular
Chirality Research Center, Chiba University, Inage-ku, Chiba, Japan. e-mail:
In recent years it has become possible to tailor light in what is com-
monly referred to as structured light1, suppporting applications
including high-bandwidth optical communication25, access to
high-dimensional quantum states6,7, enhanced resolution in imag-
ing8 and microscopy9 and control of matter by optical trapping and
tweezing10,11. Foremost among the family of structured light fields are
those related to chiral light, which carries spin angular momentum
and orbital angular momentum (OAM)12, the latter characterized
by a helical phase
about the azimuth (ϕ) with helicity .
Driven by the many applications these beams have spurred13, much
attention has been focused on their efficient creation.
Scalar OAM modes are easily created by dynamic phase
approaches14, while geometric phase is a convenient mechanism for
creating vector combinations of spin and OAM1521, forming cylin-
drical vector vortex beams that are rotationally symmetric complex
states of light with an internal intensity null due to a polarization
singularity22. They are conveniently expressed on the higher-order
Poincaré sphere (HOPS)23,24, where the poles are combinations of
left- and right-circular spin angular momentum states (±σ) com-
bined with symmetrical left- and right-helicity OAM states (±).
This vector addition has opened many exciting possibilities for new
applications that exploit chiral control of both spin angular momen-
tum and OAM degrees of freedom of light2527.
An ongoing challenge is to control light’s chirality, spin and
orbital at source2831. So far, advances have been limited, in part due
to fundamental symmetry restrictions when using geometric phase
and topological photonics and in part due to implementation restric-
tions, for example, in regard to the physical size and spatial resolu-
tion of the optical elements. Such advances include the generation
of symmetric OAM states via the geometric phase32,33, as integrated
on-chip devices3440, in organic lasers41 and as fibre lasers42. Despite
these impressive advances, breaking the symmetry of the spin and
orbital states for arbitrary angular momentum control of light
at source has remained elusive. Arbitrary angular momentum con-
trol requires the ability to produce any desired spin–orbital chiral
state of light, including arbitrary, differing and non-symmetric
OAM values coupled to user-defined polarizations, an infinitely
larger set than the special case of symmetric OAM states, allow-
ing access to super-chiral light with high angular momentum. In
contrast, OAM lasers so far have been demonstrated with only
symmetric superpositions of ± and ±σ, which add to a total
angular momentum of zero, and with modest OAM values of up
to = ±10 (ref. 32). However, super-chiral light with high angu-
lar momentum is known to be important in many fundamental
and applied studies, for example, in quantum studies with Bose–
Einstein condensates, remote sensing with structured light, accurate
rotation measurements, metrology of chiral media and for larger
photon information capacity43.
Here, we report a laser with an intracavity metasurface for
control of light’s angular momentum at source. We design custom
metasurfaces for arbitrary OAM coupling to linear polarization
states, including a metasurface with an extreme imbued helicity of
up to = 100. By doing so, we are able to produce new chiral states
of light from a laser, including simultaneous lasing across vastly dif-
fering and non-symmetric OAM values that are up to Δ = 90 apart,
an extreme violation of previous symmetric spin–orbit (SO) lasing
devices, and demonstrate some intriguing lasing phenomena, for
example, vortex splitting inside a laser medium and coherent lasing
across modes with no spatial overlap. By designing a cavity for mode
metamorphosis, our laser is able to generate ultrahigh-purity OAM
modes with orders of magnitude enhanced purity over their exter-
nally created counterparts, which we show with OAM modes up to
= 100. Importantly, the coupling to linear polarization states facili-
tates a compact design with a reduction in complexity and number
of optical elements over previous geometric phase lasers, the latter
of course restricted to only symmetric states. In addition to these
High-purity orbital angular momentum states
from a visible metasurface laser
Hend Sroor1, Yao-Wei Huang 2,3, Bereneice Sephton1, Darryl Naidoo1,4, Adam Vallés 1,8, Vincent Ginis2,5,
Cheng-Wei Qiu 3, Antonio Ambrosio 6,7, Federico Capasso 2 and Andrew Forbes 1 ✉
Orbital angular momentum (OAM) from lasers holds promise for compact, at-source solutions for applications ranging from
imaging to communications. However, conjugate symmetry between circular spin and opposite helicity OAM states (±) from
conventional spin–orbit approaches has meant that complete control of light’s angular momentum from lasers has remained
elusive. Here, we report a metasurface-enhanced laser that overcomes this limitation. We demonstrate new high-purity OAM
states with quantum numbers reaching = 100 and non-symmetric vector vortex beams that lase simultaneously on indepen-
dent OAM states as much as Δ= 90 apart, an extreme violation of previous symmetric spin–orbit lasing devices. Our laser
conveniently outputs in the visible, producing new OAM states of light as well as all previously reported OAM modes from
lasers, offering a compact and power-scalable source that harnesses intracavity structured matter for the creation of arbitrary
chiral states of structured light.
NATURE PHOTONICS | VOL 14 | AUGUST 2020 | 498–503 |
Content courtesy of Springer Nature, terms of use apply. Rights reserved
... [15] Therefore, non-separable classical states, as a useful simulation toolkit, provide an effective platform to perform entanglement-analogy information processing, [16][17][18][19][20][21][22][23][24] such as measurements of optical coherence, [19] exploration quantum-classical boundary, [20] as well as in characterizing quantum channels in free-space communication. [21] To date, most of non-separable states have been generally constructed in two coupled intrinsic DoFs of laser beam, for instance, space-polarization, [25][26][27][28] or space-time. [29][30][31] In particular, the most popular non-separable state is the spin-orbit state, as a combination of spin angular momentum (SAM) and orbital angular momentum (OAM). ...
... [29][30][31] In particular, the most popular non-separable state is the spin-orbit state, as a combination of spin angular momentum (SAM) and orbital angular momentum (OAM). [32] The generation and manipulation techniques are relatively mature, [26,28,33] which enable promising applications in laser processing, [34] information processing [35] and motion detection. [36] Notably, SAM only has two orthogonal eigenstates, which severely limits the dimensional scalability to increase the information capacity. ...
Full-text available
Non-separable states of structured light have the analogous mathematical forms with quantum entanglement, which offer an effective way to simulate quantum process. However, the classical multi-partite non-separable states analogue to multi-particle entanglements can only be controlled by bulky free-space modulation of light through coupling multiple degrees of freedom (DoFs) with orbital angular momentum (OAM) to achieve high dimensionality and other DoFs to emulate multi-parties. In this paper, a scheme is proposed to directly emit multi-partite non-separable states from a simple laser cavity to mimic multi-particle quantum entanglement. Through manipulating three DoFs as OAM, polarization, and wavevector inside a laser cavity, the eight-dimensional (8D) tripartite states and all Greenberger-Horne-Zeilinger (GHZ)-like states can be generated and controlled on demand. In addition, an effective method is proposed to perform state tomography employing convolutional neural network (CNN), for measuring the generated GHZ-like states with highest fidelity up to 95.11%. This work reveals a feasibility of intra-cavity manipulation of high-dimensional multipartite non-separable states, opening a compact device for quantum-classical analogy and paving the path for advanced quantum scenarios.
... Properly designed 2D optical metasurfaces offer an even higher level of control and modification of spatial phases with high transmission efficiency [33][34][35][36]. The generation of propagating vortex beams by optical metasurfaces has been studied theoretically and experimentally [37][38][39]. However, a comprehensive theory and design strategies to generate OV-rich optical interference fields inside thin films and metasurfaces are missing, as well as the understanding of the role OVs can play in the engineering of light absorption in optically-thin absorbers. ...
... Similarly to our OV circularity metric, OV beam mode purity quantifies the degree of the OV power flow deviation from a perfect circle. We find that the OV circulation values in the two optimized structures discussed above are comparable to the values of the OV beam mode purity reported in recent works [32,39,80,81]. ...
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Optical vortices (OVs) have rapidly varying spatial phase and optical energy that circulates around points or lines of zero optical intensity. Manipulation of OVs offers innovative approaches for various fields, such as optical sensing, communication, and imaging. In this work, we demonstrate the correlation between OVs and absorption enhancement in two types of structures. First, we introduce a simple planar one-dimensional (1D) structure that manipulates OVs using two coherent light sources. The structure shows a maximum of 6.05-fold absorption gap depending on the presence of OVs. Even a slight difference in the incidence angle can influence the generation/annihilation of OVs, which implies the high sensitivity of angular light detection. Second, we apply inverse design to optimize two-dimensional (2D) perfect ultrathin absorbers. The optimized free-form structure achieves 99.90 % absorptance, and the fabricable grating structure achieves 97.85 % at 775 nm wavelength. To evaluate OV fields and their contribution to achieving absorption enhancement, we introduce a new parameter, OV circularity. The optimized structures generate numerous OVs with a maximum circularity of 95.37 % (free-form) and 96.14 % (grating), superior to our 1D structure. Our study reveals the role of high-circularity localized OVs in optimizing nano-structured absorbers and devices for optical sensing, optical communication, and many other applications.
... Control of the angular momentum of light has attracted a great deal of attention in photonics. The optical vector vortex is particularly useful for generating different degrees of freedom for spatially distinguishable channels in data transmission [1][2][3][4][5][6][7][8][9][10][11] . Several vortex microlasers have been successfully demonstrated using microring resonators with asymmetric scatterers 3,4 , planar spiral nanostructures 5 , micropillar chains 6 and symmetric photonic-crystal slabs 7,8 . ...
Full-text available
Optical vector vortex beams provide additional degrees of freedom for spatially distinguishable channels in data transmission. Although several coherent light sources carrying a topological singularity have been reported, it remains challenging to develop a general strategy for designing ultra-small, high-quality photonic nanocavities that generate and support optical vortex modes. Here we demonstrate wavelength-scale, low-threshold, vortex and anti-vortex nanolasers in a C5 symmetric optical cavity formed by a topological disclination. Various photonic disclination cavities are designed and analysed using the similarities between tight-binding models and optical simulations. Unique resonant modes are strongly confined in these cavities, which exhibit wavelength-scale mode volumes and retain topological charges in the disclination geometries. In the experiment, the optical vortices of the lasing modes are clearly identified by measuring polarization-resolved images, Stokes parameters and self-interference patterns. Demonstration of vortex nanolasers using our facile design procedure will pave the way towards next-generation optical communication systems.
... In recent years, metasurfaces composed of elements with artificially engineered two-dimensional structures are applied in electromagnetic wave manipulation [17][18][19], which shows an advantage in generating and controlling conical beams. For example, metasurfaces based on resonant structure can generate vector conical beams [6,7] and OAM conical beams [20][21][22][23] in a narrow bandwidth. Moreover, metasurfaces satisfying the Pancharatnam-Berry (PB) phase can introduce a frequency-independent abrupt phase, which can benefit broadband fabrication for circularly polarized (CP) beams [24][25][26]. ...
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Conical beam antenna plays a significant role in providing stable access to satellite signals for moving communication terminals. Although metasurfaces have been used to generate conical beams, most of them can only reflect conical beams with identically distributed and mirror-symmetric phase responses for left-hand circular polarization and right-hand circular polarization, which can hinder the dual-polarization applications of metasurfaces. In this study, a metasurface is designed to independently manipulate dual-polarized excitations in broadband. To achieve the broadband control of conical beams, broadband conditions for both geometric and propagation phases are developed. Differently, metasurface designed in this study consists of three types of distinguishingly shaped elements, which can provide more degree of freedom in dual-polarization broadband design. In addition, a design method is developed for metasurface to generate the cone angle tailorable conical beams. Via fabricating a metasurface following the proposed method, the designed metasurface is verified in theorem, simulation, and experiment that it can generate desired conical beams with tailored divergent angles and phase responses covering a bandwidth from 12.5 GHz to 17 GHz.
... Significant advances in subwavelength technologies, such as photo-or electronic lithography, have made it possible to create solid-state LIDARs [1][2][3], in which the optical properties of light are controlled by metasurfaces-structures consisting of subwavelength elements. Metasurfaces open up new opportunities for implementation of holograms [4], lenses [5], media with anomalous reflection [6,7], lasers [8,9], perfect absorbers with critical coupling [10,11], sensors [12,13] etc. An actively tuned metasurface with control of the phase and amplitude of individual elements ensures the generation of an arbitrarily complex wave front. ...
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The dynamic steering of a beam reflected from a photonic structure supporting Tamm plasmon polariton is demonstrated. The phase and amplitude of the reflected wave are adjusted by modulating the refractive index of a transparent conductive oxide layer by applying a bias voltage. It is shown that the proposed design allows for two-dimensional beam steering by deflecting the light beam along the polar and azimuthal angles.
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Optical lattices have been widely used from classical to quantum physics. The tunable and scalable fabrication of lattices would be of great significance in lattice‐based multipartite applications. This work demonstrates first that a circular Airy beam (CAB), which has the peculiar properties of self‐healing and abrupt autofocusing, can be used to generate two‐dimensional (2D) optical lattices in propagation when encoded by a programmable spatial mask, resulting in the formation of large‐scale and tunable optical lattices with both axis and axial symmetry, and even high‐orbital kaleidoscope shapes. The efficient diffraction of CAB during the spatial crosstalk with the mask enables the realization of tunable lattices with rich periodicity and complexity. The study shows a flexible method to manipulate lattices with large‐scale and versatile structures for potential applications in integrated and scalable optical and photonic devices.
Vortex beams that carry orbital angular moment (OAM) have recently attracted a great amount of research interest, and metasurfaces and planar microcavities have emerged as two prominent, but mostly separated, methods for Si chip-based vortex beam emission. In this work, we demonstrate in numerical simulation for the first time the hybridization of these two existing methods in a Si chip-based passive emitter (i.e., a light coupler). A unique feature of this device is its broken conjugate symmetry, which originates from introducing a metasurface phase gradient along a microring. The broken conjugate symmetry creates a new phenomenon that we refer to as asymmetric vortex beam emission. It allows two opposite input directions to generate two independent sets of OAM values, a capability that has never been reported before in Si chip-based passive emitters. In addition, we have also developed here a new analytical method to extract the OAM spectrum from a vector vortex beam. This analytical method will prove to be useful for vector vortex beam analysis, as mode purity analysis has rarely been reported in literature due to the complexity of the full-vector nature of such beams. This study provides new approaches for both the design and the analysis of integrated vortex beam emission, which could be utilized in many applications such as free-space optical communications and microfluidic particle manipulation.
The polarization state, an intrinsic property of electromagnetic (EM) waves, plays a key role in determining the mechanism of light-matter interactions. Recently, the bulky elements for evaluating polarization states have been miniaturized by using metasurfaces. However, determining arbitrary linear polarization states from vortex beams (VBs) generated by metasurfaces is quite challenging. Here, a general design of all-silicon quasi-periodic arrays based on polarization multiplexing technology is proposed, which can be used for the detection of arbitrary incident linear polarization (LP) state. By embedding independent helical phase profiles in two orthogonal LP channels, the generated interference spot at the predesigned focal plane is resolvable in a proper polarized direction. Benefitting from the establishment of a parametric theoretical model, the evolution of the incident polarization can be determined using key parameters defined on the pixelated focal plane. The proposed method can flexibly determine the polarization state of incident terahertz (THz) waves, which has great potential in remote sensing, high-resolution imaging, and data communication.
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Orbital angular momentum (OAM) carried by helical light beams is an unbounded degree of freedom that offers a promising platform in modern photonics. So far, integrated sources of coherent light carrying OAM are based on resonators whose design imposes a single, non-tailorable chirality of the wavefront (that is, clockwise or counterclockwise vortices). Here we propose and demonstrate the realization of an integrated microlaser where the chirality of the wavefront can be optically controlled. Importantly, the scheme that we use, based on the optical breaking of time-reversal symmetry in a semiconductor microcavity, can be extended to different laser architectures, thus paving the way to the realization of a new generation of OAM microlasers with tunable chirality. Based on optically breaking time-reversal symmetry by spin polarizing a gain medium with a circularly polarized optical pump, an integrated scheme for controlling the chirality of orbital angular momentum lasing is demonstrated.
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Laser light with a Laguerre-Gaussian amplitude distribution is found to have a well-defined orbital an¬gular momentum. An astigmatic optical system may be used to transform a high-order Laguerre-Gaussian mode into a high-order Hermite-Gaussian mode reversibly. An experiment is proposed to measure the mechanical torque induced by the transfer of orbital angular momentum associated with such a transformation.
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This article reviews recent progress leading to the generation of optical vortex beams. After introducing the basics of optical vortex beams and their promising applications, we summarized different approaches for optical vortex generation by discrete components and laser cavities. We place particular emphasis on the recent development of vortex generation by the planar phase plates, which are able to engineer a spiral phasefront via dynamic or geometric phase in nanoscale, and highlight the independent operation of these two different phases which leads to a multifunctional optical vortex beam generation and independent spin-orbit interaction. We also introduced the recent progress on vortex lasing, including vortex beam generation from the output of bulk lasers by modification of conventional laser cavities with phase elements and from integrated on-chip microlasers. Similar approaches are also applied to generate fractional vortex beams carrying fractional topological charge. The advanced technology and approaches on design and nanofabrications enable multiple vortex beams generation from a single device via multiplexing, multicasting, and vortex array, open up opportunities for applications on data processing, information encoding/decoding, communication and parallel data processing, and micromanipulations.
Structured light is derived from the ability to tailor light, usually referring to the spatial control of its amplitude, phase, and polarization. Although a venerable topic that dates back to the very first laser designs, structuring light at the source has seen an explosion in activity over the past decade, fuelled by a modern toolkit that exploits the versatility of diffractive structures, liquid crystals, metasurfaces/metamaterials, and exotic laser geometries, as well as a myriad of applications that range from imaging, microscopy, and laser material processing to optical communication. Here, the recent progress in creating and controlling structured light is reviewed, with particular emphasis on structuring light at the source: structured light lasers. The various design approaches, including pump shaping, cavity geometries, and the use of custom intracavity optical elements, implemented in a variety of lasers from microchip solutions to high‐power fibers are covered in a tutorial style. The history and latest developments in the field are reviewed, elucidating the various structured light patterns that have been created from lasers, including orbital angular momentum and vector states of light. Finally, the present challenges and limitations are highlighted, along with comments on likely future trends. Structured light refers to the ability to tailor light in amplitude, phase, and polarization. Although traditionally performed external to lasers, there is going demand for structured light at the source. The topic of structured light from lasers is reviewed in a tutorial style, highlighting the exciting recent developments in the field.
Non-Hermitian exceptional points (EPs) represent a special type of degeneracy where not only the eigenvalues coalesce, but also the eigenstates tend to collapse on each other. Recent studies have shown that in the presence of an EP, light-matter interactions are profoundly modified, leading to a host of unexpected optical phenomena ranging from enhanced sensitivity to chiral light transport. Here we introduce a family of unidirectional resonators based on a novel type of broadband exceptional points. In active settings, the resulting unidirectionality exhibits resilience to perturbations, thus providing a robust and tunable approach for directly generating beams with distinct orbital angular momenta (OAM). This work could open up new possibilities for manipulating OAM degrees of freedom in applications pertaining to telecommunications and quantum information sciences, while at the same time may expand the notions of non-Hermiticity in the orbital angular momentum space.
Since their first introduction in 2006, q-plates have found a constantly increasing number of uses in diverse contexts, ranging from fundamental research on complex structured light fields to more applicative innovations of established experimental techniques, passing through a variety of other emerging topics, such as, for instance, quantum information protocols based on the angular momentum of light. In this paper, we present a bird’s-eye view of the progress of this technology in recent years and offer some educated guesses on the most likely future developments.
We report on a programmable liquid crystal spatial light modulator enabling independent orbital angular momentum state control on multiple spectral channels. This is done by using electrically controllable “topological pixels" that independently behave as geometric phase micro-optical elements relying on self-engineered liquid crystal defects. These results open interesting opportunities in optical manipulation, sensing, imaging, and communications, as well as information processing. In particular, spectral vortex modulation allows considering singular spatiotemporal shaping of ultrashort pulses which may find applications in many areas such as material processing, spectroscopy, or elementary particles acceleration.
Vector beams, and in particular vector vortex beams, have found many applications in recent times, both as classical fields and as quantum states. While much attention has focused on the creation and detection of scalar optical fields, it is only recently that vector beams have found their place in the modern laboratory. In this review, we outline the fundamental concepts of vector beams, summarise the various approaches to control them in the laboratory, and give a concise overview of the many applications they have spurned.
Artificially engineered geometric phase optical elements may have tunable photonic functionalities owing to their sensitivity to external fields, as is the case for liquid crystal based devices. However, liquid crystal technology combining high-resolution topological ordering with tunable spectral behavior remains elusive. Here, by using a magnetoelectric external stimulus, we create robust and efficient self-engineered liquid crystal geometric phase vortex masks with a broadly tunable operating wavelength, centimeter-size clear aperture, and high-quality topological ordering.
Complex propagation dynamics of higher‐order polarization singularities are investigated within tailored Poincaré beams. Spatial polarization modulation and additional phase vortices of higher strength are combined, evoking polarization singularity splitting, type conversion, creation and annihilation. These phenomena form singularity “explosions” along their longitudinal evolution. These dynamics of propagating customized light fields and embedded singularities are analyzed experimentally and numerically. Furthermore, similarities of polarization singularity explosion and phase vortex unfolding are discussed, exploring fundamental propagation and spatio‐temporal interaction properties of optical singularities.