Manipulating the Orbital Angular Momentum of Light at the Micron Scale with Nematic Disclinations in a Liquid Crystal Film

Loussert, Charles; Delabre, Ulysse; Brasselet, Étienne

doi:10.1103/physrevlett.111.037802

Cited by 53 publications

(41 citation statements)

References 19 publications

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“…The realization of higher-order masks with even topological charges > 2 [5] that are desirable for future extremely large telescopes [15] is another manufacturing challenge. Since the basic technological bottleneck can be identified as the manmade technology itself, a nature-assisted approach would likely open a novel generation of vortex masks.Various kinds of spontaneously formed nematic liquid crystal topological defects have been previously demonstrated to behave as natural [16,17] or field-induced [18][19][20] vectorial optical vortex generators with even charge | | = 2 and optimal beam shaping characteristics. Optical vortex masks realized without the need for a machining technique have also been obtained from other mesophases such as cholesteric [21] and smectic [22] liquid crystals, but at the expense of efficiency.…”

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Vortex coronagraphy from self-engineered liquid crystal spin-orbit masks

Aleksanyan

Brasselet

2016

Opt. Lett.

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We report on a soft route toward optical vortex coronagraphy based on self-engineered electrically tunable vortex masks made of liquid crystal topological defects. These results suggest that a natureassisted technological approach to the fabrication of complex phase masks could be useful in optical imaging whenever optical phase singularities are at play.The observation of faint objects near a bright source of light is a basic challenge of high-contrast imaging techniques such as the quest for extrasolar planets in astronomical imaging. This has led to the development of instruments called coronagraphs, which combine the high extinction of stellar light and the high transmission of a low-level signal at small angular separation. Stellar coronagraphy was initiated more than 80 years ago when Lyot studied solar corona without an eclipse by selective occultation of sunlight, placing an opaque disk in the focal plane of a telescope [1]. On the other hand, phase mask coronagraphs offer good performance for the observation of point-like sources. An early version consisted of using a disk π-phase mask [2] whose chromatic drawback arising from discrete radial phase step was solved a few years later by incorporating discrete radial [3] or azimuthal [4] phase modulation to the original design. Later on, continuous azimuthal phase ramps improved the approach [5,6] and led to the advent of optical vortex coronagraphy.Vortex coronagraphs rely on the selective peripheral redistribution of on-axis light outside an area of null intensity at the exit pupil plane of the instrument, which is done by placing a spiraling phase mask in the Fourier plane characterized by a complex transmittance of the form exp(i φ), where the charge is an even integer and φ is the usual azimuthal angle in the transverse plane. This enables optimal on-axis rejection of light by placing an iris (called Lyot stop) at the exit pupil plane, while the off-axis weak signal is almost unaffected for an angular separation larger than the diffraction limit [7]. There are two families of optical vortex phase masks that rely on the scalar (phase) and vectorial (polarization degree of freedom) properties of light. The former case refers to the helical shaping of the wavefront from a refractive phase mask, whereas the latter one exploits the polarization properties of space-variant birefringent optical elements. Indeed, inhomogeneous anisotropic phase masks endowed with azimuthal optical axis orientation of the form ψ(φ) = mφ with m half-integer and associated with half-wave birefringent phase retardation lead to a vortex mask of charge = 2σm for incident on-axis circularly polarized light beam with helicity σ = ±1, as originally shown in [8] using form birefringence (subwavelength grating of dielectric materials) and, in [9], using true birefringence.The achromatic features of the vectorial option versus its scalar counterpart [10,11] have eventually led to equip state-of-the-art large instruments such as Keck, Subaru, Hale, Large Binocular Telescope, and Very Larg...

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Vortex coronagraphy from self-engineered liquid crystal spin-orbit masks

Aleksanyan

Brasselet

2016

Opt. Lett.

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“…The interest in the physics of OAM extends beyond the characterization and preparation of light beams with nonzero OAM, and includes such topics as rotational frequency shifts [4,5], detailed analysis of the vortex physics [6], the physics of OAM in second-harmonic generation [7,8], optical solitons with nonzero OAM [9], transfer and conservation of OAM from pump to downconverted beams [10,11], OAM conservation in degenerate four-wave mixing [12], data transmission using OAM multiplexing [13], and quantum optical aspects such as entanglement [14]. In addition, manipulation and creation of OAM states using coherence gratings [15], liquid crystals [16], and metasurfaces [17] has been reported.There is also a vast body of research on exciton polaritons in semiconductor microcavities. Here, being part of the polaritons, otherwise noninteracting photons experience effective interactions through the polaritons' excitonic component.…”

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Optically Controlled Orbital Angular Momentum Generation in a Polaritonic Quantum Fluid

et al. 2017

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Applications of the orbital angular momentum (OAM) of light range from the next generation of optical communication systems to optical imaging and optical manipulation of particles. Here we propose a micron-sized semiconductor source that emits light with predefined OAM pairs. This source is based on a polaritonic quantum fluid. We show how in this system modulational instabilities can be controlled and harnessed for the spontaneous formation of OAM pairs not present in the pump laser source. Once created, the OAM states exhibit exotic flow patterns in the quantum fluid, characterized by generation-annihilation pairs. These can only occur in open systems, not in equilibrium condensates, in contrast to well-established vortex-antivortex pairs. DOI: 10.1103/PhysRevLett.119.113903 The physics of orbital angular momentum (OAM) of light has attracted considerable attention ([1-3] and references therein). The interest in the physics of OAM extends beyond the characterization and preparation of light beams with nonzero OAM, and includes such topics as rotational frequency shifts [4,5], detailed analysis of the vortex physics [6], the physics of OAM in second-harmonic generation [7,8], optical solitons with nonzero OAM [9], transfer and conservation of OAM from pump to downconverted beams [10,11], OAM conservation in degenerate four-wave mixing [12], data transmission using OAM multiplexing [13], and quantum optical aspects such as entanglement [14]. In addition, manipulation and creation of OAM states using coherence gratings [15], liquid crystals [16], and metasurfaces [17] has been reported.There is also a vast body of research on exciton polaritons in semiconductor microcavities. Here, being part of the polaritons, otherwise noninteracting photons experience effective interactions through the polaritons' excitonic component. This combines the advantages of nonlinear systems with the ease of measuring optical beams. Polaritons form a quantum fluid, and prominent examples of observed phenomena include parametric amplification [18] and Bose condensation ([19,20] and references therein). Polaritonic quantum fluids can support vortices [21,22], and it was recently demonstrated that OAM can be transferred to polaritonic Bose-Einstein condensates using chiral polaritonic lenses [23], and that the number of vortices can be controlled by controlling the OAM of the pump beams [24,25].The question remains whether the relatively strong interaction between polaritons can be used to manipulate, in a well-controlled fashion, the orbital and/or spin angular momentum of polaritons (and thus the light field emitted from the cavity). For example, is it possible to use a beam with OAM of m p and create additional OAM contributions, say two components of OAM m 1 and m 2 , and to use the light beam characteristics of frequency and intensity to control m 1 and m 2 ? The fact that rotationally symmetric states can be unstable under sufficiently large interactions is well known, and examples include spatial pattern formation in chemica...

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“…[ 34,35 ] In this work, we design a gold-fork microstructure with binary modulation, which is described by [ 36 ] where p = 2.4 µm is the period of a grating with line/space ratio of 1, l = 2 Light with orbital angular momentum has found novel applications in macro-manipulation, quantum optics, and optical communication, etc. The generation of orbital angular momentum in nonlinear media, such as second harmonic generation and high harmonic generation, is demonstrated using an optical superlattice and a gas medium.…”

Section: Device Confi Gurationmentioning

confidence: 99%

Third Harmonic Generation of Optical Vortices Using Holography‐Based Gold‐Fork Microstructure

Chen

Cai

et al. 2014

Advanced Optical Materials

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down conversion have been used to study soliton propagation, quantum information processing, frequency multiplexing and so on. [ 3 ] Second harmonic generation (SHG) and high harmonic generation of optical vortex have been demonstrated using nonlinear optical crystal, [ 21,22,25 ] and gas medium [ 23,24 ] respectively. It has been shown that the OAM of the harmonic generation depends on the OAM of the pumping laser [21][22][23][24][25] or the phase dislocation of the medium. One of the breakthroughs in this area was made from direct fabricating phase dislocation of optical super lattice through electric fi eld polling in ferroelectric crystal; [ 25 ] the topological charge of the phase dislocation is then involved in the nonlinear optical processes.In this work, we propose to produce the harmonic generations of optical vortices by integrating holography based gold-fork microstructure into polymer thin fi lm with high thirdorder optical nonlinearity. [ 26,27 ] Computer generated holography technique is utilized to design gold-fork microstructure with desired topological charge, which is then fabricated on gold coated quartz substrate using focus ion beam (FIB) technique. Both second and third harmonic generations of optical vortices are experimentally observed in the polymer thin fi lm/gold-fork/ quartz composite device. Compared to the previous work using second-order nonlinear optical super lattice, [ 25,28 ] the integration of microstructured gold-fork into thin fi lm organic medium is very promising in miniaturization of phase dislocation devices, on-chip integration. Results and Discussions Device Confi gurationBased on the principle of hologram, fork diffraction grating has been widely used to generate or detect optical [29][30][31] and electron vortex beams, [ 32,33 ] and this technique becomes more attractive since the invention of spatial light modulators with which more complex vortex beams can be generated just by programming the liquid crystal pixels using computer. [ 34,35 ] In this work, we design a gold-fork microstructure with binary modulation, which is described by [ 36 ] where p = 2.4 µm is the period of a grating with line/space ratio of 1, l = 2 Light with orbital angular momentum has found novel applications in macro-manipulation, quantum optics, and optical communication, etc. The generation of orbital angular momentum in nonlinear media, such as second harmonic generation and high harmonic generation, is demonstrated using an optical superlattice and a gas medium. Here, by combining a gold-fork micro structure with a conjugated polymer thin fi lm with strong nonlinearity, both second-and third-order harmonic generation of vortex beams with orbital angular momentum are created. Compared to the previously reported medium to generate nonlinear optical vortex, this approach brings great advantages in device miniaturization and provides a promising strategy for realizing on-chip nonlinear optical vortex devices.

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Manipulating the Orbital Angular Momentum of Light at the Micron Scale with Nematic Disclinations in a Liquid Crystal Film

Cited by 53 publications

References 19 publications

Vortex coronagraphy from self-engineered liquid crystal spin-orbit masks

Vortex coronagraphy from self-engineered liquid crystal spin-orbit masks

Optically Controlled Orbital Angular Momentum Generation in a Polaritonic Quantum Fluid

Third Harmonic Generation of Optical Vortices Using Holography‐Based Gold‐Fork Microstructure

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