Generation of “perfect” vortex of variable size and its effect in angular spectrum of the down-converted photons

Jabir, M. V.; Chaitanya, N. Apurv; Aadhi, A.; Samanta, G. K.

doi:10.1038/srep21877

Cited by 96 publications

(32 citation statements)

References 23 publications

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“…The thickness of the element is engineered to have an azimuthal phase distribution from 0 to 2πl. Using the SPP [30] of phase winding number l 1 and 2, the Gaussian green pump beam is converted into an optical vortex beam of orders l p 1 and 2, respectively, at >95% efficiency. A lens, L3, of focal length, f 150 mm, is used to focus green beam of orders l p 0, 1, and 2, at the center of the nonlinear crystal.…”

Section: Methodsmentioning

confidence: 99%

Controlled switching of orbital angular momentum in an optical parametric oscillator

Aadhi

Samanta

Kumar

et al. 2017

Optica

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Controlled switching of orbital angular momentum (OAM) of light at practical powers over arbitrary wavelength regions can have important implications for future quantum and classical systems. Here we report on a single source of OAM beams based on an optical parametric oscillator (OPO) that can provide all such capabilities. We demonstrate active transfer of OAM modes of any order, jl p j, of pump to the signal and idler in an OPO, to produce jl p j1 different OAM states by controlling the relative cavity losses of the resonated beams. As a proof-of-principle, we show that when pumping with the OAM states jl p j 1 and jl p j 2 for different relative losses of signal and idler, the OPO has two (j1;0i and j0;1i) and three (j2;0i, j1;1i, and j0;2i) output states, respectively. Our findings show that using a suitable loss modulator, one can achieve rapid switching of the OAM mode in OPO output beams in time.

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Section: Methodsmentioning

confidence: 99%

Controlled switching of orbital angular momentum in an optical parametric oscillator

Aadhi

Samanta

Kumar

et al. 2017

Optica

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“…In order to solve the above issue, perfect vortex (PV) beams have been proposed to possess unchanged annular intensity profiles independent of TCs . The PV beams have the same vortex ring radius and beam divergence for different TCs, enabling their special applications in particle manipulation, plasmonic enhancement, optical communication, quantum optics, and laser manufacturing . The PV beam is typically produced from the Fourier transformation of the Bessel–Gauss (BG) beam, by utilizing a series of free‐space bulky optical components including axicon, spiral phase plate, Fourier transform lens, and spatial light modulator.…”

Section: Introductionmentioning

confidence: 99%

Generating Focused 3D Perfect Vortex Beams By Plasmonic Metasurfaces

Zhang

Liu

Gao

et al. 2018

Advanced Optical Materials

149

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from the Fourier transformation of the Bessel-Gauss (BG) beam, [13,14] by utilizing a series of free-space bulky optical components including axicon, spiral phase plate, Fourier transform lens, and spatial light modulator. This fact greatly increases the optical system complexity and also hinders the device integration in OAM-based photonic circuits.Recently, plasmonic metasurfaces made of subwavelength nanoantenna arrays in thin metallic films have provided a powerful and efficient platform for manipulating the intensity, wavefront, and polarization of light beams beyond the diffraction limit. [26,27] In contrast to the bulky optical components with wavelengthdependent phase shift based on optical path difference, in the Pancharatnam-Berry phase optical elements (PBOEs), the PB phase in broadband operation originating from the geometric phase and accompanied polarization conversion is introduced. [28][29][30][31][32][33][34] The PBOE-based metasurfaces have been widely designed for wavefront shaping applications in making on-chip structured beam generators, [35][36][37][38][39][40][41][42][43][44][45] flat lenses, [46][47][48][49] ultrathin wave plates, [50][51][52] and holograms. [53][54][55][56][57] In this work, we present PBOE-based plasmonic metasurfaces made of rectangular-hole nanoantenna arrays as integrated optical beam converters for the direct generation of the focused 3D PV beams, without using bulky optical components, such as axicon, lens, and spatial light modulator. The PB phase profiles encoded on metasurfaces are uniquely designed with the combined phase distributions of axicon, spiral phase plate, and Fourier transform lens. The single ultrathin plasmonic metasurface device with compact area of 50 µm × 50 µm can create 3D PV beam in a long propagation distance and operate in a broad wavelength range from 600 to 1000 nm, which is useful in wavelength-multiplexed OAM-based optical fiber communication. For comparison, the previously demonstrated PB phase element system used to produce PV beams contains three in-sequence metasurface plates with efficient diameters ≥6 mm fabricated in glass boards, with the single operating wavelength at 632.8 nm. [13] It is shown that the obtained PV beams have the almost constant vortex ring radius and the same beam divergence for different TCs. We also demonstrate that the PV beam structures can be easily adjusted by varying several control parameters in the metasurface design including axicon period, lens focal length, and operation wavelength. Furthermore, multiple PV beams with Perfect vortex (PV) beams possessing annular intensity profiles independent of topological charges promise significant advances in particle manipulation, fiber communication, and quantum optics. The PV beam is typically generated from the Fourier transformation of the Bessel-Gauss beam. However, the conventional method to produce PV beams requires a series of bulky optical components, which greatly increases the system complexity and also hinders the photonic device integration. Here, ...

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“…This asymmetry, in the non-paraxial regime for the pump, leads also to the generation of heralded photons described by superpositions of stationary Bessel modes of different orders, as dependent on the azimuthal angle of detection [22]. Meanwhile, in the paraxial regime the spatial structure of the photon pairs is directly inherited from the pump beam as is known from previous works [17][18][19][22][23][24][25].…”

Section: Introductionmentioning

confidence: 68%

Double transverse wave-vector correlations in photon pairs generated by spontaneous parametric down-conversion pumped by Bessel-Gauss beams

et al. 2016

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We present an experimental and theoretical study of type I, frequency-degenerate spontaneous parametric downconversion (SPDC) with a Bessel-Gauss pump in which we include, both, paraxial and non-paraxial pump beam configurations. We present measurements of the SPDC angular spectrum (AS), of the conditional angular spectrum (CAS) of signal-mode single photons as heralded by the detection of an idler photon, and of the transverse wavevector signal-idler correlations (TWC). We show that as the pump is made increasingly non-paraxial the AS acquires a non-concentric double-cone structure, with the CAS shape depending on the azimuthal location of the heralding detector, while the signal-idler wavevector correlation region splits into characteristic doublet stripes, representing as yet unexplored non-trivial, non-local quantum correlations between the signal and idler photons. Our work provides further understanding of SPDC with a particular class of structured pump beams, and we believe that the controlled presence of double wavevector correlations represents an interesting new resource for photon-pair quantum state engineering.

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Generation of “perfect” vortex of variable size and its effect in angular spectrum of the down-converted photons

Cited by 96 publications

References 23 publications

Controlled switching of orbital angular momentum in an optical parametric oscillator

Controlled switching of orbital angular momentum in an optical parametric oscillator

Generating Focused 3D Perfect Vortex Beams By Plasmonic Metasurfaces

Double transverse wave-vector correlations in photon pairs generated by spontaneous parametric down-conversion pumped by Bessel-Gauss beams

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