Optical vortices in nanophotonics

Li, Chenhao; Maier, Stefan A.; Ren, Haoran

doi:10.37188/co.2021-0066

Cited by 4 publications

(1 citation statement)

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“…The intrinsic orbital angular momentum (OAM) possessed by a helical wavefront has a theoretically unbounded set of orthogonal modes that could carry independent information channels. In addition to its fundamental role in light–matter interactions, − OAM offers a promising approach to greatly improving the capacity of optical devices and systems. − OAM multiplexing has thus been exploited to increase the telecommunication bandwidth for both free-space and fiber-optic networks, to enhance the security of quantum entanglement, and to improve the capacity of holograms. ,− To realize OAM multiplexing, three schemes have been developed to sort and detect OAM modes, including mode interference in real space, spatial filtering in momentum space, and log-polar , or Laguerre–Gaussian mode transformation. However, these far-field approaches require a large propagation distance to produce OAM-distinct diffraction patterns, restricting the OAM detection to diffraction-limited optical systems that hinder OAM applications for integrated photonics.…”

Section: Introductionmentioning

confidence: 99%

Orbital-Angular-Momentum-Controlled Hybrid Nanowire Circuit

Ren

Wang

et al. 2021

Nano Lett.

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Plasmonic nanostructures can enable compact multiplexing of the orbital angular momentum (OAM) of light; however, strong dissipation of the highly localized OAM-distinct plasmonic fields in the near-field region hinders on-chip OAM transmission and processing. Superior transmission efficiency is offered by semiconductor nanowires sustaining highly confined optical modes, but only the polarization degree of freedom has been utilized for their selective excitation. Here we demonstrate that incident OAM beams can selectively excite single-crystalline cadmium sulfide (CdS) nanowires through coupling OAM-distinct plasmonic fields into nanowire waveguides for long-distance transportation. This allows us to build an OAM-controlled hybrid nanowire circuit for optical logic operations including AND and OR gates. In addition, this circuit enables the on-chip photoluminescence readout of OAM-encrypted information. Our results open exciting new avenues not only for nanowire photonics to develop OAM-controlled optical switches, logic gates, and modulators but also for OAM photonics to build ultracompact photonic circuits for information processing.

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Section: Introductionmentioning

confidence: 99%

Orbital-Angular-Momentum-Controlled Hybrid Nanowire Circuit

Ren

Wang

et al. 2021

Nano Lett.

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Metasurface Measuring Twisted Light in Turbulence

Dinter

Kühner

et al. 2022

ACS Photonics

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Orbital angular momentum (OAM) of light represents an independent degree of freedom using orthogonal helical modes for optical and quantum multiplexing, offering great potential to transform future ultrahigh-bandwidth information systems. Practical OAM communication systems suffer from turbulence-induced phase distortions to the propagating beams, decreasing the orthogonality of OAM modes through introduced modal crosstalk. To date, optical systems used for measuring OAM orthogonality breakdown in different turbulence conditions are too bulky and slow (e.g., one OAM mode at a time) for any practical use. Here, we demonstrate the use of an ultrathin OAM modesorting metasurface for characterizing the OAM orthogonality breakdown under different turbulence conditions. Our approach allows the measurement of the whole OAM spectrum at the same time. This metasurface exhibits strong OAM selectivity with an average modal crosstalk below −42.4 dB for OAM modes with topological charges ranging from −15 to +15. Our results suggest that higher-order OAM modes are as robust as lower-order modes in particular turbulence environments, paving the way for future practical free-space OAM communications harnessing high-dimensional OAM multiplexing. We demonstrated that a flat optical device with a small form factor can be integrated with practical communication systems for compact, fast, and efficient generation and detection of twisted light.

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Vectorial wavefront holography based on a polarisation-insensitive hologram

Ren¹

2022

J. Opt.

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Polarisation holography generally demands polarisation-sensitive holograms for reconstructing either polarisation-multiplexed holographic images or polarisation-sensitive image channels. To date, polarisation holography is underpinned by the Jones matrix method that uses birefringent holograms, including ultrathin metasurface holograms, limiting the polarisation control to orthogonal polarisation states. Here I introduce a novel concept of vectorial wavefront holography by exploiting the wavefront shaping of a structured vector beam. I will show that a phase hologram can be used to tailor the polarisation interference of a vector beam in momentum space, creating arbitrary polarisation states that include but not limited to the linear, circular, azimuthal, and radial polarisations. This opens an unprecedented opportunity for the multiplexing generation of arbitrary polarisation distributions in a holographic image. The demonstrated vectorial wavefront holography offers flexible polarisation control without using birefringent optical materials, which may find applications in polarisation imaging, holographic encryption, holographic data storage, multi-view displays, holographic Stokesmeter, and polarimetry.

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Optical vortices in nanophotonics

Cited by 4 publications

References 0 publications

Orbital-Angular-Momentum-Controlled Hybrid Nanowire Circuit

Orbital-Angular-Momentum-Controlled Hybrid Nanowire Circuit

Metasurface Measuring Twisted Light in Turbulence

Vectorial wavefront holography based on a polarisation-insensitive hologram

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