1.7 Gbit/in.2 gray-scale continuous-phase-change femtosecond image storage

Wang, Qian; Maddock, Jonathan; Rogers, Edward T. F.; Roy, Tapashree; Craig, Christopher; MacDonald, Kevin F.; Hewak, D.W.; Zheludev, Nikolay I.

doi:10.1063/1.4869575

Cited by 60 publications

(50 citation statements)

References 20 publications

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“…The latter can also be achieved through an accumulation of sub-threshold (including fs laser pulse) excitations, facilitating reproducible "greyscale" and neuromorphic switching modes of interest for all-optical data and image processing, and harnessed recently for direct, reversible laser writing of planar optical elements and short/mid-wave IR metamaterials in a chalcogenide thin film. [23][24][25][26] Here, we demonstrate structurally engineered highquality near-infrared transmission and reflection resonances in planar (300 nm thick) dielectric nano-grating metasurfaces of amorphous germanium antimony telluride (Ge 2 Sb 2 Te 5 or GST -a widely used composition in data storage applications), and the non-volatile switching of these resonances via laser-induced crystallization of the chalcogenide. We employ nano-grating array metasurface patterns of subwavelength periodicity ( Fig.…”

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confidence: 99%

All-dielectric phase-change reconfigurable metasurface

Karvounis

Gholipour

MacDonald

et al. 2016

Applied Physics Letters

246

183

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We harness non-volatile, amorphous-crystalline transitions in the chalcogenide phase-change medium germanium antimony telluride (GST) to realize optically-switchable, all-dielectric metamaterials. Nanostructured, subwavelength-thickness films of GST present high-quality resonances that are spectrally shifted by laser-induced structural transitions, providing reflectivity and transmission switching contrast ratios of up to 5:1 (7 dB) at visible/near-infrared wavelengths selected by design.Comment: 8 pages, 8 figure

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mentioning

confidence: 99%

All-dielectric phase-change reconfigurable metasurface

Karvounis

Gholipour

MacDonald

et al. 2016

Applied Physics Letters

246

183

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“…When annealed to a temperature between the glass-transition and the melting point, the GST transforms from an amorphous state into a metastable cubic crystalline state, while a short high-density laser pulse melts and quickly quenches the material back to its amorphous phase with a pronounced contrast of dielectric properties observed between the two phases. Although nanosecond and microsecond laser pulses, which provide robust switching between amorphous and crystalline phases, are conventionally used in optical data storage technology, it was recently shown that femtosecond laser pulses can induce multi-level switching 29,30 . In the multi-level regime, metastable semi-crystallized states are created by carefully controlling the energy and the number of stimulating optical pulses.…”

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confidence: 99%

Optically reconfigurable metasurfaces and photonic devices based on phase change materials

et al. 2015

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Photonic components with adjustable parameters, such as variable-focal-length lenses or spectral filters, that can change functionality upon optical stimulation, could offer numerous useful applications. Tuning of such components is conventionally achieved by either micro-or nano-mechanical actuation of their constitutive parts, by stretching or heating. Here we report a new type of dielectric metasurface for making reconfigurable optical components that are created with light in a non-volatile and reversible fashion. Such components are written, erased and re-written as two-dimensional binary or grey-scale patterns into a nanoscale film of phase change material by inducing a refractive-index-changing phase-transition with tailored trains of femtosecond pulses. We combine germanium-antimony-tellurium-based films with a sub-wavelength-resolution optical writing process to demonstrate a variety of devices: visible-range reconfigurable bi-chromatic and multi-focus Fresnel zone-plates, a super-oscillatory lens with sub-wavelength focus, a grey-scale hologram and a dielectric metamaterial with on-demand reflection and transmission resonances.A metasurface made of carefully designed discrete metallic or dielectric elements can exhibit interesting abilities for directing the flow of electromagnetic radiation across the entire electromagnetic spectrum with similar capabilities to planar holograms in optics 1,2,3,4,5,6,7,8,9,10 . As substantial efforts are now focused on developing metamaterials with switchable 11, 12 and reconfigurable metadevices 13 driven by thermal 14,15 , electrostatic 16 and magnetic forces 17,18 and stretching 19 , and we are witnessing the emergence of concepts of randomly accessible reconfigurable metamaterials in the microwave 20,21,22 and optical regions of the spectrum 23, 24 thus making reconfigurable photonic devices 2 controllable by external signals a realistic possibility. Here we introduce and demonstrate dynamic photonic components written into a dielectric film that can be randomly and reversibly reconfigured with light. Recent work demonstrated control of a metamaterial with light 25 . In contrast, the technique reported here allows random and non-volatile two-dimensional control of optical properties of the film with diffraction-limited resolution and in a femtosecond (fs) time-frame. This provides much more flexibility and allows the creation of various photonic functions difficult or impossible with the above mentioned technologies. The randomly reconfigurable metasurface uses phase-change material and is written, erased and re-written as a two-dimensional binary or grey-scale pattern into a nanoscale thin film by inducing a refractive-index-changing phase-transition with tailored trains of femtosecond pulses.We use phase-change medium, the chalcogenide compound Ge 2 Sb 2 Te 5 (GST), which is widely exploited in rewritable optical disk storage technology and non-volatile electronic memories due to its good thermal stability, high switching speed and large number of achievable rewr...

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“…A 730 nm, 75 fs pulse train was reduced to 1 MHz frequency using an electro-optical modulator and focused onto a GST film. To write a pattern in the GST, a low pulse energy was used to heat the film below the melting point but above the glasstransition temperature and thus gradually crystallize it 13 . The size and contrast of crystallized mark can be precisely controlled by selecting the pulse energy and number of pulses used.…”

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

“…The size and contrast of crystallized mark can be precisely controlled by selecting the pulse energy and number of pulses used. To erase the mark, a single high-energy pulse was applied to have the GST mark melted and cooled rapidly to form the amorphous phase 13 .…”

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

Reconfigurable phase-change photomask for grayscale photolithography

Wang

Yuan

Kiang

et al. 2017

Applied Physics Letters

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We demonstrate a grayscale photolithography technique which uses a thin phase-change film as a photomask to locally control the exposure dose and allows three-dimensional (3D) sculpting photoresist for the manufacture of 3D structures. Unlike traditional photomasks, the transmission of the phase-change material photomask can be set to an arbitrary gray level with submicron lateral resolution, and the mask pattern can be optically reconfigured on demand, by inducing a refractiveindex-changing phase-transition with femtosecond laser pulses. We show a spiral phase plate and a phase-type super-oscillatory lens fabricated on Si wafers to demonstrate the range of applications that can be addressed with this technique.

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1.7 Gbit/in.2 gray-scale continuous-phase-change femtosecond image storage

Abstract: Articles you may be interested inPhase change behaviors of Zn-doped Ge2Sb2Te5 films Appl.

Cited by 60 publications

References 20 publications

All-dielectric phase-change reconfigurable metasurface

All-dielectric phase-change reconfigurable metasurface

Optically reconfigurable metasurfaces and photonic devices based on phase change materials

Reconfigurable phase-change photomask for grayscale photolithography

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