[Show abstract][Hide abstract] ABSTRACT: A slow-light effect based on metamaterial-induced transparency (MIT) possesses great practical applications for integrated photonic devices. However, to date, only very weak slow-light effects have been obtained in metamaterials because of the intrinsic loss of metal. Moreover, no active control of slow-light has been achieved in metamaterials. Here, we report the realization of a giant slow-light effect on an ultrathin metasurface that consists of periodic arrays of gold nanoprism dimers with a thickness of 40 nm sandwiched between a multilayer-graphene micro-sheet/zinc oxide nanoparticle layer and a monolayer graphene/polycrystalline indium tin oxide layer. The strong field confinement of the plasmonic modes associated with the MIT ensures a tremendous reduction in the group velocity around the transparency window. A group index of more than 4 × 103 is achieved, which is one order of magnitude greater than that of previous reports. A large tunable wavelength range of 120 nm is achieved around the center of the transparency window when the pump light intensity is only 1.5 kW cm−2. The response time is as fast as 42.3 ps. These results demonstrate the potential for the realization of various functional integrated photonic devices based on metasurfaces, such as all-optical buffers and all-optical switches.
[Show abstract][Hide abstract] ABSTRACT: Ultralow power and ultrafast all-optical control of a polarization-insensitive metamaterial-induced transparency are realized by X. Y. Hu, Q. H. Gong, and co-workers on page 1141. They adopt gold nanoprism trimers as meta-molecules and use a multilayer-graphene microsheet/polycrystalline ITO composite as a nonlinear medium. This allows the realization of quantum solid chips based on metamaterials, and also a strategy for constructing photonic materials with large nonlinearity and ultrafast response.
[Show abstract][Hide abstract] ABSTRACT: We proposed a novel meta-structure of gold/graphene trimers and realized ultrasfast and ultra-low power all-optical tunable plasmon-induced transparency around 1150 nm. The nonlinear susceptibility of graphene/ITO film was up to 2.90×10-5 esu.
[Show abstract][Hide abstract] ABSTRACT: Nanoscale multichannel filter is realized in plasmonic circuits directly, which consists of four plasmonic nanocavities coupled via a plasmonic waveguide etched in a gold film. The feature device size is only 1.35 μm, which is reduced by five orders of magnitude compared with previous reports. The optical channels are formed by transparency windows of plasmon-induced transparencies. A shift of 45 nm in the central wavelengths of optical channels is obtained when the plasmonic coupled-nanocavities are covered with a 100-nm-thick poly(methyl methacrylate) layer. This work opens up the possibility for the realization of solid quantum chips based on plasmonic circuits.
No preview · Article · Jun 2014 · Applied Physics Letters
[Show abstract][Hide abstract] ABSTRACT: Optical computing opens up the possibility for the realization of ultrahigh-speed and ultrawide-band information processing. Integrated all-optical logic comparator is one of the indispensable core components of optical computing systems. Unfortunately, up to now, no any nanoscale all-optical logic comparator suitable for on-chip integration applications has been realized experimentally. Here, we report a subtle and effective technical solution to circumvent the obstacles of inherent Ohmic losses of metal and limited propagation length of SPPs. A nanoscale all-optical logic comparator suitable for on-chip integration applications is realized in plasmonic circuits directly. The incident single-bit (or dual-bit) logic signals can be compared and the comparison results are endowed with different logic encodings. An ultrabroad operating wavelength range from 700 to 1000 nm, and an ultrahigh output logic-state contrast-ratio of more than 25 dB are realized experimentally. No high power requirement is needed. Though nanoscale SPP light source and the logic comparator device are integrated into the same plasmonic chip, an ultrasmall feature size is maintained. This work not only paves a way for the realization of complex logic device such as adders and multiplier, but also opens up the possibility for realizing quantum solid chips based on plasmonic circuits.
[Show abstract][Hide abstract] ABSTRACT: Multi-color photon sorting is realized on the basis of plasmonic
microcavities etched in a gold film coated with a polyvinyl alcohol
layer. Both wide-band unidirectional surface plasmon polariton launchers
and plasmonic microcavities are integrated on-chip. The physical
mechanism of the multi-color photon sorting function is attributed as
the plasmonic stop bands prohibiting the surface plasmon polariton
propagation in a broad wavelength range, while the plasmonic
microcavities selectively permit several surface plasmon polaritons to
pass, on the basis of the photon tunneling effect. Incident continuous
wave lasers with wavelengths of 800, 840, and 880 nm are separated, and
decoupled from different output ports. The operating wavelength can be
tuned by adjusting the refractive index of the covering polymer layer.
No preview · Article · Jan 2014 · Journal of Optics
[Show abstract][Hide abstract] ABSTRACT: Plasmonic devices and circuits, bridging the gap between integrated photonic
and microelectronic technology, are promising candidates to realize on-chip
ultrawide-band and ultrahigh-speed information processing. Unfortunately, the
wideband surface plasmon source, one of the most important core components of
integrated plasmonic circuits, is still unavailable up to now. This has
seriously restricted the practical applications of plasmonic circuits. Here, we
report an ultrawide-band unidirectional surface plasmon polariton launcher with
high launching efficiency ratio and large extinction ratio, realized by
combining plasmonic bandgap engineering and linear interference effect. This
device offers excellent performances over an ultrabroad wavelength range from
690 to 900 nm, together with a high average launching efficiency ratio of 1.25,
large average extinction ratio of 30 dB, and ultracompact lateral dimension of
less than 4 um. Compared with previous reports, the operating bandwidth is
enlarged 210 folds, while the largest launching efficiency ratio, largest
extinction ratio, and small feature size are maintained simultaneously. This
provides a strategy for constructing on-chip surface plasmon source, and also
paving the way for the study of integrated plasmonic circuits.
Preview · Article · Nov 2013 · Advanced Optical Materials
[Show abstract][Hide abstract] ABSTRACT: Optical computing uses photons as information carriers, opening up the possibility for ultrahigh-speed and ultrawide-band information processing. Integrated all-optical logic devices are indispensible core components of optical computing systems. However, up to now, little experimental progress has been made in nanoscale all-optical logic discriminators, which have the function of discriminating and encoding incident light signals according to wavelength. Here, we report a strategy to realize a nanoscale all-optical logic discriminator based on plasmonic bandgap engineering in a planar plasmonic microstructure. Light signals falling within different operating wavelength ranges are differentiated and endowed with different logic state encodings. Compared with values previously reported, the operating bandwidth is enlarged by one order of magnitude. Also the SPP light source is integrated with the logic device while retaining its ultracompact size. This opens up a way to construct on-chip all-optical information processors and artificial intelligence systems.
[Show abstract][Hide abstract] ABSTRACT: We report an all-optical logic binary encoder based on two asymmetric plasmonic nanogrooves etched in a gold film coated a polyvinyl alcohol layer. The physical mechanism originates from the unique capability of plasmonic nanogrooves in modulating the propagation properties of surface plasmon polaritons. The incident signal lights dropping in different wavelength regions are endowed with different logic state encodings. In such an ultracompact device with a feature size of only 2.4 μm, the coupling of free-space signal lights to surface plasmon polaritons and the on-chip encoding are integrated together, which is much suitable for practical integration applications.
[Show abstract][Hide abstract] ABSTRACT: A ferroelectric hybrid plasmonic waveguide, made of a polycrystal lithium niobate waveguide separated from a gold film by a silicon dioxide isolation layer, is fabricated by use of laser molecular beam epitaxy growth, electron beam evaporation, and focused ion beam etching. Strong subwavelength mode confinement and excellent long-range propagation are achieved simultaneously for the hybrid plasmonic mode. An all-optical logic OR gate is also realized based on the ferroelectric hybrid plasmonic waveguide. This may provide a way for the study of all-optical logic gates and integrated photonic circuits.
[Show abstract][Hide abstract] ABSTRACT: An all-optical tunable nanoscale wavelength-division multiplexing device is realized theoretically based on a plasmonic microstructure, which is composed of a silver film coated with a monolayer colloidal crystal made of cholesteryl iodide-doped polystyrene. The physical mechanism is attributed to the variation of surface plasmon polariton modes and guided modes caused by pump-laser-induced refractive index change of cholesteryl iodide. An up to 90-nm shift in the resonant wavelength of optical channels can be reached under excitation of a 500 mJ/cm2 pump laser. The number of optical channels can be tuned by adjusting the structure parameters of the monolayer colloidal crystal. This may open a new way for the study of integrated photonic devices.
[Show abstract][Hide abstract] ABSTRACT: We report realizations of nanoscale integrated all-optical XNOR, XOR, NOT, and OR logic gates using plasmonic slot waveguides based on linear interference between surface plasmon polariton modes. The miniature device size with lateral dimensions smaller than 5 μm, precisely controlled optical phase difference, and quasi-monochromatic surface plasmon polariton modes excited by a continuous wave 830-nm laser beam ensure a high intensity contrast ratio of 24 dB between the output logic states '1' and '0'. Compared with previous reported results, the intensity contrast ratio is enhanced four-fold whereas the lateral dimension is reduced four-fold. These compact logic devices are stable, robust, free from environmental impact, and much suitable for practical on-chip applications. These also provide a means to construct all-optical logic devices and nanophotonic processors.
[Show abstract][Hide abstract] ABSTRACT: We experimentally realize a nanoscale all-optical diode in a photonic crystal heterostructure with broken spatial inversion symmetry, performing independent of optical nonlinearity. The physical mechanism lies in unique dispersion relations of the photonic crystal and the transition of incident light between different electromagnetic Bloch modes. An ultrahigh transmission contrast of 10(3) order, a large operating bandwidth of over 50 nm, and an ultralow photon intensity of less than 10 kW/cm(2) are reached simultaneously.
[Show abstract][Hide abstract] ABSTRACT: We experimentally realize an all-optical diode in a photonic crystal heterostructure with broken spatial inversion symmetry. The physical mechanism is attributed to bandgaps only for certain wavevectors and the transition between different electromagnetic Bloch modes, without any nonlinearity and high power requirement. An ultralow photon intensity of 50 kW/cm<sup>2</sup> and an ultrahigh transmission contrast of over 10<sup>3</sup> are reached simultaneously. Compared with previous reported all-optical diodes, the operating power is reduced by seven orders of magnitude, while the transmission contrast is enlarged by two orders of magnitude. This approach may open a way for the study of integrated photonic devices.
[Show abstract][Hide abstract] ABSTRACT: We experimentally demonstrate a large third-order nonlinear susceptibility for a nanocomposite made of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] doped with silver nanoprisms at 1,550 nm, achieved based on nonlinearity enhancement associated with strong surface plasmon resonance. The nonlinear refractive index reaches −1.37 × 10−12 m2/W, which is three orders of magnitude larger than that of pure poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]. An ultrafast response time of 18.7 ps is reached using fast energy transfer from excited states of organic molecules to silver nanoprisms. A low-power and ultrafast nanocomposite photonic crystal all-optical switching is also realized.