Subwavelength modulational instability and plasmon oscillons in nanoparticle arrays

We study modulational instability in nonlinear arrays of subwavelength metallic nanoparticles, and analyze numerically nonlinear scenarios of the instability development. We demonstrate that modulational instability can lead to the formation of regular periodic or quasi-periodic modulations of the polarization. We reveal that such nonlinear nanoparticle arrays can support long-lived standing and moving oscillating nonlinear localized modes - plasmon oscillons.Comment: 5 pages, 5 figures, published in Physical Review Letter

Subwavelength plasmonic kinks in arrays of metallic nanoparticles

We analyze nonlinear effects in optically driven arrays of nonlinear metallic nanoparticles. We demonstrate that such plasmonic systems are characterized by a bistable response, and they can support the propagation of dissipative switching waves (or plasmonic kinks) connecting the states with different polarization. We study numerically the properties of such plasmonic kinks which are characterized by a subwavelength extent and a tunable velocity.Comment: 6 pages, 5 figures, published in Opt. Expres

Birefringent left-handed metamaterials and perfect lenses

We describe the properties of birefringent left-handed metamaterials and introduce the concept of a birefringent perfect lens. We demonstrate that, in a sharp contrast to the conventional left-handed perfect lens at $\epsilon=\mu=-1$, where $\epsilon$ is the dielectric constant and $\mu$ is the magnetic permeability, the birefringent left-handed lens can focus either TE or TM polarized waves or both of them, allowing a spatial separation of the TE and TM images. We discuss several applications of the birefringent left-handed lenses such as the beam splitting and near-field diagnostics at the sub-wavelength scale.Comment: 4 pages 6 figure

Ultrafast cryptography with indefinitely switchable optical nanoantennas

Bistability is widely exploited to demonstrate all-optical signal processing and light-based computing. The standard paradigm of switching between two steady states corresponding to '0" and '1" bits is based on the rule that a transition occurs when the signal pulse intensity overcomes the bistability threshold, and otherwise, the system remains in the initial state. Here, we break with this concept by revealing the phenomenon of indefinite switching in which the eventual steady state of a resonant bistable system is transformed into a nontrivial function of signal pulse parameters for moderately intense signal pulses. The essential nonlinearity of the indefinite switching allows realization of well-protected cryptographic algorithms with a single bistable element in contrast to software-assisted cryptographic protocols that require thousands of logic gates. As a proof of concept, we demonstrate stream deciphering of the word 'enigma' by means of an indefinitely switchable optical nanoantenna. An extremely high bitrate ranging from ~0.1 to 1 terabits per second and a small size make such systems promising as basic elements for all-optical cryptographic architectures.Comment: Light: Science & Applications, to appea

Penentuan Status Hara Nitrogen pada Bibit Duku

Nitrogen merupakan unsur yang sangat memengaruhi pertumbuhan, perkembangan dan produksi tanaman. Hara ini merupakan komponen esensial klorofil, protein, hormon, dan enzim. Gejala kekurangan atau kelebihan hara tersebut dapat terdeteksi secara visual pada penampilan daun, sehingga sangat penting untuk mencegah terjadinya kedua kondisi tersebut pada pertumbuhan bibit duku (Lansium domesticum Corr). Penelitian status hara nitrogen dilakukan pada bibit duku umur 2 tahun yang ditanam pada media pasir di Provinsi Jambi dari bulan Maret 2010 sampai dengan Maret 2011. Percobaan disusun menggunakan rancangan acak kelompok, dengan lima perlakuan dosis nitrogen: 0, 100, 200, 400, dan 800 ppm/tanaman, diaplikasikan dalam bentuk air irigasi setiap 2 hari sekali dan masing-masing perlakuan terdiri dari tiga tanaman dan tiga ulangan. Hasil penelitian menunjukkan bahwa gejala kekurangan nitrogen pertama terlihat pada daun tua yang ditandai dengan Perubahan warna daun menjadi hijau kekuningan (klorosis), tangkai daun lemah dan berwarna kuning, jumlah daun kurang atau sama dengan 4,2 helai, pertumbuhan terhambat, dan konsentrasi nitrogen daun kurang dari 1,13%. Kecukupan nitrogen ditandai dengan pertumbuhan yang normal, daun berwarna hijau tua, jumlah daun berkisar antara 5 sampai 5,5 helai dan konsentrasi nitrogen daun antara 1,13 sampai 1,44%. Kelebihan nitrogen terlihat pada daun yang berwarna coklat dan mengalami nekrosis, jumlah daun kurang dari 3,78 helai, pertumbuhan bibit terhambat, konsentrasi nitrogen daun lebih dari 1,44%. Pertumbuhan maksimum membutuhkan 381 ppm pupuk nitrogen/tanaman, yang setara dengan 8 g urea/l air atau 77 g Urea/tahun. Rekomendasi pemupukan N ini merupakan salah satu teknologi yang dapat meningkatkan ketersediaan bibit duku bermutu