Optically monitored nuclear spin dynamics in individual GaAs quantum dots grown by droplet epitaxy

We report optical orientation experiments in individual, strain free GaAs quantum dots in AlGaAs grown by droplet epitaxy. Circularly polarized optical excitation yields strong circular polarization of the resulting photoluminescence at 4K. Optical injection of spin polarized electrons into a dot gives rise to dynamical nuclear polarization that considerably changes the exciton Zeeman splitting (Overhauser shift). We show that the created nuclear polarization is bistable and present a direct measurement of the build-up time of the nuclear polarization in a single GaAs dot in the order of one second.Comment: 7 pages, 3 figure

Large-Area Resonance-Tuned Metasurfaces for On-Demand Enhanced Spectroscopy

We show an effective procedure for lateral structure tuning in nanoimprint lithography (NIL) that has been developed as a vertical top-down method fabricating large-area nanopatterns. The procedure was applied to optical resonance tuning in stacked complementary (SC) metasurfaces based on silicon-on-insulator (SOI) substrates and was found to realize structure tuning at nm precision using only one mold in the NIL process. The structure tuning enabled us to obtain fine tuning of the optical resonances, offering cost-effective, high-throughput, and high-precision nanofabrication. We also demonstrate that the tuned optical resonances selectively and significantly enhance fluorescence (FL) of dye molecules in a near-infrared range. FL intensity on a SC metasurface was found to be more than 450-fold larger than the FL intensity on flat Au film on base SOI substrate

Gap deformation and classical wave localization in disordered two-dimensional photonic band gap materials

By using two ab initio numerical methods we study the effects that disorder has on the spectral gaps and on wave localization in two-dimensional photonic band gap materials. We find that there are basically two different responses depending on the lattice realization (solid dielectric cylinders in air or vise versa), the wave polarization, and the particular form under which disorder is introduced. Two different pictures for the photonic states are employed, the ``nearly free'' photon and the ``strongly localized'' photon. These originate from the two different mechanisms responsible for the formation of the spectral gaps, ie. multiple scattering and single scatterer resonances, and they qualitatively explain our results.Comment: Accepted for publication in Phys. Rev.

Highly tunable ultra-narrow-resonances with optical nano-antenna phased arrays in the infrared

We report our recent development in pursuing high Quality-Factor (high-Q factor) plasmonic resonances, with vertically aligned two dimensional (2-D) periodic nanorod arrays. The 2-D vertically aligned nano-antenna array can have high-Q resonances varying arbitrarily from near infrared to terahertz regime, as the antenna resonances of the nanorod are highly tunable through material properties, the length of the nanorod, and the orthogonal polarization direction with respect to the lattice surface,. The high-Q in combination with the small optical mode volume gives a very high Purcell factor, which could potentially be applied to various enhanced nonlinear photonics or optoelectronic devices. The 'hot spots' around the nanorods can be easily harvested as no index-matching is necessary. The resonances maintain their high-Q factor with the change of the environmental refractive index, which is of great interest for molecular sensing.Comment: 8 pages, appears in Proc. SPIE 9163, Plasmonics: Metallic Nanostructures and Their Optical Properties XII, 91630R (September 10, 2014

Single-photon generation from a nitrogen impurity center in GaAs

We have demonstrated single-photon emission from a nitrogen luminescence center in GaAs. An inhomogeneously broadened luminescence band formed by localized centers was observed in the spectral range from 1480 meV to 1510 meV at 5 K in nitrogen delta-doped GaAs. Optical properties of the individual centers were investigated by steady-state and time-resolved micro photoluminescence. We have found that a bright luminescence center emits single photons with a radiative lifetime of 650 ps, which is much shorter than the lifetime of NN pairs in previous reports

Photon correlation in GaAs self-assembled quantum dots

We report on photon coincidence measurement in a single GaAs self-assembled quantum dot (QD) using a pulsed excitation light source. At low excitation, when a neutral exciton line was present in the photoluminescence (PL) spectrum, we observed nearly perfect single photon emission from an isolated QD at 670 nm wavelength. For higher excitation, multiple PL lines appeared on the spectra, reflecting the formation of exciton complexes. Cross-correlation functions between these lines showed either bunching or antibunching behavior, depending on whether the relevant emission was from a biexciton cascade or a charged exciton recombination.Comment: 5 pages, 3 figure

ANALISIS PUTUSAN HAKIM NOMOR 41/PID.SUS/2018/PN BATU LICIN, TENTANG PERKARA SEDIAAN FARMASI OBAT DAFTAR G JENIS CARNOPEN YANG TIDAK MEMILIKI IJIN DITINJAU DARI ASPEK KEADILAN

The main task of the judge is to accept, examine and try and settle every case submitted to him. It seems very simple for the judge's duties as referred to in Article 2 paragraph 1 of Law Number 48 of 2009, but in reality it is not easy and that simple. The formulation of the problem in this study is 1) What is the Basic Consideration of Judge Judge Number 41 / Pid.Sus / 2018 / PN Batu Licin about the case of circulating pharmaceutical preparations for the list of G types of carnopen that do not have permission? 2) How is the Decision Number 41 / Pid.Sus / 2018 / PN Batu Licin concerning the case of circulating pharmaceutical preparations of the list of drugs G type carnopen that do not have permission in terms of aspects of justice? The approach used in this writing is normative juridical. The data used in this study are primary and secondary data. Analysis of legal materials used in this study is descriptive quality. The results of the analysis show that the basis for the Judgment of Judge Number 41 / Pid.Sus / 2018 / PN Batu Licin about the case of circulating pharmaceutical drug preparations list G types of carnopen which do not have permission, namely subjectively in this case, which is concerning a priori behavioral attitudes, behavioral attitudes emotional, arrogant and moral attitude. Objectively, that is regarding social, cultural and economic backgrounds, professionally. Decision Number 41 / Pid.Sus / 2018 / PN Batu Licin concerning cases circulating pharmaceutical preparations of the list of G types of carnopen which do not have permission in terms of justice, namely 1) declaring the aforementioned Defendant Candra Bin Rahmadi legally and convincingly guilty committing a criminal offense "intentionally circulating Pharmaceutical preparations that do not have marketing authorization" as in the primary indictment 2) Imposing a sentence to the Defendant because of that with imprisonment for 1 (one) year and 2 (two) months and a fine of Rp.2,000,000 00 (two million rupiahs) with the provision that if the fine is not paid is replaced by a confinement for 1 (one) month; and 3) Determine the period of arrest and detention that has been carried out by the Defendant entirely deducted from the sentence imposed