Search

Nanoscale light sources using metal cavities have been proposed to enable high integration density, efficient operation at low energy per bit and ultra-fast modulation, which would make them attractive for future low-power optical interconnects. For this application, such devices are required to be efficient, waveguide-coupled and integrated on a silicon substrate. We demonstrate a metal-cavity light-emitting diode coupled to a waveguide on silicon. The cavity consists of a metal-coated III–V semiconductor nanopillar which funnels a large fraction of spontaneous emission into the fundamental mode of an InP waveguide bonded to a silicon wafer showing full compatibility with membrane-on-Si photonic integration platforms. The device was characterized through a grating coupler and shows on-chip external quantum efficiency in the 10−4–10−2 range at tens of microamp current injection levels, which greatly exceeds the performance of any waveguide-coupled nanoscale light source integrated on silicon in this current range. Furthermore, direct modulation experiments reveal sub-nanosecond electro-optical response with the potential for multi gigabit per second modulation speeds., Despite much progress, nanoscale light sources suitable for photonic integration are lacking. Here, the authors present a metal-cavity nanopillar LED on a silicon substrate working at telecommunications wavelengths, which demonstrates compatibility with membrane-on-Si photonic integration platforms.

Se realiza cinco temáticas expuestas, la cual se implementará servicios de infraestructura IT con el uso de la plataforma Zentyal Server como suministrador de herramientas para gestionar diversos recursos en seguridad y control. Zentyal server apoya al administrador de infraestructura con una interfaz gráfica desde web que permitirá la configuración adecuada a los escenarios que se requieren, para una buena gestión de recursos de TI. Zentyal server is a Linux-based web platform, designed to be installed on a machine, real or virtual, exclusively. That is why it cannot be installed in other services. Its installation and configuration is manual. Thanks to its graphic web environment, the configuration of services applied to security and control, allows the infrastructure manager to make adjustments to scenarios that are in the organization to offer less performance in their production processes.

El caso “AGOFER: Una decisión para sobrevivir en el mercado del acero en Colombia” trata sobre la decisión que en el año 2010 debían tomar el gerente Juan Guillermo Gómez y la junta de accionistas de Agofer S.A.S, empresa colombiana dedicada a la comercialización de acero y materiales para la construcción en el país, de cómo ser rentable en un mercado altamente competitivo. Teniendo en cuenta la situación del mercado del acero posterior a la crisis económica del 2008, Agofer tenía dos alternativas para hacer frente a la realidad del entorno; por un lado, fortalecer su portafolio con productos complementarios al acero basados en su tradición ferretera y por otro, estaba la posibilidad de hacer parte de un grupo internacional de acero que estaba interesado en adquirir la empresa. El caso busca que los estudiantes apliquen conocimientos y herramientas básicas de la administración y estrategia empresarial, para la toma de decisiones.

The III-V semiconductor InGaAs is a key material for photonics because it provides optical emission and absorption in the 1.55 μm telecommunication wavelength window. However, InGaAs suffers from pronounced nonradiative effects associated with its surface states, which affect the performance of nanophotonic devices for optical interconnects, namely nanolasers and nanodetectors. This work reports the strong suppression of surface recombination of undoped InGaAs/InP nanostructured semiconductor pillars using a combination of ammonium sulfide, (NH4)2S, chemical treatment and silicon oxide, SiOx, coating. An 80-fold enhancement in the photoluminescence (PL) intensity of submicrometer pillars at a wavelength of 1550 nm is observed as compared with the unpassivated nanopillars. The PL decay time of ∼0.3 μm wide square nanopillars is dramatically increased from ∼100 ps to ∼25 ns after sulfur treatment and SiOx coating. The extremely long lifetimes reported here, to our knowledge the highest reported to date for undoped InGaAs nanostructures, are associated with a record-low surface recombination velocity of ∼260 cm/s. We also conclusively show that the SiOx capping layer plays an active role in the passivation. These results are crucial for the future development of high-performance nanoscale optoelectronic devices for applications in energy-efficient data optical links, single-photon sensing, and photovoltaics.

We present an optical amplifier in a membrane based platform for integration with a variety of passive devices. The technology is demonstrated in two DBR lasers, which have 1D and 2D photonic crystal reflectors.

Summary form only given. In this work, we report a remarkable suppression of the surface recombination rates in passivated III-V undoped InGaAs nanopillars on InP (inset of Fig. 1a). The surface passivation comprises ammonium sulfide, (NH4)2S, chemical treatment followed by encapsulation with a 50 nm layer of SiOx by plasma-enhanced chemical vapor deposition performed at 300°C. Before passivation, fabricated nanopillars with -300 nm lateral width, d, show a very poor photoluminescence (PL) emission (blue curve in Fig. 1a). The corresponding carrier dynamics, measured by time-correlated single-photon counting, Fig 1b, reveal an extremely short lifetime of ~130 ps, related to the well-known strong surface recombination velocity at InGaAs surfaces [3]. After the sulfur treatment followed by SiOx, we observe a substantial increase by almost two orders of magnitude of the PL intensity (red curve in Fig. 1a), while the carrier lifetime increases by more than two orders of magnitude to a value ~23 ns, red curve in Fig 1b. The estimated surface recombination velocity, S, decreases from about 2×104 cm/s in the untreated nanopillars down to around 260 cm/s (inset of Fig. 1b). To our knowledge, this is a record low value in undoped InGaAs semiconductors. Most importantly, our passivation studies reveal that the SiOx capping layer not only protects the pillars' sidewalls against oxidation, as reported in [5], but actively takes part in the passivation process, a result never previously reported.

We present an experimental study into the use of simple Fabry Perot lasers for integration in generic platforms. Such integrated FP lasers offer the advantage of freedom of placement anywhere on the chip and, easy integration with monitoring and control functions. They can play a role in short range data communications and they have a potential for 10 Gb/s direct modulation speed. We report first results on experimental realization of such lasers including eye diagrams and BER testing results.

In this work we present the design and technology development for an integrated butt-coupled membrane laser in the IMOS (Indium Phosphide Membrane On Silicon) platform [1]. Laser is expected to have a small footprint (less than 50 μm2), 1 mA threshold current and a direct modulation frequency of 10 GHz.

Grating couplers are widely used to couple light between photonic integrated circuits and optical fibers. Here, we fabricate and characterize a device based on a buried metal grating. In contrast to dielectric gratings, simulations predict strongly reduced parasitic leakage of light to the substrate and are performance independent of the optical buffer thickness, while using standard fabrication processes with high yield. The gratings show a 3 dB bandwidth of 61 nm and chip-to-fiber coupling efficiency of 54%, which makes them attractive building blocks for on-wafer testing and dense optical interconnects.

We developed a novel buried metal grating coupler for membrane platforms. We experimentally demonstrated a chip-to-fiber coupling efficiency of 56%, which makes them an attractive building block for on-wafer testing and dense optical interconnects.

We investigated the passivation of III-V semiconductor nanostructures using wet-chemical ammonium sulfide treatment and SiOx encapsulation. We achieved an ultra-low surface recombination velocity value of ~530 cm/s enabling the future development of high-performance room-temperature nanolasers.

Light sources on the micro and nano-scale are of great interest in recent years. Especially for data communication over centimeters densely integrated lasers are required. Ultra-small devices have been demonstrated[1]; the efficiency of such devices on the other hand is far behind values demonstrated for larger integrated laser concepts [2]. As a consequence the density of laser integration is currently limited by power consumption and cooling properties rather than the actual device footprint. In this work we present a design and first fabrication trials for a micron-scale laser promising record efficiencies exceeding 20%. A schematic representation of the laser is shown in figure 1 a).

We propose a novel metal grating coupler compatible with membrane-based integrated photonics with coupling efficiency as high as 89%. The device performance is independent from the underlying layer stack, enabling its use in diverse applications.

This paper reports the progress on the fabrication process of highly efficient metal grating couplers for membrane-based integrated circuits, using double side processing technology on bonded samples. This type of gratings comprises a buried SiO2/Ag grating of 125nm thickness with a silver layer as metal mirror, and has several advantages over dielectric gratings as metallic gratings are independent from the buffer thickness. We predict a theoretical chip-to-fiber coupling efficiency of 74% and 89% for uniform and apodized gratings respectively, at a wavelength of 1550 nm. Furthermore, the fabrication process can be used for both, SOI and III-V based platforms.

Densely integrated light sources are essential for centimeter scale data communication. In this paper we examine the factors and challenges influencing the efficiency of such devices. We then focus on studying the performance of reflector and out-coupling concepts using finite different time domain simulations. Keywords: integrated photonics, nanolasers, reflectors, waveguide-coupling.

Optical data links are employed at ever shorter distances, most recently with a few meters length in between cabinets in warehouse sized computer systems. A continuation of this trend to optical chip-to-chip and on-chip communication will require highly efficient and densely integrated optical devices. We will discuss general requirements to achieve such targets in nano- and micro- scale lasers integrated with a photonic membrane platform, where we focus on the optical cavity design and the electrical properties. Additionally, we will compare the advantages of laser concepts based on metallic-dielectric confinement, photonic crystal cavities and distributed feedback using sidewall gratings.

Fractional photothermolysis uses lasers to generate a pattern of microscopic columnar thermal lesions within the skin stimulating collagen remodeling. In this paper we investigate the use of Bessel beams as an alternative to conventional Gaussian beams in creating laser photothermal lesions of different aspect ratios in skin. We show for the first time the improved photothermal lesion depth-to-diameter aspect ratio using Bessel beams in ex vivo human skin as well as in numerical simulations using electric field Monte Carlo photon transport, finite difference methods and Arrhenius model. Bessel beams allow the creation of deep and narrow thermal lesions necessary for improved efficacy in fractional photothermolysis.