Thermo-optical phase shifter with integrated diodes for multiplexed control

We present a thermo-optic silicon phase shifter with integrated diode, which allows multiplexed access to heaters and reduces the number of pads to drive complex silicon photonics circuits. We also demonstrate that such heaters can be driven using digitally modulated signals, which increases the linearity of the phase shift response of the device

Tolerant, broadband tunable 2 × 2 coupler circuit

We propose a circuit design for a broadband tunable 2 x 2 waveguide coupler, consisting of a two-stage Mach-Zehnder interferometer with electro-optic phase shifters in each stage. We demonstrate that such design can be configured as a tunable coupler with arbitrary coupling ratio and with a uniform response over 50-nm spectral range around 1550 nm. The design is also tolerant to fabrication variations that affect the coupling ratios of the directional couplers

Tolerant, broadband tunable 2x2 coupler circuit

We designed and demonstrated a coupler circuit with tunability for arbitrary coupling ratio and being tolerant to process errors. We also demonstrate that the circuit can be tuned to a uniform coupling spectrum over a 50~nm spectral bandwidth

Column-row addressing of thermo-optic phase shifters for controlling large silicon photonic circuits

We demonstrate a time-multiplexed row-column addressing scheme to drive thermo-optic phase shifters in a silicon photonic circuit. By integrating a diode in series with the heater, we can connect $N \times M$ heaters in an matrix topology to $N$ row and $M$ column lines. The heaters are digitally driven with pulse-width modulation, and time-multiplexed over different channels. This makes it possible to drive the circuit without digital-to-analog converters, and using only $M+N$ wires. We demonstrate this concept with a $1 \times 16$ power splitter tree with 15 thermo-optic phase shifters that are controlled in a $3 \times 5$ matrix, connected through 8 bond pads. This technique is especially useful in silicon photonic circuits with many tuners but limited space for electrical connections

Integrated design for integrated photonics: from the physical to the circuit level and back

Silicon photonics is maturing rapidly on a technology basis, but design challenges are still prevalent. We discuss these challenges and explain how design of photonic integrated circuits needs to be handled on both the circuit as on the physical level. We also present a number of tools based on the IPKISS design framework

ANÁLISE DOS CICLOS DE PRECIPITAÇÃO NA REGIÃO DE BOA VISTA - RR NOS ANOS DE 1910 A 2014

Este estudo buscou relacionar e identificar a influência dos fenômenos ENOS nos índices de precipitação da série histórica (1910 a 2014) da estação pluviométrica de Boa Vista, Capital do Estado de Roraima, Brasil. Os procedimentos metodológicos compreenderam: a) análises estatísticas dos dados diários, mensais e anuais para definição da série pluviométrica identificação de diferentes ciclos pluviométricos; b) identificação e confrontação dos dados pluviométricos com os períodos de vigência dos fenômenos ENOS (El Niño e La Niña) a fim de identificar relações destes com anomalias observadas na série histórica. A análise da série histórica permitiu a identificação de quatro ciclos pluviométricos, representados por dois ciclos secos e outros dois úmidos. Os eventos ENOS (El Niño e La Niña) apresentaram grande compatibilidade com as variações pluviométricas da série. Os resultados apontam para a necessidade do estado e da sociedade civil se organizar aos efeitos dos ciclos de El Niño, em especial a retração do volume superficial de água disponível, estações secas mais fortes e ampliação de eventos de queimadas e, no caso dos ciclos de  La Niña, recorrência de cheias e eventos associados