2,284 research outputs found
Ultrashort-pulse generation from quantum-dot semiconductor diode lasers
No full textIn this thesis, novel regimes of mode locking in quantum dot semiconductor laser diodes have been investigated by exploiting the unique features offered by quantum dots. Using an unconventional approach, the role of excited state transitions in the quantum dots was exploited as an additional degree of freedom for the mode locking of experimental quantum dot lasers.
For the first time, passive mode locking via ground (1260nm) or excited state (1190nm) was demonstrated in a quantum dot laser. Picosecond pulses were generated at a repetition rate of 21GHz and 20.5GHz, for the ground and excited states respectively, with average powers in excess of 25mW. Switching between these two states in the mode-locking regime was achieved by changing the electrical biasing conditions, thus providing full control of the operating spectral band.
A novel regime for mode locking in a quantum-dot laser was also investigated, where the simultaneous presence of cw emission in the excited-state band at high injection current levels, dramatically reduced the duration of the pulses generated via the ground state, whilst simultaneously boosting its peak power. This represents a radically different trend from the one typically observed in mode-locked lasers. From this investigation, it was concluded that the role of the excited state can not be neglected in the generation of ultrashort pulses from quantum-dot lasers.
Stable passive mode locking of a quantum-dot laser over an extended temperature range (from 20ºC to 80ºC) was also demonstrated at relatively high output average powers. It was observed that the pulse duration and the spectral width decreased significantly as the temperature was increased up to 70ºC. The process of carrier escape in the absorber was identified as the main contributing factor that led to a decrease in the absorber recovery time as a function of increasing temperature which facilitated a decrease in the pulse durations. These results are shown to open the way for the ultimate deployment of ultra stable and uncooled mode-locked semiconductor diode lasers
Imagens de Otto Maria Carpeaux: esboço de biografia
Full text linkTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas, Programa de Pós-Graduação em História, Florianópolis, 2015.Este esboço de biografia procura citar algumas imagens de Otto Maria Carpeaux: construções biográficas de naturezas múltiplas, elaboradas em contextos, por atores e sob condições igualmente díspares. Está constituído a partir de uma visão crítica da História, o que permite que ?outras imagens?, fragmentárias e não monumentais, também tenham espaço. Em diálogo com o princípio da montagem, este esboço apresenta-se em duas partes. Na primeira, Imagens possíveis, estão citadas as imagens elaboradas em vida e post mortem acerca do austríaco-brasileiro que nasceu em Viena em 1900, se exilou no Brasil em 1939 e morreu no Rio de Janeiro, em 1978. Na segunda, Montagens possíveis, apresentam-se duas possibilidades de exercício biográfico: pela leitura alegórica do documentário O velho e o Novo (Otto Maria Carpeaux), entendido como instrumento de intervenção no contexto ditatorial brasileiro e de uma reelaboração biográfica concernentes às suas experiências europeias; e pelo Caderno de imagens críticas, registro dos encontros em Carpeaux pelo meio de imagens críticas produzidas a partir da cesura do presente.Abstract : This biographical sketch attempts to quote some images of Otto Maria Carpeaux: various types of biographical constructions, carried out in different contexts by disparate authors under conditions just as distinct. It stems from a critical view of history, allowing for ?other images? fragmented and non-monumental ? to share the space.In dialogue with the montage principle, this sketch has two parts. The first, Possible Images, quotes the images produced during and after the life of the Austrian-Brazilian, who was born in Vienna in 1900, went to Brazil in exile in 1939 and died in Rio de Janeiro in 1978. The second part, Possible Montages, presents two possibilities of a biographical exercise: through the allegorical reading of documentary O Velho e o Novo (Otto Maria Carpeaux), understood as an instrument of intervention in the Brazilian dictatorship context and as a biographical retelling of the author?s European experiences; and through my Scrapbook of Critical Images, a record of the encounters in Carpeaux through critical images produced from the caesura of the present
Time-Domain Travelling-Wave Analysis of Semiconductor Optical Amplifiers based on Chirped Quantum Dot Materials
Full text linkWe numerically study a tapered chirped Quantum Dot Semiconductor Optical Amplifier operating in the 1100nm-1350nm wavelength range, showing good agreement with experiments in terms of pulse amplification in both the single- and double-pass setups
A luta contra o preconceito em Graciliano Ramos e Ana Maria Machado
No full textUnlike most of the literary production of the period, Gra- ciliano Ramos, in the short story «A Terra dos Meninos Pelados», anticipates, in an innovative way, techniques and narrative processes, also showing himself as a skillful precursor in relation to the theme of prejudice, which would gain an even more fundamental role in Brazilian children’s literary production. Comparing the motifs and narrative techniques that connote the tale of the aforementioned author from Alagoas with those of the book Raul da Ferrugem Azul, by Ana Maria Machado, we will evaluate the ways in which these two authors bring a novelty to Brazilian literature and the younger audience
Viajantes ex-cêntricas nas histórias de Ana Miranda
Full text linkTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Literatura.No conjunto das narrativas ficcionais da escritora brasileira Ana Miranda, a temática da viagem # considerada uma das mais férteis da literatura ocidental de todos os tempos # ocupa um espaço de centralidade, podendo até mesmo ser vista como o mais importante eixo de estruturação de suas obras. O estudo realizado pela presente tese tem por objetivo analisar o tratamento dado ao tema da viagem nos romances Desmundo, O retrato do rei, Dias & Dias e Amrik, evidenciando que por intermédio das narradora-viajantes # Oribela, Mariana, Feliciana e Amina # a autora promove um diálogo entre diferentes culturas, gêneros, etnias e gerações, ao mesmo tempo em que estabelece um profícuo diálogo com o passado em sua invariante problematização concernente aos limites e cruzamentos entre o discurso ficcional e os discursos narrativos extraliterários que o cercam, sobretudo o histórico e o biográfico. In the whole of Brazilian writer Ana Miranda#s fictional narrative, the travel thematic # considered one of the most fertile themes of the western literature of all times # occupies a central space, and can even been seen as the most important structuring axis of Miranda#s works. The aim of the present thesis is to analyze the treatment given to the travel subject in the novels Desmundo, O retrato do rei, Dias & Dias and Amrik, emphasizing that, through the traveling narrators, Oribela, Mariana, Feliciana and Amina, the author promotes a connection between different cultures, genders, ethnics and generations, at the same time that establishes a profitable dialogue with the past in her invariant problematization concerning the limits and crossings between the fictional and the extra-literary narrative discourses that surrounds it, mainly the historical and the biographic ones
Um país todo seu: o protagonismo feminino em Um Mapa todo seu, de Ana Maria Machado
Full text link[ES] Entre el 26 de abril y el 7 de mayo de 2021 se celebró en el Centro de Estudios Brasileños de la Universidad de Salamanca el II Congreso Internacional de Literatura Brasileña “Ana Maria Machado y el compromiso literario”. Todavía en una de las etapas más difíciles de la pandemia por COVID-19, el encuentro fue enteramente online. Este libro recoge algunas de las más significativas aportaciones del Congreso en el que se trataron cuestiones de Literatura brasileña en general y sobre la escritora carioca en particular. Destaca entre ellas la aportación de la propia Ana Maria, un texto en el que rememora su primer encuentro no trivial con Clarice Lispector, una escritora célebre que misteriosamente requirió la presencia en su casa de Ana Maria Machado, por aquel entonces una editora de radio, desconocida para el público, que se había doctorado en París con una tesis dirigida por Roland Barthes. Clarice quería que la ayudara a ordenar los materiales de lo que finalmente sería su obra A hora da estrela, publicada en 1977 poco tiempo antes de su muerte, a lo que Ana Maria se negó con el ánimo de ser honrada y de que Clarice fortaleciera su autoestima.
Acompañando a este primer trabajo aparecen los de importantes brasileñistas a ambos lados del Atlántico, muchos de los cuales se decantan por el análisis del componente femenino en la obra de la autora, incluso encontramos trabajos sobre el compromiso de Ana María con las mujeres y desde perspectivas abiertamente feministas. Además, hay en esta obra análisis certeros sobre algunas de las obras más significativas de Machado, tanto en su faceta de escritora para adultos como en la de literatura infantil y juvenil. En este libro descubrimos análisis críticos que se basan en la Teoría literaria, trabajos generales de carácter histórico y análisis comparatistas que ayudarán a entender mejor la inestimable producción de esta autora.Así, el lector podrá encontrar reflexiones sobre Tropical sol da liberdade, Palavra de honra, A audácia dessa mulher o Um mapa todo seu, pero también sobre Raul da ferrugem azul, Procura-se lobo, O veado e a onça o Menina bonita do laço de fita, entre otros. En este libro descubrimos análisis críticos que se basan en la Teoría literaria, trabajos generales de carácter histórico y análisis comparatistas que ayudarán a entender mejor la inestimable producción de esta autora.[EN] Between April 26 and May 7, 2021, the II International Congress of Brazilian Literature 'Ana Maria Machado and literary commitment' was held at the Centro de Estudios Brasileños of the University of Salamanca. The meeting was entirely online. This book collects some of the most significant contributions of the Congress in which issues of Brazilian Literature in general and about Machado, in particular, were discussed. Among them, the contribution of Ana Maria herself stands out, a text in which she recalls her first non-trivial encounter with Clarice Lispector. Accompanying this first work are those of important Brazilian researchers on both sides of the Atlantic. Many of them deal with women’s issues. In addition, in this work there are accurate analyzes of some of Machado's most significant works, both in her role as a writer for adults and in children's and youth literature. Thus, the reader will be able to find reflections on Tropical sol da liberdade, Palavra de honra, A audácia dessa mulher or Um mapa todo seu, but also on Raul da ferrugem azul, Procura-se lobo, O veado e a onça or Menina bonita do laço de fita, among others. In this book we discover critical analyzes based on literary theory, general works of a historical nature, and comparative works that will help to understand the invaluable production of this author
Ana Maria Machado y el compromiso literario
Full text link[ES] Entre el 26 de abril y el 7 de mayo de 2021 se celebró en el Centro de Estudios Brasileños de la Universidad de Salamanca el II Congreso Internacional de Literatura Brasileña “Ana Maria Machado y el compromiso literario”. Todavía en una de las etapas más difíciles de la pandemia por COVID-19, el encuentro fue enteramente online. Este libro recoge algunas de las más significativas aportaciones del Congreso en el que se trataron cuestiones de Literatura brasileña en general y sobre la escritora carioca en particular. Destaca entre ellas la aportación de la propia Ana Maria, un texto en el que rememora su primer encuentro no trivial con Clarice Lispector, una escritora célebre que misteriosamente requirió la presencia en su casa de Ana Maria Machado, por aquel entonces una editora de radio, desconocida para el público, que se había doctorado en París con una tesis dirigida por Roland Barthes. Clarice quería que la ayudara a ordenar los materiales de lo que finalmente sería su obra A hora da estrela, publicada en 1977 poco tiempo antes de su muerte, a lo que Ana Maria se negó con el ánimo de ser honrada y de que Clarice fortaleciera su autoestima.
Acompañando a este primer trabajo aparecen los de importantes brasileñistas a ambos lados del Atlántico, muchos de los cuales se decantan por el análisis del componente femenino en la obra de la autora, incluso encontramos trabajos sobre el compromiso de Ana María con las mujeres y desde perspectivas abiertamente feministas. Además, hay en esta obra análisis certeros sobre algunas de las obras más significativas de Machado, tanto en su faceta de escritora para adultos como en la de literatura infantil y juvenil. En este libro descubrimos análisis críticos que se basan en la Teoría literaria, trabajos generales de carácter histórico y análisis comparatistas que ayudarán a entender mejor la inestimable producción de esta autora.Así, el lector podrá encontrar reflexiones sobre Tropical sol da liberdade, Palavra de honra, A audácia dessa mulher o Um mapa todo seu, pero también sobre Raul da ferrugem azul, Procura-se lobo, O veado e a onça o Menina bonita do laço de fita, entre otros. En este libro descubrimos análisis críticos que se basan en la Teoría literaria, trabajos generales de carácter histórico y análisis comparatistas que ayudarán a entender mejor la inestimable producción de esta autora.[EN] Between April 26 and May 7, 2021, the II International Congress of Brazilian Literature 'Ana Maria Machado and literary commitment' was held at the Centro de Estudios Brasileños of the University of Salamanca. The meeting was entirely online. This book collects some of the most significant contributions of the Congress in which issues of Brazilian Literature in general and about Machado, in particular, were discussed. Among them, the contribution of Ana Maria herself stands out, a text in which she recalls her first non-trivial encounter with Clarice Lispector. Accompanying this first work are those of important Brazilian researchers on both sides of the Atlantic. Many of them deal with women’s issues. In addition, in this work there are accurate analyzes of some of Machado's most significant works, both in her role as a writer for adults and in children's and youth literature. Thus, the reader will be able to find reflections on Tropical sol da liberdade, Palavra de honra, A audácia dessa mulher or Um mapa todo seu, but also on Raul da ferrugem azul, Procura-se lobo, O veado e a onça or Menina bonita do laço de fita, among others. In this book we discover critical analyzes based on literary theory, general works of a historical nature, and comparative works that will help to understand the invaluable production of this author
Ana Maria Machado, palabra de mujer
Full text link[ES] Entre el 26 de abril y el 7 de mayo de 2021 se celebró en el Centro de Estudios Brasileños de la Universidad de Salamanca el II Congreso Internacional de Literatura Brasileña “Ana Maria Machado y el compromiso literario”. Todavía en una de las etapas más difíciles de la pandemia por COVID-19, el encuentro fue enteramente online. Este libro recoge algunas de las más significativas aportaciones del Congreso en el que se trataron cuestiones de Literatura brasileña en general y sobre la escritora carioca en particular. Destaca entre ellas la aportación de la propia Ana Maria, un texto en el que rememora su primer encuentro no trivial con Clarice Lispector, una escritora célebre que misteriosamente requirió la presencia en su casa de Ana Maria Machado, por aquel entonces una editora de radio, desconocida para el público, que se había doctorado en París con una tesis dirigida por Roland Barthes. Clarice quería que la ayudara a ordenar los materiales de lo que finalmente sería su obra A hora da estrela, publicada en 1977 poco tiempo antes de su muerte, a lo que Ana Maria se negó con el ánimo de ser honrada y de que Clarice fortaleciera su autoestima.
Acompañando a este primer trabajo aparecen los de importantes brasileñistas a ambos lados del Atlántico, muchos de los cuales se decantan por el análisis del componente femenino en la obra de la autora, incluso encontramos trabajos sobre el compromiso de Ana María con las mujeres y desde perspectivas abiertamente feministas. Además, hay en esta obra análisis certeros sobre algunas de las obras más significativas de Machado, tanto en su faceta de escritora para adultos como en la de literatura infantil y juvenil. En este libro descubrimos análisis críticos que se basan en la Teoría literaria, trabajos generales de carácter histórico y análisis comparatistas que ayudarán a entender mejor la inestimable producción de esta autora.Así, el lector podrá encontrar reflexiones sobre Tropical sol da liberdade, Palavra de honra, A audácia dessa mulher o Um mapa todo seu, pero también sobre Raul da ferrugem azul, Procura-se lobo, O veado e a onça o Menina bonita do laço de fita, entre otros. En este libro descubrimos análisis críticos que se basan en la Teoría literaria, trabajos generales de carácter histórico y análisis comparatistas que ayudarán a entender mejor la inestimable producción de esta autora.[EN] Between April 26 and May 7, 2021, the II International Congress of Brazilian Literature 'Ana Maria Machado and literary commitment' was held at the Centro de Estudios Brasileños of the University of Salamanca. The meeting was entirely online. This book collects some of the most significant contributions of the Congress in which issues of Brazilian Literature in general and about Machado, in particular, were discussed. Among them, the contribution of Ana Maria herself stands out, a text in which she recalls her first non-trivial encounter with Clarice Lispector. Accompanying this first work are those of important Brazilian researchers on both sides of the Atlantic. Many of them deal with women’s issues. In addition, in this work there are accurate analyzes of some of Machado's most significant works, both in her role as a writer for adults and in children's and youth literature. Thus, the reader will be able to find reflections on Tropical sol da liberdade, Palavra de honra, A audácia dessa mulher or Um mapa todo seu, but also on Raul da ferrugem azul, Procura-se lobo, O veado e a onça or Menina bonita do laço de fita, among others. In this book we discover critical analyzes based on literary theory, general works of a historical nature, and comparative works that will help to understand the invaluable production of this author
Operating regimes of injection-locked quantum-dot lasers and applications in high-speed optical sampling
No full textAbstract currently unavailable. Restricted access until 31.08.2024. Please refer to PDF
High-power quantum-dot superluminescent tapered diode under CW operation
Full text linkA high-power quantum-dot superluminescent diode is demonstrated under continuous-wave operation, with an output power of 137.5 mW and a corresponding spectral bandwidth of 21 nm. This represents not only the highest output power, but also a record-high power spectral density of 6.5 mW/nm for a CW-operated superluminescent diode in the 1.1 - 1.3 μm spectral region, marking more than a 6-fold increase with respect to the state of the art. The two-section contact layout of the reported device introduces additional degrees of freedom, which enable a wide tunability of the bandwidth and power depending on the desired application. A maximum bandwidth of 79 nm was recorded, with an output power of 1.4 mW. The high-power continuous-wave operation of this device would be particularly relevant for continuous, high-speed, high-sensitivity spectroscopy, imaging and sensing applications, as well as in optical communications.</p
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