Made available in DSpace on 2014-10-09T12:51:06Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:22Z (GMT). No. of bitstreams: 1 11245.pdf: 3839008 bytes, checksum: 2374cc538329b29558236be14950ccdf (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

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Made available in DSpace on 2014-10-09T12:51:25Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:53Z (GMT). No. of bitstreams: 1 11306.pdf: 5168610 bytes, checksum: bc65302ba021a7b116fa1e5360103483 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo

Orientador: Flavio Caldas da Cruz / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-06T01:07:38Z (GMT). No. of bitstreams: 1 Figueira_DaviddaSilvaLeocadio_M.pdf: 3869897 bytes, checksum: 4f234a84a87a86465d0b4e90fa141658 (MD5) Previous issue date: 2004 / Resumo: Esta tese apresenta o desenvolvimento de fontes de radiação coerente na região do azul baseadas em lasers semicondutores para excitar a transição de resfriamento e aprisionamento 1 S0-1P1 do Cálcio, em 423nm. Foi construído um laser de diodo em cavidade estendida emitindo em g =846 nm que foi empregado em uma configuração de Cavidade Estendida de Littman, estabilizada em freqüência pela técnica de Side-of-Fringe. Parte da potência deste laser foi amplificada por um amplificador óptico semicondutor. Potências superiores a 700mW em g =846nm foram obtidas. Parte desta potência do amplificador óptico (450mw) foi duplicada em frequência para g =423nm em um cristal de niobato de potássio(KNbO3), utilizado dentro de uma cavidade óptica ressonante com a freqüência do laser. A estabilização da cavidade óptica duplicadora de freqüência foi feita pela técnica de Hansch-Coulliaud . O sistema desenvolvido alcançou potências de 60mW de radiação coerente azul. Esta fonte laser portátil deverá ser utilizada para espectroscopia, resfriamento e aprisionamento de Cálcio / Abstract: This thesis presents the development of sources of coherent radiation in the blue region of the spectrum, based on semiconductors lasers, to excite the cooling and trapping 1S0-1P1 transition of neutral calcium atoms at 423nm. A diode laser emitting at g =846 nm was employed in an extended cavity Littman configuration, and stabilized in frequency by the Side-of-Fringe technique. Part of the laser power was amplified by an optical semiconductor amplifier. Output powers above 700mW at g =846nm were obtained. Part of this amplified power (450mW) was frequency doubled to g =423nm in a potassium niobate (KNbO3) crystal, placed inside a resonant optical cavity. The lock of the doubling optical cavity was made by the Hansch-Coulliaud technique. The developed system reached powers near 60mW of blue coherent radiation at 423nm. This portable laser source will be used for spectroscopy, cooling and trapping of calcium / Mestrado / Física / Mestre em Física

Made available in DSpace on 2014-10-09T12:51:06Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:22Z (GMT). No. of bitstreams: 1 11245.pdf: 3839008 bytes, checksum: 2374cc538329b29558236be14950ccdf (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:45:41Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:18Z (GMT). No. of bitstreams: 1 07609.pdf: 2103835 bytes, checksum: daf8a4e12257ed226478079afb3ed0d5 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo

Made available in DSpace on 2014-10-09T12:51:25Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:53Z (GMT). No. of bitstreams: 1 11306.pdf: 5168610 bytes, checksum: bc65302ba021a7b116fa1e5360103483 (MD5) / Dissertacao (Mestrado Profissionalizante em Lasers em Odontologia) / IPEN/D-MPLO / Instituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP; Faculdade de Odontologia, Universidade de Sao Paulo

Cette thèse s’est concentrée sur l’étude des lasers à blocage de modes destinés à la fenêtre de télécommunication de 1,55 µm et à base de bâtonnets quantiques dont la croissance a été réalisée sur des substrats d’InP. Un des principaux objectifs de ce travail de thèse a consisté à apporter de nouveaux éléments permettant de mieux appréhender les aspects physiques sous-tendant le mécanisme du ML dans ces dispositifs. En effet, une meilleure compréhension du comportement intrinsèque de ces dispositifs et la façon dont ils sont affectés par des facteurs externes, qui pourraient être présents dans les conditions réelles d’utilisation, est cruciale pour leur intégration dans des technologies futures. Un deuxième objectif majeur de ce travail a consisté à démontrer le potentiel d’exploitation de ces dispositifs dans différents scenarii d’applications / This PhD thesis focuses on the study of mode locked laser diodes based on novel optimized InAs Quantum Dash structures grown on InP substrates. It covers several important modelling aspects, the clean room processing of single and two section shallow ridge waveguide lasers, characterization of the fabricated devices and the evaluation of their performance in different application scenarios. Systematic characterization experiments and subsequent analyses have allowed to gain a much deeper comprehension of the physical mechanisms related to the mode locking regime in these devices, thus far not completely understood. This has allowed to better control most of the main physical phenomena limiting device performance, resulting in first demonstrations of record peak power, sub-picosecond pulse, low radio frequency linewidth and high repetition frequency mode locked lasers grown on InP substrates, opening the way to a vast number of potential applications in the 1.55 µm telecommunication window

A novel dispersion-managed breathing-mode semiconductor mode-locked ring laser is developed. The "breathing-mode" designation derives from the fact that intracavity pulses are alternately stretched and compressed as they circulate around the ring resonator. The pulses are stretched before entering the semiconductor gain medium to minimize the detrimental strong integrating self-phase modulation and to enable efficient pulse amplification. Subsequently compressed pulses facilitate bleaching the semiconductor saturable absorber. The intracavity pulse compression ratio is higher than 50. Down chirping when compared to up chirping allows broader mode-locked spectra and shorter pulse generation owing to temporal and spectral semiconductor gain dynamics. Pulses as short as 185 fs, with a peak power of ~230 w, and a focused intensity of ~4.6 gw/cm2 are generated by linear down chirp compensation and characterized by shg-frog method. To our knowledge, this is the highest peak power and the shortest pulse generation from an electrically pumped all-semiconductor system. The very good agreement between the simulated and the measured results verifies our understanding and ability to control the physical mechanisms involved in the pulse shaping within the ring cavity. Application trends such as continuum generation via a photonic crystal fiber, two-photon fluorescence imaging, and ultrafast pulse source for pump-probe experiments are demonstrated.

Harmonically mode-locked semiconductor lasers with external ring cavities offer high repetition rate pulse trains while maintaining low optical linewidth via long cavity storage times. Single frequency injection locking generates widely-spaced and tunable frequency combs from these harmonically mode-locked lasers, while stabilizing the optical frequencies. The output is stabilized long-term with the help of a feedback loop utilizing either a novel technique based on Pound-Drever-Hall stabilization or by polarization spectroscopy. Error signals of both techniques are simulated and compared to experimentally obtained signals. Frequency combs spaced by 2.5 GHz and ~10 GHz are generated, with demonstrated optical sidemode suppression of unwanted modes of 36 dB, as well as RF supermode noise suppression of 14 dB for longer than 1 hour. In addition to the injection locking of actively harmonically mode-locked lasers, the injection locking technique for regeneratively mode-locked lasers, or Coupled OptoElectronic Oscillators (COEOs), is also demonstrated and characterized extensively.