In this thesis, we have compared between dual-core fiber coupler with photonic crystal fiber coupler. From Surface Integral Equation Method derived from Maxwell¡¦s equations, we can simulate tapered fiber coupler, dual-core fiber coupler and photonic crystal fiber coupler. By analyzing the propagating characteristics and performance of these couplers, we hope to discuss between their advantages and dis-advantages. We have found that at the same parameters, conventional fiber coupler¡¦s coupling length is roughly half compared to photonic crystal coupler. In terms of bandwidth, photonic crystal coupler aided by air-hole tuning can achieve multiples times larger than conventional fiber coupler. So, we believe that in communication networks with a lust of bandwidth, photonic crystal coupler can definitely live up its expectations.

A single-mode fused biconical 2¡Ñ2 coupler for polarization beamsplitting is fabricated in this thesis. We use simple fused and tapered method to fabricate the polarization beamsplitter(PBS) stably, and then we can get polarization maintaining in the output fibers. Without changing the manufacturing process, we design the device with special combination of fabrication parameters. We have achieved an extinction ratio of 25.78dB at the throughput port and 27.16dB at the coupled port. A usable spectral window as broad as 37nm and 27nm with an extinction ratio larger than 15dB for both ports is obtained. The excess loss is about 0.3dB. Based on a full-wave numerical approach, the performance of the PBS can be well modeled. We get good agreement between the measured and simulated results.

The aim of this research is to evaluate sound insulation behavior of double windows, when a second window is placed upon a previous one, keeping an air layer between them. This was done through standard tests carried out at the reverberation chambers of the Thermo Acoustics Laboratory, of Universidade Federal de Santa Maria in accordance with ISO 140-III, ISO 717-I international norms and the Brazilian Norm Project 02:135.01-001. First, low air hermetic windows were duplicated, each one having Rw = 18 dB. Second, good air hermetic windows were duplicated. The objective, through this technique, was to find out sound insulation improvement of double windows under the two mentioned circumstances. Observing the test results, it was verified that low air hermetic double window obtained Rw = 26 dB, with an increase of 8 dB in relation to just one window of the same typology. Insulation gain, in this case, occurred mainly in medium and high frequencies. In relation to good air hermetic double window, a Rw final of 37 dB was obtained, considering that the increase in sound insulation depends on the initial performance of the fist installed window. The gain in insulation in the second instance was between 4 to 8 dB, mainly in relation to low and medium frequencies. Therefore, it was possible to quantify which sound insulation improvement could be done on façades employing the technique of double windows in order to contribute to the betterment and quality of buildings in Brazil / A proposta deste trabalho é avaliar o comportamento da isolação sonora de janelas duplas, em que uma segunda janela é sobreposta a outra já existente, havendo entre ambas uma camada de ar. Tal determinação é feita mediante ensaios normalizados nas câmaras reverberantes do Laboratório de Termo Acústica da Universidade Federal de Santa Maria, de acordo com as normas internacionais ISO 140-III, ISO 717-I e Projeto de Norma Brasileira 02:135.01-001. Inicialmente foram duplicadas janelas com baixa estanqüeidade ao ar, tendo Rw = 18 dB cada uma, e a seguir, janelas com boa estanqüeidade. Buscou-se, através dessa técnica, conhecer o desempenho sonoro da duplicação de janelas nestas duas situações consideradas. A partir dos resultados dos ensaios, verificou-se que a duplicação de janelas com baixa estanqüeidade ao ar atingiu um Rw = 26 dB, com acréscimo de 8 dB em relação à uma única janela de mesma tipologia. O ganho de isolamento, nesse caso, ocorreu principalmente nas médias e altas freqüências. Em relação à duplicação de janelas com boa estanqüeidade, atingiu-se um Rw final de 37 dB, sendo o acréscimo no isolamento acústico dependente do desempenho inicial da primeira janela. O ganho em isolamento nesta segunda situação foi de 4 a 8 dB, com incidência sobretudo nas baixas e médias freqüências. Dessa maneira, pôde-se quantificar qual a melhoria do isolamento sonoro em fachadas, a partir da duplicação de janelas, de forma a contribuir para o aperfeiçoamento e qualidade das construções em nosso país