拉曼放大器在光通訊中是重要的元件，在光纖通訊中，光訊號的能量會在傳輸過程中隨著傳遞距離而減少，所以必須藉由放大器將光訊號放大，本論文是以矽波導來觀察拉曼放大的現象，矽波導的優點拉曼增益係數遠大於玻璃光纖，而製作出的元件可以縮到一個晶片大小，在論文中，希望藉由矽的高拉曼係數，同時利用矽波導環共振腔的共振放大效應，製作出拉曼放大的元件。我們在量測結果中，有觀察到拉曼放大的訊號，也發現有自由載子吸收的情形。元件波導的結構是多模態波導而非單模波導，採用多模態波導的原因是想增加光纖的耦合效率，同時利用微機電製程來達成波導與共振腔之間的光耦合，元件製程是以直接深蝕刻的方式蝕刻出高5um的波導來製作，由於波導的損耗過大，導致拉曼放大的現象不明顯，此外，由於原因波導非單模態而是多模態波導，光在圓共振腔會產生耦合損能，要改善元件的效率，我們可以使用新型線波導的結構，以同樣的方式來製作拉曼放大器，由於此波導是單模態波導且損耗較低，所以此波導來製作拉曼放大元件會優於多模態波導，有機會達成拉曼雷射的元件。

Raman amplifiers are important for optical communication because the power of signal gradually reduces along propagation. We must use amplifiers to recover signal power strong enough for defection. A Raman amplifier is one kind of amplifiers. The Raman coefficient in silicon is much higher than in fiber(10000 times) ,and it is a reason that we are interested using silicon waveguides to make a amplifier. The size of silicon Raman amplifiers is very small and can be integrated with other devices to accomplish many optical functions on a chip. In this thesis, we take advantage of high Raman coefficient in silicon and utilize resonant enhancement of microring resonators to make Raman amplifiers on silicon-on-insulator. In order to have better waveguide-fiber coupling, we use multimode waveguides and apply micro-electro-mechonical-system (MEMS) technology to allow waveguide and microring well coupled. In measurement, we observe spontaneous and stimulation Raman scattering by controlling the input power. When input power is higher, we also discover the free carrier effect affecting the signal power and refractive index of waveguide. However the loss of device is too high and we can’t adjust the power coupling ratio ,causing that Raman effect is not obvious. To improve the efficiency of device, we could use a novel low-loss silicon photonic wire to make our device in the future. The novel low-loss silicon photonic wire has advantages in low loss and single guide mode. So we expect that it can be better than multimode waveguide and maybe generates Raman laser.

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