錐狀平面波導光柵結構與微米小球共振腔之光耦合效率研究

High-Q Whispering Gallery Mode Coupler Utilizing a Tapered Wavwguide with a Side-tap grating Structure

陳俊亦(Chun-Yi Chen)

指導教授 ： 戴朝義

國立中央大學/理學院/光電科學研究所/碩士(2006年)

摘要

本論文提出可晶片化（on-chip）之球型共振腔耦合器，可應用在光的訊號轉換及光相位延遲等研究。我們利用標準的光微影技術，在矽基板上製作此微光學元件，使其達到高穩定性與可批次製造等優點。
在設計上，波導與微米球型共振腔的耦合效率可達26％，且此元件具有波長選擇性，此元件設計波長為1550nm，耦合效率隨輸入波長偏移設計波長，當波長偏移量達100nm 時，耦合效率降至最大值之60﹪。最後，實驗上也印證了與模擬設計相同的結果。

關鍵字

耦合 ； 平面波導 ； 球型共振腔 ； 光柵 ； 錐狀波導

並列摘要

Most of the demonstrated devices utilize a tapered fiber to excite the Whispering gallery modes (WGMs), however this coupling architecture not only lacks of rigid stability but inhibits dense integration. In this thesis, we report an alternative scheme based on a tapered waveguide in company with a side-tap grating structure. This approach provides better mechanical stability and is compatible with existing Si fabrication process.
The calculated coupling efficiency is a function of the input wavelength at various grating periods. And the highest coupling efficiency reaches ~26% with the grating period Λ=5.486 μm at λ~1530 nm, which is in close agreement with the phase matching condition predicted by the grating theory. It is worth mentioning that the smallest feature size in this design is well beyond 1μm, indicating that less stringent fabrication tolerance over the tapered fiber and the standard photolithography process can accomplish the task.

並列關鍵字

grating ； microsphere ； planar waveguide ； taper ； whispering gallery mode

參考文獻

[4]Ming Cai ,Kerry Vahala,” Highly efficient optical power transfer to whispering-gallery modes by use of a symmetrical dual-coupling configuration”,OPTICS LETTERS ,25,4（2000）.

[5]B. E.Little, J.-P. Laine, D. R. Lim, and H. A. Haus,” Pedestal antiresonant reflecting waveguides for robust coupling to microsphere resonators and for microphotonic circuits”, OPTICS LETTERS ,25,1（2000）.

[6]A. Mazzei, S. Gotzinger, L.de S. Menezes, V. Sandoghdar, O. Benson, “Optimization of prism coupling to high-Q modes in a microsphere resonator using a near-field probe”,Optics Communications 250 (2005) 428–433.

[7]N. Dubreuil, J. C. Knight, D. K. Leventhal, V. Sandoghdar, J. Hare, and V. Lefevre,“Eroded monomode optical fiber for whispering-gallery mode excitation in fused-silica microspheres”, OPTICS LETTERS, 20, 8（1995）.

[8]Vladimir S. Ilchenko, X. Steve Yao, and Lute Maleki“Pigtailing the high-Q microsphere cavity: a simple fiber coupler for optical whispering-gallery modes”, OPTICS LETTERS, 24, 11（1999）.