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

• Main Authors: Chun-Yi Chen, 陳俊亦
• Other Authors: Chao-Yi Tai
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/82814998229745203101

碩士 === 國立中央大學 === 光電科學研究所 === 94 === 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.