Grating-assisted-cylindrical-resonant-cavities interlayer coupler.
Grating-assisted-cylindrical-resonant-cavities interlayer coupler.
复制标题
光栅辅助圆柱形谐振腔层间耦合器。
作者：
Congshan Wan;T. Gaylord;M. Bakir
为了实现高效、宽带的层间耦合，设计并仿真了一种由Si/SiO2制成的光栅辅助圆柱共振腔（GARC）层间耦合器。该耦合器由三个圆柱谐振腔组成：两个水平方向的波导腔和一个垂直方向的圆柱通孔腔。圆形贝塞尔函数定义光栅和分布布拉格反射器增强了两个圆柱形波导腔的谐振强度。在1.55 μm波长下，该Si/SiO2 GARC耦合器的层间耦合效率为ηc=68%(-1.7 dB)，具有反射器、复层、啁啾周期、双光栅等特性，普遍高于传统的矩形绝缘体上硅光栅。与以前的耦合器相比，GARC耦合器预计具有良好的特性，包括更宽的工作带宽（δλ,1 dB=270 nm），更大的面内偏差容错性（1 dB额外损耗±2 μm），更容易光栅图图化（更宽的光栅脊），更小的占地面积（直径20 μm），以及更灵活的层间距离选择（2-5 μm）。灵敏度分析也提供了一个指导，在制造。一般情况下，发现GARC耦合器的垂直尺寸需要仔细控制，而水平尺寸则不那么关键。
A grating-assisted-cylindrical-resonant-cavities (GARC) interlayer coupler made of Si/SiO2 is designed and simulated to achieve efficient and broadband interlayer coupling. This coupler consists of three cylindrical resonant cavities: two waveguide cavities in the horizontal direction and one cylindrical via cavity in the vertical direction. The resonant strengths of the two cylindrical waveguide cavities are enhanced by circular Bessel-function-defined gratings and distributed Bragg reflectors. The interlayer coupling efficiency of this Si/SiO2 GARC coupler is simulated as ηc=68%(-1.7 dB) for transverse electric polarization at 1.55 μm wavelength, which is generally higher than those of conventional rectangular silicon-on-insulator gratings with additional features such as reflectors, overlayers, chirped periods, dual gratings, etc. The GARC couplers are predicted to have favorable attributes compared to previous couplers, including wider operational bandwidth (δλ,1 dB=270 nm), larger tolerance to inplane misalignment (±2 μm for 1 dB extra loss), easier grating patterning (wider grating ridges), smaller footprint (20 μm in diameter), and more flexible choices of interlayer distances (2-5 μm). A sensitivity analysis is also provided as a guide in fabrication. In general, it is found that the vertical dimensions of the GARC couplers need to be carefully controlled while the horizontal dimensions are less critical.