A High-Efficiency Nonuniform Grating Coupler Realized With 248-nm Optical Lithography

作者：He Li^*; Liu Yang; Galland Christophe; Lim Andy Eu Jin; Lo Guo Qiang; Baehr Jones Tom; Hochberg Michael

来源：IEEE Photonics Technology Letters, 2013, 25(14): 1358-1361.

DOI：10.1109/LPT.2013.2265911

• Grating coupler
• silicon photonics
• silicon waveguide

We describe a high-efficiency grating coupler (GC) fabricated on a silicon-on-insulator wafer with 220 nm top silicon layer. One single 60 nm shallow etch is required to define the diffractive gratings with a minimum lithographic feature size of 180 nm, which is within the limitation of 248 nm deep ultraviolet lithography. The measured average insertion loss is 3.1 +/- 0.2 dB similar to 1550 nm with a 1 dB bandwidth of 41 +/- 4 nm for TE polarization, whereas the best device exhibits 2.7 dB loss. The measured GC backreflection loss is better than 17 dB across the wafer. Cross-wafer data shows good uniformity and tolerance to fabrication variations. This is the best result reported for the commonly used 220 nm thickness Si that uses only a shallow etch step.

• 出版日期2013-7-15