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

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 ~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.


Published in:
IEEE Photonics Technology Letters, 25, 14, 1358-1361
Year:
2013
Publisher:
Institute of Electrical and Electronics Engineers
ISSN:
1941-0174
Laboratories:




 Record created 2017-12-01, last modified 2018-12-03


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