Abstract
We report on a compact, ultra-broadband, adiabatic 3 dB coupler using silicon-on-insulator (SOI) strip waveguides assisted by sub-wavelength gratings (SWGs). In our device, two tapered SWG-assisted SOI strip waveguides achieve an adiabatic mode evolution of the two lowest-order transverse electric modes, in a two-waveguide system, for broadband 3 dB power splitting. Theory predicts that the proposed coupler will operate from 1200 nm to 1700 nm. We have been able to measure the performance of a device with a 15 μm long mode evolution region that achieves even, broadband power splitting over the 185 nm wavelength range of our tunable laser with an imbalance of less than and with low average excess losses of .
© 2018 Optical Society of America
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