We present both theoretical and experimental results of an ultracompact waveguide coupler that is capable of highly efficient coupling of light from strip waveguides to slot waveguides, and vice versa. By optimizing the geometrical parameters, it is possible to achieve extremely low-loss coupling. A coupling efficiency of 97% has been obtained experimentally while keeping the overall size down to the range below 10 μm. Further analysis shows that the proposed coupler has relatively high tolerance to fabrication errors and is wavelength insensitive.
© 2009 Optical Society of America
Original Manuscript: February 20, 2009
Revised Manuscript: April 1, 2009
Manuscript Accepted: April 4, 2009
Published: May 4, 2009
Zhechao Wang, Ning Zhu, Yongbo Tang, Lech Wosinski, Daoxin Dai, and Sailing He, "Ultracompact low-loss coupler between strip and slot waveguides," Opt. Lett. 34, 1498-1500 (2009)