Coupling loss occurs between a standard single-mode fiber and a silica waveguide when the difference between the refractive indices of the core and the cladding of the silica waveguide is high. We designed a Y-branch structure for use as a spot-size converter to reduce this coupling loss. The structure was tested with a three-dimensional beam-propagation method and was shown to exhibit a significantly reduced coupling loss, a low polarization-dependent loss, and a good tolerance of imprecision in fabrication. No additional fabrication steps are required for this proposed spot-size converter.
© 2004 Optical Society of America
Qian Wang, Jianjun He, and Sailing He, "Y-Branch Spot-Size Converter for a Buried Silica Waveguide with Large Index Difference," Appl. Opt. 43, 3315-3318 (2004)