title: Y-branch spot-size converter for a buried silica waveguide with large index difference.
abstract: 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.
authors.affiliation: Centre for Optical and Electromagnetic Research, State Key Laboratory of Modern Optical Instrumentation, Joint Laboratory of Optical Communications of Zhejiang University, Yu-Quan, 310027 Hangzhou, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Jianjun
authors.initials: J
authors.lastname: He
authors.forename: Sailing
authors.initials: S
authors.lastname: He