Inverse design and demonstration of an ultracompact broadband dual-mode 3 dB power splitter

An ultracompact broadband dual-mode 3 dB power splitter using inverse design method for highly integrated on-chip mode (de) multiplexing system is proposed and experimentally demonstrated. A dual-mode convertor based on subwavelength axisymmetric three-branch waveguide is utilized to convert TE0 and TE1 to three intermediate fundamental modes. The axisymmetric topology constraint of the nanostructures enables the optimized device to achieve a strict 50:50 splitting ratio over a broad wavelength range from 1.52 to 1.60 mu m. The fabricated device occupied a compact footprint of only 2.88 mu m x 2.88 mu m. The measured average excess losses and crosstalks for both modes were respectively less than 1.5 dB and -20 dB from 1.52 to 1.58 mu m for both TE0 and TE1, which arc consistent with the numerical simulations. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement