Compact and low-loss 1 x 3 polarization-insensitive optical power splitter using cascaded tapered silicon waveguides

In this Letter, a 1 x 3 polarization-insensitive optical power splitter based on cascaded tapered silicon wave-guides is proposed and experimentally demonstrated on a silicon-on-insulator platform. By utilizing the particle swarm optimization algorithm and the finite difference time domain method, the structural parameters of the coupling regions are carefully designed to achieve polarization-insensitive property, compact size, low insertion loss, high uniformity, and broad bandwidth. The coupling length can be as short as 7.3 mu m. Our measurement results show that, at 1550 nm, the insertion losses of the fabricated device operating in transverse electric (TE) and transverse magnetic (TM) polarizations are, respectively, 0.068 dB and 0.62 dB. Within a bandwidth from 1525 to 1575 nm, the insertion loss is lower than 0.82 dB and the uniformity is less than 1 dB for the fabricated device operating in TE polarization, while the fabricated device operating in TM polarization can have an insertion loss smaller than 1.50 dB and a uniformity lower than 1 dB from 1528 to 1582 nm. (C) 2020 Optical Society of America