Broadband Polarization-insensitive Thermo-optic Switches on a 220-nm Silicon-on-insulator Platform

• Published in: IEEE photonics journal 2022-12, Vol.14 (6), p.1-7
• Main Authors: Li, Weijia, Xu, Luhua, Zhang, Jinsong, Mao, Deng, D'Mello, Yannick, Wei, Zixian, Plant, David V.
• Format: Article
• Language: English
• Subjects: Broadband; Broadband communication; C band; Heating systems; Insertion loss; Integrated optics; Mach-Zehnder interferometers; Metals; Optical interconnects; Optical polarization; Optical switches; Optical waveguides; Phase shifters; Polarization; Silicon; Silicon photonics; SOI (semiconductors); Switches; Thermo-optical devices; Waveguides
• ISSN: 1943-0655; 1943-0647
• DOI: 10.1109/JPHOT.2022.3218753

We demonstrate a polarization-insensitive 2 × 2 thermo-optic switch on a 220-nm silicon-on-insulator platform. This device is based on a balanced Mach-Zehnder interferometer with arms consisting of square-cross-section waveguides. In simulations, the Mach-Zehnder switch (MZS) exhibits extinction ratios (ERs) > 9.5 dB for the transverse electric (TE) and transverse magnetic (TM) polarized modes from 1500 nm to 1600 nm. Experimental results verify the broadband operation of the MZS: switching the two polarizations with ERs > 10 dB over an 85-nm wavelength range. Across the C-band (1530 \sim 1565 nm), the fabricated MZS has insertion losses of 0.2 \sim 4.3 dB and ERs > 16 dB (14 dB) at the cross (bar) port for both the TE and TM polarizations. The polarization-dependent losses are around 2 dB within a 100-nm wavelength range, showing the low polarization diversity of the MZS. The proposed MZS is a promising building block for implementing on-chip polarization-division-multiplexed optical interconnects.