Ultra-low loss hybrid ITO/Si thermo-optic phase shifter with optimized power consumption

© 2020 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited" [EN] Typically, materials with large optical losses such as metals are used as microheaters for silicon based thermo-optic phase shifters. Consequently, the heater must be placed far from the waveguide, which could come at the expense of the phase shifter performance. Reducing the gap between the waveguide and the heater allows reducing the power consumption or increasing the switching speed. In this work, we propose an ultra-low loss microheater for thermo-optic tuning by using a CMOS-compatible transparent conducting oxide such as indium tin oxide (ITO) with the aim of drastically reducing the gap. Using finite element method simulations, ITO and Ti based heaters are compared for different cladding configurations and TE and TM polarizations. Furthermore, the proposed ITO based microheaters have also been fabricated using the optimum gap and cladding configuration. Experimental results show power consumption to achieve a pi phase shift of 10 mW and switching time of a few microseconds for a 50 mu m long ITO heater. The obtained results demonstrate the potential of using ITO as an ultra-low loss microheater for high performance silicon thermo-optic tuning and open an alternative way for enabling the large-scale integration of phase shifters required in emerging integrated photonic applications. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement Ministerio de Economía y Competitividad (TEC2016-76849); Generalitat Valenciana (PROMETEO/2019/123); Ministerio de Ciencia, Innovación y Universidades (FPU17/04224). Parra Gómez, J.; Hurtado Montañés, J.; Griol Barres, A.; Sanchis Kilders, P. (2020). Ultra-low loss hybrid ITO/Si thermo-optic phase shifter with optimized power consumption. Optics Express. 28(7):9393-9404. https://doi.org/10.1364/OE.386959 Komma, J., Schwarz, C., Hofmann, G., Heinert, D., & Nawrodt, R. (2012). Thermo-optic coefficient of silicon at 1550 nm and cryogenic temperatures. Applied Physics Letters, 101(4), 041905. doi:10.1063/1.4738989 Sun, J., Timurdogan, E., Yaacobi, A., Hosseini, E. S., & Watts, M. R. (2013). Large-scale nanophotonic phased array. Nature, 493(7431), 195-199. doi:10.1038/nature11727 Shen, Y., Harris,