Parra Jorge, Hurtado Juan, Griol Amadeu, Sanchis Pablo
Opt Express. 2020 Mar 30;28(7):9393-9404. doi: 10.1364/OE.386959.
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 π phase shift of 10 mW and switching time of a few microseconds for a 50 µm 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.
通常，诸如金属之类具有大光学损耗的材料被用作基于硅的热光相移器的微加热器。因此，加热器必须放置在远离波导的位置，这可能会以相移器性能为代价。减小波导与加热器之间的间隙可以降低功耗或提高开关速度。在这项工作中，我们提出了一种用于热光调谐的超低损耗微加热器，通过使用诸如氧化铟锡（ITO）之类的与CMOS兼容的透明导电氧化物，目的是大幅减小间隙。使用有限元方法模拟，针对不同的包层配置以及TE和TM偏振，对基于ITO和Ti的加热器进行了比较。此外，所提出的基于ITO的微加热器也已采用最佳间隙和包层配置制造出来。实验结果表明，对于一个50 µm长的ITO加热器，实现π相移的功耗为10 mW，开关时间为几微秒。所获得的结果证明了使用ITO作为高性能硅热光调谐的超低损耗微加热器的潜力，并为实现新兴集成光子应用中所需相移器的大规模集成开辟了一条替代途径。
