Wang Mengke, Li Junhui, Yao Hao, Li Xuepeng, Wu Jieyun, Chiang Kin Seng, Chen Kaixin
Opt Express. 2022 Oct 24;30(22):39706-39715. doi: 10.1364/OE.474594.
It is essential to bias a thin-film lithium-niobate Mach-Zehnder electro-optic (EO) modulator at the desired operation condition to ensure optimal performance of the modulator. While thermo-optic (TO) control can solve the problem of bias drift, it consumes significant electric power. In this paper, we propose a technique to largely reduce bias power consumption by combining passive bias and TO bias. In our design, waveguide sections with different widths are introduced in the two arms of the MZ modulator to produce a desired phase difference of π/2 rad (the desired operation condition), and local heating with electrode heaters placed on the waveguides is employed to provide compensation for any phase drift caused by fabrication errors and other effects. As the TO control only serves to compensate for small errors, the electric power required is low and the response is fast. To demonstrate our technique experimentally, we fabricate several modulators of the same design on the same chip. Our experimental modulators can operate up to ∼40 GHz with a half-wave voltage of ∼2.0 V over a wide optical bandwidth, and the performances are insensitive to ambient temperature variations. The TO bias powers required range from 1 mW to 15 mW, and the thermal rise and fall times are 47 µs and 14 µs, respectively. Our technique can facilitate the development of practical high-speed EO modulators on the lithium-niobate-on-insulator platform.
在期望的工作条件下对薄膜铌酸锂马赫-曾德尔电光（EO）调制器进行偏置，对于确保调制器的最佳性能至关重要。虽然热光（TO）控制可以解决偏置漂移问题，但它会消耗大量电力。在本文中，我们提出了一种通过结合无源偏置和TO偏置来大幅降低偏置功耗的技术。在我们的设计中，在MZ调制器的两个臂中引入不同宽度的波导段，以产生π/2 rad的期望相位差（期望的工作条件），并采用放置在波导上的电极加热器进行局部加热，以补偿由制造误差和其他效应引起的任何相位漂移。由于TO控制仅用于补偿小误差，所需的电力较低且响应速度快。为了通过实验证明我们的技术，我们在同一芯片上制造了几个相同设计的调制器。我们的实验调制器在宽光学带宽上可以在高达约40 GHz的频率下工作，半波电压约为2.0 V，并且性能对环境温度变化不敏感。所需的TO偏置功率范围为1 mW至15 mW，热上升和下降时间分别为47 μs和14 μs。我们的技术可以促进绝缘体上铌酸锂平台上实用高速EO调制器的开发。
