Cohen Shany Zrihan, Singh Danveer, Nandi Sukanta, Lewi Tomer
Faculty of Engineering, Bar-Ilan University, Ramat-Gan 5290002, Israel.
Institute for Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002, Israel.
Nanophotonics. 2023 Jun 22;12(16):3217-3227. doi: 10.1515/nanoph-2023-0075. eCollection 2023 Aug.
Thermal effects are well known to influence the electronic and optical properties of materials through several physical mechanisms and are the basis for various optoelectronic devices. The thermo-optic (TO) effect, the refractive index variation with temperature (d/d), is one of the most common mechanisms used for tunable optical devices, including integrated optical components, metasurfaces, and nano-antennas. However, when a static and fixed operation is required, i.e., temperature invariant performance - this effect becomes a drawback and may lead to undesirable behavior through drifting of the resonance frequency, amplitude, or phase, as the operating temperature varies over time. In this work, we present a systematic approach to mitigate thermally induced optical fluctuations in nanophotonic devices. By using hybrid subwavelength resonators composed from two materials with opposite TO dispersions (d/d < 0 and d/d > 0), we are able to compensate for TO shifts and engineer nanophotonic components with zero effective TO coefficient (d /d ≈ 0). We demonstrate temperature invariant resonant frequency, amplitude, and phase response in meta-atoms and metasurfaces operating across a wide temperature range and broad spectral band. Our results highlight a path towards temperature invariant nanophotonics, which can provide constant and stable optical response across a wide range of temperatures and be applied to a plethora of optoelectronic devices. Controlling the sign and magnitude of TO dispersion extends the capabilities of light manipulation and adds another layer to the toolbox of optical engineering in nanophotonic systems.
热效应通过多种物理机制影响材料的电学和光学性质，是各种光电器件的基础。热光（TO）效应，即折射率随温度的变化（d/d），是用于可调谐光学器件（包括集成光学元件、超表面和纳米天线）的最常见机制之一。然而，当需要静态和固定操作时，即温度不变的性能时，这种效应就会成为一个缺点，并且随着工作温度随时间变化，可能会通过共振频率、幅度或相位的漂移导致不良行为。在这项工作中，我们提出了一种系统的方法来减轻纳米光子器件中热诱导的光学波动。通过使用由两种具有相反TO色散（d/d < 0和d/d > 0）的材料组成的混合亚波长谐振器，我们能够补偿TO偏移并设计出有效TO系数为零（d /d ≈ 0）的纳米光子组件。我们展示了在宽温度范围和宽光谱带内工作的超原子和超表面中温度不变的共振频率、幅度和相位响应。我们的结果突出了一条通往温度不变纳米光子学的道路，它可以在很宽的温度范围内提供恒定且稳定的光学响应，并应用于大量光电器件。控制TO色散的符号和大小扩展了光操纵的能力，并为纳米光子系统中的光学工程工具箱增添了新的内容。
