[论文解读] An optical metamixer

Sheng Liu, Polina P. Vabishchevich+6 more|arXiv (Cornell University)|Oct 31, 2017

Advanced Fiber Laser Technologies参考文献 40被引用 91

一句话总结

本文展示了一种基于 GaAs 的介电质超表面的光学频率混频器，通过利用多种非线性过程，同时从两个飞秒级近红外脉冲产生十一种新频率。

ABSTRACT

A frequency mixer is a nonlinear device that combines electromagnetic waves to create waves at new frequencies. Mixers are ubiquitous components in modern radio-frequency technology and are widely used in microwave signal processing. The development of versatile frequency mixers for optical frequencies remains challenging: such devices generally rely on weak nonlinear optical processes and, thus, must satisfy phase matching conditions. In this work, we utilize a GaAs-based dielectric metasurface to demonstrate an optical frequency mixer that concurrently generates eleven new frequencies spanning the ultraviolet to near-infrared (NIR) spectral range. Our approach combines strong intrinsic material nonlinearities, enhanced electromagnetic fields, and relaxed phase-matching requirements, to allow seven different nonlinear optical processes to occur simultaneously. Specifically, when pumped by two femtosecond NIR pulses, we observe second-, third- and fourth-harmonic generation, sum-frequency generation, two-photon absorption induced photoluminescence, four-wave mixing, and six-wave mixing. Such ultracompact optical mixers may enable a plethora of applications in biology, chemistry, sensing, communications and quantum optics.

研究动机与目标

• 在光频段使用超表面演示紧凑型光学频率混频器。
• 利用强非线性和场增强来放松相位匹配约束。
• 在单一器件中实现多种非线性光学过程的同时发生。

提出的方法

• 使用基于 GaAs 的介电质超表面作为非线性光学介质。
• 用两个飞秒近红外脉冲泵浦超表面以驱动非线性过程。
• 观测并识别包括二次、三次、四次谐波产生、和频产生、双光子吸收诱导的光致发光、四波混频和六波混频等多种非线性效应。

实验结果

研究问题

• RQ1 在由两个飞秒级 NIR 脉冲泵浦时，单个基于 GaAs 的超表面器件能否通过多种非线性过程生成多种新频率？
• RQ2 在光学 metamixer 中可以同时诱导哪些非线性过程，以及可产生多少种不同的新频率？
• RQ3 固有非线性、场增强以及放松的相位匹配要求如何促成紧凑结构中的多过程频率生成？

主要发现

• 该超表面同时支持七种不同的非线性光学过程。
• 生成十一种从紫外到近红外的新的频率。
• 该装置利用材料本征强非线性和增强场来放松相位匹配，从而实现超紧凑的光学混频。