光誘起相転移を用いたプラズモニック構造・光導波路による超高速全光変調器

前一年，实现了三个关键目标。首先，完成了一套独特的微泵探测光谱分析装置。该装置具有将超短激光脉冲注入光子集成电路并测量其时间分辨响应的能力。使用空间滤波系统，该装置还可以将输出的信号与光子集成电路的特定元件隔离。其次，研究了VO2薄膜在超短激光脉冲激励下的恢复动力学。发现了一个中等注量区，在那里VO2经历了绝缘体-金属的完全转变，同时仍表现出亚ns的恢复，从而首次证实了VO2具有以GHz速度调制的潜力。最后，研究了NbO_2薄膜在超短激光脉冲激励下的光致调制，并详细分析了响应的唯象来源。研究发现，如果对散热进行适当的管理，NbO2有可能以高达太赫兹的速度进行调制。在此基础上，编写了两篇期刊论文。其中一篇发表于2019年12月(J.Kenji Clark等人，Phys.Rev.Res.1,033168(2019年))，另一个目前正在美国计算机学会光子学杂志上进行审查。

In the previous year, three key objectives were achieved. First, a unique micro-pump probe spectroscopy setup was completed. The setup has the capability of injecting ultrashort laser pulses into photonic integrated circuits and measuring their time-resolved response. Using a spatial filtering system, the setup can also isolate signals output from specific elements of a photonic integrated circuit. Second, the recovery dynamics of VO2 thin films after excitation by an ultrashort laser pulse were studied. A mid-fluence region where VO2 undergoes a full insulator-metal transition while still exhibiting sub-ns recovery was discovered, thus verifying for the first time that VO2 has the potential to be modulated at GHz speeds. Finally, the photo-induced modulation of NbO2 thin films after excitation by an ultrashort laser pulse was studied and the phenomenological origins of the response was examined in detail. It was found that NbO2 has the potential to be modulated at up to THz speeds given proper management of heat dissipation. Based on this work two journal articles were compiled. One was published in December of 2019 (J. Kenji Clark et al., Phys. Rev. Res. 1, 033168 (2019)) and the other is currently under review in ACS Photonics.