Exploring extreme response of solids exposed to intense few-cycle mid-infrared electric fields

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H04816
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Optical engineering, Photon science
• Research Institution: The University of Tokyo
• Principal Investigator: Ishii Nobuihsa 東京大学, 物性研究所, 助教 (40586898)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 超高速赤外レーザー / 固体 / 非線形効果 / 高次高調波

Outline of Final Research Achievements

We have explored extremely nonlinear response of solid. We have developed an intense femtosecond laser in the mid-infrared region of the spectrum, allowing the application of more than 10 MV/cm electric fields in solids without optical damage. As a result, the response of electrons in solids exhibits extremely nonlinearity, generating high harmonics up to the ultraviolet region, which consist of comb-like spectral components that have integer multiple of the laser frequency. The polarization resolved study of the high harmonics directly allows us to determine the band curvature of the lowest conduction band of solids. In other experiments, we have demonstrated the selection rules in solid high harmonics generation experimentally for the first time. Additionally, we have detected the reflected high harmonics from solid interfaces, which reveals the propagation effect of intense mid-infrared pulses on high harmonic generation in solids.

Free Research Field

超高速レーザー開発とその応用

Academic Significance and Societal Importance of the Research Achievements

高強度電界下の物質応答やその絶縁破壊は、近年の高速エレクトロニクスやスイッチング、並びにリーク電流問題と密接にかかわっており、これからさらなる高速化が進む、情報社会基盤における先駆的な研究であると思われる。
また光学分野においても、紫外線領域では物質の屈折率が低く透過率が低いために、偏光光学素子を作成することが非常に困難である。極限的非線形光学効果を用いて赤外光源の制御と固体高調波発生媒質の人工構造成型により、紫外高調波の偏光制御が可能となり、紫外の分光実験への適応が可能となる。