Study on carrier dynamics of transition metal oxides using broadband infrared pump-probe spectroscopy

利用宽带红外泵浦探针光谱研究过渡金属氧化物的载流子动力学

• 批准号: 16340091
• 负责人: ASHIDA Masaaki
• 金额: $ 10.62万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16340091/
• 关键词: THz time-domain spectroscopy; pump-probe spectroscopy; ultra short pulse laser; photoconductive antenna; transition metal oxide; infrared spectroscopy; carrier dynamics; ポンプ-プローブ分光

1. We investigated ultrabroadband detection of terahertz electric field with a dipole-type photoconductive (PC) antenna with 10 fs pulse laser. Ultrabroadband frequency response from 0.1 THz up to 100 THz was demonstrated using two types of generation methods: optical rectification using a thin GaSe crystal and dipole radiation using a PC antenna with a large aperture. Comparison between the spectrum obtained with the PC antenna and the calibrated one with a combination of a monochromator and an MCT detector suggests that PC antenna detection has potential for detecting a frequency region much higher than 100THz.2. We utilized rapid scanning method to ultrabroadband terahertz detection using photoconductive antennas. Measurement time was reduced to one tenth of the conventional method. Ultrabroadband terahertz spectrum from 0.1 to 15 THz was observed. This technique provides significant improvement in THz timedomain spectroscopy.3. We measured transmittance of SrTiO_3 thin films deposited on MgO in broadband THz region from 0.1 THz to 10THz. Then we calculated the complex dielectric constant of the thin films directly from amplitude and phase of the transmittance. At room temperature, broad soft-mode (TO1) dispersion is observed around 3 THz and TO2 mode at 5 THz. The resonant frequencies of both modes are almost independent of the thickness at room temperature. On the other hand, at cryogenic temperature (15K), dielectric dispersion is strongly dependent on the thickness. The previously reported softening of the SrTiO_3 thin films deposited on SrRuO_3 substrate is similar to the obtained one. This fact indicates the existence of the intrinsic size effect in SrTiO_3 thin films, since the softening is independent of the substrate. However, the broadening is only observed in extremely thin films deposited on MgO, suggesting that the strain from the substrate strongly affects the width of the soft mode dispersion.

1. 我们研究了采用偶极型光电导（PC）天线和 10 fs 脉冲激光的太赫兹电场超宽带检测。使用两种类型的生成方法演示了从 0.1 THz 到 100 THz 的超宽带频率响应：使用薄 GaSe 晶体的光学整流和使用大孔径 PC 天线的偶极辐射。通过 PC 天线获得的频谱与通过单色仪和 MCT 检测器组合获得的校准频谱之间的比较表明，PC 天线检测具有检测远高于 100THz 的频率区域的潜力。2。我们利用快速扫描方法使用光电导天线进行超宽带太赫兹检测。测量时间缩短至传统方法的十分之一。观察到0.1至15 THz的超宽带太赫兹光谱。该技术显着改进了太赫兹时域光谱。3．我们测量了沉积在 MgO 上的 SrTiO_3 薄膜在 0.1 THz 至 10 THz 的宽带太赫兹区域的透射率。然后我们直接根据透射率的幅度和相位计算薄膜的复介电常数。在室温下，在 3 THz 附近观察到宽软模式 (TO1) 色散，在 5 THz 处观察到 TO2 模式色散。两种模式的谐振频率几乎与室温下的厚度无关。另一方面，在低温 (15K) 下，介电色散强烈依赖于厚度。先前报道的沉积在 SrRuO_3 基底上的 SrTiO_3 薄膜的软化与所获得的类似。这一事实表明 SrTiO_3 薄膜中存在固有尺寸效应，因为软化与基材无关。然而，仅在沉积在 MgO 上的极薄薄膜中观察到展宽，这表明来自基底的应变强烈影响软模色散的宽度。

项目成果

Sensitivity of Photoconductive Antenna for Ultrabroadband Terahertz Radiation : Feasibility of detection over 100THz

光电导天线对超宽带太赫兹辐射的灵敏度：检测超过 100THz 的可行性

• 发表时间: 2005
• 期刊: International Quantum Electronics Conference 2005 and the Pacific Rim Conference on Laser and Electro-Optics 2005 (IQEC/CLEO-PR), Technical Digest
• 作者: 伊藤;山口;渡部;M.Ashida
• 通讯作者: M.Ashida

Four-wave mixing and direct terahertz emission with two-color semiconductor lasers

• DOI: 10.1063/1.1737486
• 发表时间: 2004-04
• 期刊: Applied Physics Letters
• 影响因子: 4
• 作者: S. Hoffmann;M. Hofmann;E. Bründermann;M. Havenith;M. Matus;J. Moloney;A. S. Moskalenko;M. Kira;S. W. Koch;S. Saito;K. Sakai

物質・現象・新技術(3)強相関電子系

材料、现象与新技术（3）强相关电子系统

• 发表时间: 2005
• 期刊: オプトロニクス 279
• 作者: S.Miyauchi;Y.Watanabe;芦田昌明
• 通讯作者: 芦田昌明

Polarity reversal of the magnetic field induced component of terahertz radiation from InAs surfaces at high density excitation

高密度激励下 InAs 表面太赫兹辐射磁场感应分量的极性反转

• 发表时间: 2004
• 期刊: Appl. Phys. Lett. 85
• 作者: N.Bulut;H.Matsueda;T.Tohyama;S.Maekawa;M.Nakajima
• 通讯作者: M.Nakajima

Terahertz radiation from coherent confined optical phonons in GaAs/AlAs multipule quantum wells

GaAs/AlAs 多量子阱中相干受限光学声子的太赫兹辐射

• 发表时间: 2007
• 期刊: phys. stat sol. (a) 204
• 作者: S.E.Barnes;J.Ieda;S.Maekawa;Y.Matsuo;M.Nakayama
• 通讯作者: M.Nakayama