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WEOEI01 |
High-Power Terahertz Generation and Terahertz Nonlinear Spectroscopy | |
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Recent development of ultra-short pulse technologies allows us to drive large amplitude motion of electron and ion coherently. The intense terahertz (THz) pulse resonant with the vibration frequency is promising to drive vibrations more directly and in coherent manner. In the case of semiconductors, one may coherently control the electronic system in the sub-level structures of quantum structures with intense THz waves. We recently succeeded to generate intense terahertz pulses by Cherenkov scheme with tilted wave-front technique in the LiNbO3 crystal [1, 2]. The maximum electric field is now larger than 1 MV/cm, which ponderomotive energy is as large as 10 eV. The ponderomotive energy is strong enough to ionize bound electronic states in solids such as donors and accepters and easy to induce nonlinear optical effects in solids [3]. In this talk, we would like to review first the state of the art of the high-power THz-wave generation with femtosecond lasers including Cherenkov-scheme in non-linear crystals and air-plasma generation. Then we will focus recent results on THz nonlinear optical phenomena induced by THz electric field larger than 100 kV/cm in molecular crystals [4], semiconductors [5] and ferroelectric materials [6].
[1] J. Hebling, G. Almási, I. Z. Kozma, and J. Kuhl, 'Velocity matching by pulse front tilting for large-area THz-pulse generation ,' Opt. Express, vol.10, pp. 1161-1166, 2002. [2] H. Hirori, A. Doi, F. Blanchard, and K. Tanaka, 'Single-cycle THz pulses with amplitudes exceeding 1 MV/cm generated by optical rectification in LiNbO3,' Appl. Phys. Lett., vol. 98, pp. 091106-1-091106-3, 2011. [3] K, Tanaka, H. Hirori, and M. Nagai, "THz Nonlinear Spectroscopy of Solids", IEEE Transactions on Terahertz Science and Technology, 1, 301-312 (2011). [4] Mukesh Jewariya, Masaya Nagai, and Koichiro Tanaka, "Ladder Climbing on the Anharmonic Intermolecular Potential in an Amino Acid Microcrystal via an Intense Monocycle Terahertz Pulse", Phys. Rev. Lett., 105, 203003 (2010). [5] H. Hirori, K. Shinokita, M. Shirai, S. Tani, Y. Kadoya, and K. Tanaka, " Extraordinary Carrier Multiplication Gated by a Picosecond Electric Field Pulse," Nature Commun. 2, 594 (2011). [6] I. Katayama, H. Aoki, J. Takeda, H. Shimosato, M. Ashida, R. Kinjo, I. Kawayama, M. Tonouchi, M. Nagai, and K. Tanaka "Ferroelectric soft mode in a SrTiO3 thin film impulsively driven t,o the anharmonic regime using intense picosecond terahertz pulses", Phys. Rev. Lett. 108, 097401 (2012). |
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