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Nonlinearity in terahertz photon physics

APSE2010 Osaka, Japan. June 15, 2010. Nonlinearity in terahertz photon physics. Masaya NAGAI Dep. Physics, Kyoto Univ. Janan PRESTO, JST, Japan. Colleague. M. Jewariya, H. Hirori, K. Tanaka (Kyoto Univ.) I. Ichikawa, H. Ohtake, T. Sugiura, Y. Uehara (Aishin seiki)

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Nonlinearity in terahertz photon physics

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  1. APSE2010 Osaka, Japan June 15, 2010 Nonlinearity in terahertz photon physics Masaya NAGAI Dep. Physics, Kyoto Univ. Janan PRESTO, JST, Japan

  2. Colleague M. Jewariya,H. Hirori, K. Tanaka (Kyoto Univ.) I. Ichikawa, H. Ohtake, T. Sugiura, Y. Uehara (Aishin seiki) I. Katayama, H. Aoki, J. Takeda (Yokohama National Univ.) H. Shimosato, M. Ashida, R. Kinjo, I. Kawayama, M. Tonouchi (Osaka Univ.)

  3. Outlines • Intense THz field governs material properties non-collinear optical rectification with LiNbO3 • nonlinear spectroscopy in THz frequency region Vibrational mode in amino-acid microcrystal and SrTiO3 e-h system in semiconductors Orientational motions in water • Summary

  4. Material Science in THz region Intramolecular vibration X-ray difraction e e 1 1 Intermolecular vibration Electric transition Orientational motion e Plasma motion e e 2 2 m m m 1m 100mm 10mm 1mm 100nm 10nm 1nm 0.1nm 100 m 10 m 1 m FIR NIR UV microwave MIR X-ray X g g 線 線 visble Soft mode in dielectric material Superconductor gap …..

  5. ps timescale of damping t in materials 4p D rot H = Jcond + ct Photonics (transition between quantum levels) Electronics (LCR, diode, etc) s0 ne2/me0 s(w) = c(w) = 1-iwt wT2-w2-iw/t Typical timescale of damping t in solids is ps. Intense monocycle THz pulse can be assume as as intense quasi-DC field Impulsive force with lowest center frequency

  6. Intense THz pulse generation with tilted pulsefront excitation THz pulse EO crystal (Mg: LiNbO3) Tilted pulsefront Excitation pulse 10mJ vgrcos q = vTHz Review: Hebling et al. J. Opt. Soc. Am. B 25, B6 (2008)

  7. Intense THz pulse in Kyoto Univ. Output power 0.6 mJ Maximum filed 249 kV/cm Jewariya, MN, et al., JOSAB 26, A101 (2009).

  8. Cascaded c(2) process enhances generation efficiency Excitation pulse Phase modulation THz pulse Optical rectification EO crystal IMRA AMERICA FCPA mJewel D1000 Wavelength: 1045nm Output power: 1W 10mJ Repetition: 100kHz Duration: 600fs MN et al. Opt. Express, 17 11543 (2009).

  9. Large amplitude vibration driven with intense THz pulse Vibrational potential has anharmonicity, and large-amplitude vibrational motions (climbing higher excited levels) brings in dissociation, which is decisive for chemical reaction and phase transition. Using intense THz pulse resonant for vibrational modes, we can coherently drive large amplitude vibrational motions

  10. Nonlinear medium: L-Arginine L-Arginine: amino-acid molecules L-Arginine microcrystal has the intermolecular vibration mode at 1 THz. kBT Population Jewariya, MN, Tanaka , submitted

  11. Time profile of Electric pulse passed through the arginine pellet X1/2 Jewariya, MN, Tanaka , submitted

  12. Ladder climbing in anharmonic potential Above 10 steps Ladder climbing Large E(w) small E(w) Jewariya, MN, Tanaka , submitted

  13. Coherent processes in several levels system P=Tr[mr] Two level system: Casperson, PRA 57, 609 (1998). rn+2 n+2 0.02 0.5 mE0/h=1 3 kV/cm 25 kV/cm 100 kV/cm nn+1,n+2 rn+1 n+1 nn,n+1 rnn nn-1,n rn-1 n-1

  14. Hardening of softmodein SrTiO3 thin film kBT Katayama MN et al. CLEO/QELS 2010

  15. probe optical pulse MQWs THz pump pulse at 10 K THz pump-vis probe spectroscopy in ZnSe MQW system Hirori, MN, Tanaka, PRB 81, 081305(R) (2010). V reh nB=1 Exciton resonance disappears with blue shift Eex/eaB = 70 kV/cm

  16. THz motions of WATER Dielectric tensor Huge orientational relaxation mode, related to hydrogen bonding network, lies in THz frequency region. Raman tensor at low frequency is little, so it is difficult to drive water molecules via Raman induced Kerr effect. Raman tensor Fukasawa et al. PRL 95, 197802 (2005)

  17. Single THz pulse responses of water Response of water in 100mm silica cell MN and Tanaka CLEO/QELS 2010

  18. Temporal evolution of dielectric constant of water (c) MN and Tanaka CLEO/QELS 2010

  19. Driving orientational motion of water Even with sub-mW injection, temperature of orientational motion increase a few tens K. Rotational motion is driven without thermal relaxation (or before heating other modes) Yada, MN, Tanaka, CPL (2008).

  20. Hydrogen bonding network controlled with THz pulse We can control water properties as SOLVENT in ps timescale, which influence chemical reactions of solute molecules. MN and Tanaka CLEO/QELS 2010

  21. Summary • We succeed intense THz pulse generation with >200 kV/cm field amplitude. • We demonstrate THz nonlinearity of vibration modes in amino acide microcrystal and dielectric materials. Experimental results is interpreted with ladder climbing in anharmonic potential. • We demonstrate huge spectrum modulation near the bandgap of semiconductors with intense THz pulse, which shows non-perturbed nonlinear regime. • We observe water molecules driven by intense THz pulses. This motions is different from thermal effects. Results show the reorientational motion of water molecules with breaking hydrogen bonding in several picosecond timescale.

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