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Exciton Engineering Laboratory by warwar123


									Exciton Engineering Laboratory
Laboratory Head: Teruya Ishihara (D.Sci.)

Key Sentence:Unconventional optical responses are studied in specially
designed nano-spatial arrangements.
Key Words:Exciton, plasmon, photonic crystal, inorganic-organic hybrid
semiconductor, optical nonlinearity

Purpose of Research:
In this laboratory, we study spatio-temporal pattern generation, optical nonlinearity, and
ultrafast luminescence and their application in exciton-(or plasmon-)in-the-nanostructure
systems from both experimental and theoretical point of view. In photonic crystals, which has
periodic structure of optical wavelength scale, we can spatially modulate electromagnetic waves
and control its interaction on elementary excitation in materials. Besides we can design such a
special sub-wavelength structure that its optical response has never existed in nature. By
forming thin film of semiconductors or metal on a substrate patterned by electron beam
lithography and dry etching techniques, we design various new material systems which exhibit
novel response.

                                             Incident angle dependence of photovoltage
                                             induced in Au thin film. Signal is enhanced
                                             upon resonant excitation of surface plasmon.

Research done in FY2005
Theme (Researchers)
1. Optical response in inorganic-organic hybrid semiconductors (J. Fujisawa and M. Shimizu)
Charge-transfer transition was analyzed in a one-dimensional inorganic-organic hybrid
semiconductor. Tri-exciton state was attributed for nonlinear emission in a two-dimensional
inorganic-organic hybrid semiconductor.

2. Photo-electric response of surface plasmon (A.S. Vengurlekar, S. Tikhodeev, N.A. Gippius, A.
Christ, X. Luo, C. Kamaga and T. Ishihara)
Photovoltage due to surface plasmon excitation by laser pulse was observed in prism-coupling

geometry. Similar effect was observed in metallic grating structure.

3. Photo-induced phase transition (J. Fujisawa)
In collaboration with Condensed Molecular Materials laboratory, photo-induced insulator-metal
transition was observed and studied.

4. Excitons in Cuprous Oxide (N. Naka)
Aiming for excitonic Bose condensation, growth technique of thin single crystal of cuprous oxide
was established.

5. Optical response in photonic crystals (X. Luo, J. Hayase, M. Iwanaga, C. Kamaga, Y.G. Roh
and Y. Segawa)
Novel photolithography technique based on localized electric field distribution of surface
plasmon was proposed and demonstrated. Photoluminescence dynamics was discussed for
two-dimensional photonic crystal infiltrated with inorganic-organic hybrid semiconductor.
Thermally induced photoresponse was desinged for photonic crystal infiltrated with liquid
crystal. Metamaterial structure with negative refractive index at near infrared was desinged.

6. Theory of optical response in photonic crystals (G.A. Gippius and S. Tikhodeev)
Numerical codes based on scattering matrix formalism were developed for dielectric and
metallic photonic crystals with arbitrary shape.

                                                    Crystal structure of (Methylviologen)
                                                    Pb2I3.Photoexcitation transfers electron
                                                    from PbI nano-wire to methylviologen.


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