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Proceedings Paper

Ultrafast nonlinear optical response of polydiacetylenes
Author(s): Takayoshi Kobayashi; Masayuki Yoshizawa; Akio Yasuda
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Paper Abstract

Ultrafast optical response in several polydiacetylenes (PDAs) with different side-groups and morphologies has been investigated by femtosecond absorption spectroscopy. Several nonlinear optical processes, i.e., excitonic absorption saturation, hole burning, Raman gain, inverse Raman scattering, optical Stark effect, and induced-phase modulation, have been observed and the mechanisms are discussed. The relaxation from photoexcited free excitons to self-trapped excitons (STEs) has been observed in both blue- and red-phase PDAs. The time constant is estimated as 100 - 150 fs. The decay of STEs in the blue-phase PDAs is nearly exponential with time constant of about 1.5 ps at 290 K and about 2.0 ps at 10 K. The decay curve in the red-phase PDAs substantially deviates from exponential function. It is fitted phenomenologically to biexponential functions with time constants of slightly shorter than 1 ps and about 5 - 10 ps. These two time constants correspond to relaxations to the ground state, respectively, from the unthermalized (hot) STE and from the thermalized STE.

Paper Details

Date Published: 14 January 1993
PDF: 12 pages
Proc. SPIE 1774, Nonconducting Photopolymers and Applications, (14 January 1993); doi: 10.1117/12.139170
Show Author Affiliations
Takayoshi Kobayashi, Univ. of Tokyo (Japan)
Masayuki Yoshizawa, Univ. of Tokyo (Japan)
Akio Yasuda, Univ. of Tokyo (Japan)

Published in SPIE Proceedings Vol. 1774:
Nonconducting Photopolymers and Applications
Roger A. Lessard, Editor(s)

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