TY - GEN
T1 - Ultrafast nonlinear optical response of polydiacetylenes
AU - Kobayashi, Takayoshi T.
AU - Yoshizawa, Masayuki
AU - Yasuda, Akio
PY - 1993/1/1
Y1 - 1993/1/1
N2 - 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.
AB - 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.
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M3 - Conference contribution
AN - SCOPUS:0027147551
SN - 0819409472
T3 - Proceedings of SPIE - The International Society for Optical Engineering
SP - 222
EP - 233
BT - Proceedings of SPIE - The International Society for Optical Engineering
PB - Publ by Int Soc for Optical Engineering
T2 - Nonconducting Photopolymers and Applications
Y2 - 20 July 1992 through 21 July 1992
ER -