Bindhu, C V; Harilal, S S; Nampoori, V P N; Vallabhan, C P G(Springer-Verlag, 2000)
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Abstract:
Optical limiting and thermal lensing studies are
carried out in C70–toluene solutions. The measurements are
performed using 9-ns pulses generated from a frequencydoubled
Nd:YAG laser at 532 nm. Optical limiting studies in
fullerene molecules lead to the conclusion that reverse saturable
absorption is the major mechanism for limiting. Analysis
of thermal lensing measurements showed a quadratic
dependence of thermal lens signal on incident laser energy,
which also supports the view that optical limiting in C70 arises
due to sequential two-photon absorption via excited triplet
state (reverse saturable absorption).
Santhi, A; Vinu V, Namboodiri; Radhakrishnan, P; Nampoori, V P N(American Institute of Physics, 2006)
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Abstract:
The authors apply the theory of photothermal lens formation and also that of pure optical nonlinearity to account for the phase modulation in a beam as it traverses a nonlinear medium. It is used to simultaneously determine the nonlinear optical refraction and the thermo-optic coefficient. They demonstrate this technique using some metal phthalocyanines dissolved in dimethyl sulfoxide, irradiated by a Q-switched Nd:YAG laser with 10 Hz repetition rate and a pulse width of 8 ns. The mechanism for reverse saturable absorption in these materials is also discussed.
Bindhu, C V; Harilal, S S; Nampoori, V P N; Vallabhan, C P G(Society of Photo-Optical Instrumentation Engineers, 1998)
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Abstract:
Thermal diffusivity measurements are carried out in certain organic liquids using the pulsed dual beam thermal lens technique. The 532 nm pulses from a frequency doubled Q-switched Nd:YAG laser are used as the heating source and an intensity stabilized He-Ne laser serves as the probe beam. Experimental determination of the characteristic time constant of the transient thermal lens signal is verified theoretically. Measured thermal diffusivity values are in excellent agreement with literature values.