The thermal lensing effect in transparent (linear and nonlinear) molecular liquids can be modulated by disrupting continuously output 82 MHz 28 fs laser pulses at 800 nm to form trains of various widths ( t ) with respect to the thermal diffusivity time th ($ 2 ms). We present nonlinear refraction results for CHBr 3 (bromoform) obtained by the Z -scan technique. The results show that the thermal lensing effect increases with t when t is less than th , but becomes steady when t exceeds th and reaches 30 ms. The proposed technique of modulating the thermal lensing effect by varying t has great application potential in information photonics and optoelectronic devices, such as variable optical attenuators, holographic recording media, optical limiters and optical switches.

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