Browsing by Author "Pan, C-L"

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Coherent control of third-harmonic-generation by a waveform-controlled two-colour laser field
(2013-06-01)
Chen, W-J
;
Lin, R-Y
;
Chen, W-F
;
Lee, C-K
;
Pan, C-L
We investigate generation of the third harmonic (TH; lambda = 355 nm) signal by two-colour excitation (lambda = 1064 nm and its second harmonic, lambda = 532 nm) in argon gas, with emphasis on the influence of relative phases and intensities of the two-colour pump on the third-order nonlinear frequency conversion process. Perturbative nonlinear optics predicts that the TH signal will oscillate periodically with the relative phases of the two-colour driving laser fields due to the interference of TH signals from a direct third-harmonic-generation (THG) channel and a four-wave mixing (FWM) channel. For the first time, we show unequivocal experimental evidence of this effect. A modulation level as high as 0.35 is achieved by waveform control of the two-colour laser field. The modulation also offers a promising way to retrieve the relative phase value of the two-colour laser field.