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High harmonic generation (HHG) is one of the approaches to reach attosecond time scale. Selecting cut-off region in the spectrum of HHG is important because it includes an isolated attosecond optical pulse. However it would be more difficult to generate HHG from the molecules with a relatively lower ionization potential. Here we demonstrate that the HHG from molecules can be controlled using a transient lens method. By changing curvature of the transient lens produced by compressed laser pulses (~6fs), we scan over the photon energy of HHG from the lower harmonics to the cut-off region. The continuum spectrum of HHG from N2 or D2 in the cut-off region is selected. We also show the present status of the carrier-envelope phase (CEP) stabilized, high average power laser system for JST project in Ottawa. The system can generate the 1KHz repetition rate laser pulses with an output power of 2.3mJ in the pulse duration of 35fs with CEP stabilization. The CEP can be stabilized over few hours. |
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