We generate high harmonics in a few mm long 200-300 mbar argon cell, driven by coherent superposition among the outputs of two different spectral channels of a parametric waveform synthesizer . The NIR channel delivers ~6 fs pulses at 800 nm, while the IR channel delivers ~10 fs pulses at 1.8 μm. The CEP of both pulses is stabilized and controlled, and the relative phase (delay) between them is measured, actively stabilized and controlled as well . We performed a relative delay scan with fixed CEPs while observing HHG. Given the phase-matching condition the HHG is predominantly driven by the NIR-channel, while the IR-channel acts as a ”perturbation” to the generation process.
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