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We introduce an ultra-thin attosecond optical delay line based on controlled wavefront division of a femtosecond infrared pulse after transmission through a pair of micrometer-thin glass plates with negligible dispersion effects. The time delay between the two pulses is controlled by rotating one of the glass plates from absolute zero to several optical cycles, with 2.5 as to tens of attosecond resolution with 2 as stability, as determined by interferometric self-calibration. The performance of the delay line is validated by observing attosecond-resolved oscillations in the yield of high harmonics induced by time delayed infrared pulses, in agreement with a numerical simulation for a simple model atom. This approach can be extended in the future for performing XUV-IR attosecond pump–probe experiments.

We report the generation of tunable high-repetition-rate picosecond pulses in the near-infrared at high average power with record conversion efficiency using single-pass optical parametric generation (OPG) and amplification (OPA) in MgO:PPLN, for the first time, to the best of our knowledge. By deploying a mode-locked Yb-fiber laser at 1064 nm providing 21 ps pump pulses at 80 MHz, and a cascade of two 50-mm-long MgO:PPLN crystals, we generate up to 8.3 W of total average output power at a conversion efficiency of 59% over a tunable range of 513 nm, across 1902–2415 nm, with a record threshold as low as 600 mW (7.5 nJ). The two-stage OPG-OPA scheme provides control over fine wavelength tuning and output spectral bandwidths, enabled by the independent control of phase-matching in each crystal. The OPG-OPA output exhibits high spatial beam quality and excellent passive power and central wavelength stability better than 0.9% rms and 0.1% rms, respectively, over 1 hour. The output pulses have a duration of ∼ 11 ps , with a 10 dB bandwidth of ∼ 350 nm at 2107 nm.