Perturbed three-channel waveform synthesizer for efficient isolated attosecond pulse generation and characterization

Abstract

The generation of gigawatt-class isolated attosecond pulses (IAPs) is vital for attosecond pump-probe experiments. In such experiments, the temporal duration of IAPs must be determined quickly and accurately. In this study, we developed a perturbed three-channel waveform synthesizer for efficient IAPs generation and characterization at low repetition rates ( 10 Hz). Intense IAPs centered at photon energies of 60 eV (227 as duration) in Ar and 107 eV (128 as duration) in Ne were generated by the driving field from a three-channel waveform synthesizer and characterized using all-optical frequencyresolved optical gating (AO-FROG), which accelerated the measurement time to several minutes, providing fast feedback for the tunability of the IAP source. The peak power of the IAPs is higher than that reported in the literature.

Figures (4)

• Figure 1: (a) Calibrated accumulated supercontinuum intensity from Ar (red)/Ne (blue). Dash lines: without spectral filter; Solid lines: with metal filters. (b) Stability performance of the waveform synthesizer. CEP: 760 mrad rms; delay jitters: 47 as rms between signal and pump pulses; 18 as rms between signal and idler pulses.
• Figure 2: Results of gigawatts-scale extreme ultraviolet isolated attosecond pulses (IAPs) in Ar gas. (a) Measured AO-FROG trace. The lower curve shows the modulation of the intensity at 60 eV, and the fitting result (red). (B) Reconstructed trace with an RMS error of 1.89%. The lower black line shows the retrieved gating field. (c) Reconstructed IAP, black line: temporal intensity with a full width at half maximum (FWHM) duration of 227 as; blue dash line: temporal phase; red dash line: FTL pulse; black dot line: FROG-CRAB result. (d) Reconstructed IAP spectrum, black line: spectral intensity; blue dash line: spectral phase; red line: measured spectrum.
• Figure 3: Gating-field intensity dependence of AO-FROG traces, with a gating-field intensity of (a) $7\times10^{12} \rm{W/cm^{2}}$ and (b) $9\times10^{10} \rm{W/cm^{2}}$. (c) simulated trace with $2\times10^{12} \rm{W/cm^{2}}$ intensity. (d) phase matching condition of different synthesized fields.
• Figure 4: Experimental result for IAPs generated in Ne gas centered at 107 eV. (a) Measured AO-FROG trace; (b) AO-FROG trace reconstructed using the least-squares generalized projection (LSGP) algorithm, with a reconstruction error of 2.52%; (c) Reconstructed IAP profile: black line, temporal intensity with a FWHM duration of 128 as; blue dash line, temporal phase; red dash line: FTL pulse. (d) Reconstructed IAP spectrum profile: black line, spectral intensity; blue dash line, spectral phase; red line: measured spectrum.