摘要
We retrieve intensity and phase profiles of 280 fs280 fs, 50 MHz50 MHz optical pulses with 124 aJ124 aJ coupled pulse energy (960 photons) by second-harmonic generation (SHG) frequency-resolved optical gating, using aperiodically poled LiNbO3LiNbO3 waveguides. The strong nonlinear interaction that is due to confinement within the micrometer-sized waveguide structure and the linearly chirped poling period contribute, respectively, to high SHG efficiency and broad phase-matching bandwidth. The achieved sensitivity is 2.7×10−6 mW22.7×10−6 mW2, improving on the previous record for self-referenced complete pulse characterization by 5 orders of magnitude.