Abstract
In the ultrafast optics field, quasi-single carrier cycle pulse can apply to high order harmonic generation to induce isolated attosecond pulse and other relative technical applications. The transform limited (TL) pulse in visible-to-near infrared band can just reach the near single optical cycle. Up to now, there have been developed several ways to characterize these pulses, such as attosecond streaking, polarization-gating cross-correlation frequency-resolved optical gating (PG-XFROG), second harmonic generation dispersion-scan (SHG D-scan), and so on. Originally, we use modified interferometric field autocorrelation (MIFA) to characterize the near single cycle pulse with octave-spanning spectral range (rough 450 nm ~ 920 nm), which is generated by multiple-plates continuum (MPC) method. In the experiment, we apply 4f pulse shaper for giving the well-known spectral phase to the TL MPC and creating pulse replica with assigned delays, and then use 10 m BBO crystal to get an incomplete SHG spectrogram. Based on previous MIFA theory, it claims that selecting any one pair of two nearby SHG frequency traces can completely retrieve the pulse information; however, we find the small conclusion may be wrong according to the result of this experiment and simulation. The selected two nearby traces had better approach the SHG frequencies of the arithmetic mean of fundamental frequencies and we explain the result by the Fourier relation and SHG source in optics.