Coherent ultrafast pulse synthesis between an optical parametric oscillator and a laser

We have demonstrated coherent pulse synthesis between the carrier-envelope, phase-locked, second-harmonic pulses from a synchronously pumped femtosecond optical parametric oscillator and those from its self-mode-locked Ti:sapphire pump laser. By using a single nonlinear crystal for parametric and second-harmonic generation, we maximized the common-mode rejection of environmental noise, obtaining a temporal overlap between the pulses with a precision of 30 as (1% of the optical period) in an observation time of 20 ms. Mutual coherence between the two parent pulses was verified optically by spectral interferometry, and synthesis was tested by measuring the autocorrelation of the combined pulses, with and without carrier-envelope phase locking.