"Phase coherent generation of tunable visible femtosecond pulses"P. Baum, S. Lochbrunner, J. Piel, and E. Riedle
Opt. Lett. 28, 185 - 187 (2003)
Stable interference between the output of two noncollinearly phase matched optical parametric amplifiers seeded by separate white light continua is observed. This means that the tunable visible pulses have a well defined relative phase and the temporal jitter between them is less than 1 fs. The residual phase variations are due to fluctuations of the pump power.
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