Tunable spectral interferometry for broadband phase detection by use of a pair of optical parametric amplifiers

We demonstrate tunable, single-pulse spectral phase measurement of broadband ultrafast signals by linear spectral interferometry. The approach is based on a coherently coupled pair of optical parametric amplifiers (OPAs). The first amplifier is the source of a signal pulse that is coupled into a nonlinear medium, where the pulse generates a broadband signal by nonlinear interactions; the second OPA provides a phase-correlated reference pulse that can be tuned across the broad spectral range and used for complete characterization of the broadband signal generated by the first OPA. An experimental demonstration of the technique for a nonlinearly modulated femtosecond pulse with a bandwidth of .200 nm occupying the range 1.13–1.36 mm is given. © 2005 Optical Society of America OCIS codes: 320.0320, 320.7100, 190.4970.