Generation of tunable narrowband pulses initiating from a femtosecond optical parametric amplifier

We report a tunable optical pulse expander capable of producing narrowband long pulses, starting from a femtosecond optical parametric amplifier (OPA), which is based on chirp-matched frequency mixing technique. The device delivers nJ-level pulses with bandwidth of ~0.1 nm and duration of ~45 ps within its tuning range from 1000 nm to 1090 nm. The combination of a femtosecond OPA and a pulse expander may provide synchronized and both tunable femtosecond and tens of picoseconds pulses simultaneously, which should be promising in the applications where both temporal and spectral resolutions are needed.