Ultra-broadband fiber optical parametric amplifier pumped by chirped pulses.

We numerically and experimentally demonstrate ultra-broadband fiber optical parametric amplification in a microstructured fiber pumped by stretched short pulses. The chirped pump pulse induces a temporally spread spectral gain suitable for optical parametric chirped pulse amplification in fibers. Numerical simulation shows ~45  dB flat gain with more than 70 nm bandwidth, allowing sub-35 fs pulse amplification around 1 μm with reduced gain narrowing. This amplification principle is experimentally confirmed by measuring the instantaneous spectral gain band and related chirp.