Chirped-pulse-amplification seed source through direct phase modulation.

This work presents integration of a directly chirped laser source (DCLS) into a high-energy optical parametric chirped-pulse-amplification (OPCPA) system. DCLS is an all-fiber, chirped laser source that produces nanosecond, linearly chirped laser pulses at 1053 nm for seeding high-energy chirped-pulse-amplification systems. DCLS produces a frequency chirp on an optical pulse through direct temporal phase modulation. A 1-ns, linearly chirped pulse with a 3-nm bandwidth is produced by applying an ~1000-rad (300π) quadratic temporal phase. The chirped pulse is amplified to 76 mJ in an OPCPA system and compressed to close to its Fourier transform limit, producing an intensity autocorrelation trace with a 1.5-ps width.