Hollow fiber for flexible sub-20-fs pulse delivery

Delivery of sub-20-fs pulses through 80 cm of a chirped photonic crystal fiber with chirped-mirror precompensation is experimentally demonstrated. The pulses out of the fiber are within 15% of the bandwidth limit and exhibit a pulse energy of 1 nJ. Peak powers amount to 50 kW directly out of the fiber. Measurements indicate a good pulse contrast with little satellite content. The combination of a specially designed hollow fiber with chirped mirrors sets a new record for the pulse durations directly delivered through a fiber.