@article{1205, author = {R. Jones and Jun Ye}, title = {High-repetition-rate coherent femtosecond pulse amplification with an external passive optical cavity}, abstract = {We demonstrate a general technique for enhancement of femtosecond pulses from a pulse train through their coherent buildup inside a high-finesse cavity. Periodic extraction of the intracavity pulse by means of a fast switch provides a net energy gain of 42 to >70 times for 38–58-fs pulse durations. Starting with an actively stabilized but otherwise standard mode-locked laser system, we demonstrate pulses of >200-nJ energy. © 2004 Optical Society of America}, year = {2004}, journal = {Optics Letters}, volume = {29}, pages = {2812}, month = {2004-12}, issn = {0146-9592}, doi = {10.1364/OL.29.002812}, }