Mj. Guy et al., GENERATION OF FEMTOSECOND SOLITON PULSES BY PASSIVE-MODE LOCKING OF AN YTTERBIUM ERBIUM FIGURE-OF-8 FIBER LASER, Optics letters, 18(17), 1993, pp. 1447-1449
250-fs pulses have been generated directly from a passively mode-locke
d ytterbium-erbium figure-of-eight laser. In addition to the usual cha
racteristic of one pulse per round trip, the laser could be made to pr
oduce regular pulse bursts at the round-trip frequency, with repetitio
n rates in excess of 300 GHz.