We describe a new fiber laser configuration based on a nonlinear optical lo
op mirror with a symmetrical coupler, a quarter-wave retarder, and highly t
wisted, birefringent, fiber in the loop. The nonlinear optical loop mirror
configuration operates by nonlinear polarization rotation. We have achieved
stable generation of subpicosecond pulses with milliwatts of average outpu
t power, (C) 2001 Optical Society of America.