Patent ID: 8144737

Claim:
A fiber laser for generating light pulses having an adjustable pulsewidth, the fiber laser comprising: a laser cavity comprising optical fiber arranged in a figure-of-eight configuration defining a non-reciprocal loop having a propagation direction therein and a reciprocal loop having opposite propagation directions therein, said laser cavity further comprising a main coupler interconnecting said loops; a gain medium provided in said reciprocal loop at an asymmetrical position with respect to the main coupler selected so that said light pulses counter-propagating within said reciprocal loop have a phase relationship at the main coupler favoring coupling into the propagation direction of the non-reciprocal loop; a pump source coupled to the reciprocal loop for launching a pump light beam in the gain medium, the pump light beam having a pump power value; pump control means for controlling the pump power value of the pump source within a range extending above an operational lasing threshold of the laser cavity, wherein changing the pump power value of the pump source within said range changes the pulsewidth of the light pulses without modifying a peak power of said light pulses.