Patent ID: 7940816

Claim:
A mode-locked, polarization-maintaining figure-eight fiber laser for generating ultrashort optical output pulses, the laser comprising a bi-directional loop comprising a section of polarization maintaining optical fiber; a unidirectional loop comprising a section of polarization maintaining optical fiber; a first section of a polarization-maintaining amplifying medium inserted along the polarization maintaining optical fiber forming either one of the bi-directional loop and the unidirectional loop, the amplifying medium responsive to an incoming optical pump signal introduced to the fiber laser through an optical coupler, the incoming optical pump signal used to generate an amplified version of a propagating optical signal; a polarization maintaining directional coupler disposed between and coupled to both the bi-directional and unidirectional loops of polarization maintaining optical fibers, the maintained polarization state of the propagating optical signal providing a stable and constant mode-locking state thereof; and an optical loss element in the bi-directional loop to introduce optical bias by creating an accumulation of a phase difference between a plurality of optical signals circulating within the bi-directional loop sufficient to generate an ultrashort optical output pulse therefrom and having an additional flexibility in tuning the bias of the bi-directional loop for a given cavity configuration.