Figure eight fiber laser for ultrashort pulse generation
First Claim
1. A mode-locked, polarization-maintaining figure-eight fiber laser for generating ultrashort optical output pulses, the laser comprisinga 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.
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Abstract
A polarization-maintaining figure eight (PMFE) fiber laser is configured to generate ultrashort (femtosecond) output pulses by intentionally inserting asymmetry (in the form of a phase bias) into the bi-directional loop of the fiber laser. The introduction of asymmetry (via an asymmetric coupler, splice, attenuator, fiber bend, multiple amplifying sections, or the like) allows for an accumulation of phase difference within the bi-directional loop sufficient to create modelocking and generate ultrashort output pulses.
37 Citations
13 Claims
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1. 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification