Mode-locked fiber laser based on narrowband optical spectral filtering and amplifier similaritons
First Claim
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1. A laser device based on mode locking, comprising a laser cavity that produces laser light in form of laser pulses, wherein the laser cavity includes:
- a fiber amplifier having a gain fiber section that exhibits an optical gain with a gain spectral bandwidth and operates to amplify laser pulses within the gain spectral bandwidth and to cause each laser pulse to increase a pulse duration and a pulse spectral width from entry of the gain fiber section to exit of the gain fiber section;
a saturable absorber coupled to receive output light from the fiber amplifier and operable to exhibit saturable absorption of light with the light intensity and to reduce the pulse duration and the pulse spectral width of each laser pulse; and
an optical spectral filter coupled to receive light from the saturable absorber and to further reduce the pulse duration and the pulse spectral width of each laser pulse, the optical spectral filter selectively transmitting light in a single narrowband while rejecting light outside the narrowband and configured to have a bandwidth for the narrowband that is sufficiently narrow to cause each laser pulse to be self similar after propagating through the fiber amplifier and to evolve into a parabolic pulse profile with respect to time at the exit of the fiber amplifier to effectuate mode locking that generates the laser pulses.
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Abstract
Implementations and examples of mode-locked fiber lasers based on fiber laser cavity designs that produce self-similar pulses (“similaritons”) with parabolic pulse profiles with respect to time at the output of the fiber gain media to effectuate the desired mode locking operation. An intra-cavity narrowband optical spectral filter is included in such fiber lasers to ensure the proper similariton conditions.
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Citations
38 Claims
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1. A laser device based on mode locking, comprising a laser cavity that produces laser light in form of laser pulses, wherein the laser cavity includes:
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a fiber amplifier having a gain fiber section that exhibits an optical gain with a gain spectral bandwidth and operates to amplify laser pulses within the gain spectral bandwidth and to cause each laser pulse to increase a pulse duration and a pulse spectral width from entry of the gain fiber section to exit of the gain fiber section; a saturable absorber coupled to receive output light from the fiber amplifier and operable to exhibit saturable absorption of light with the light intensity and to reduce the pulse duration and the pulse spectral width of each laser pulse; and an optical spectral filter coupled to receive light from the saturable absorber and to further reduce the pulse duration and the pulse spectral width of each laser pulse, the optical spectral filter selectively transmitting light in a single narrowband while rejecting light outside the narrowband and configured to have a bandwidth for the narrowband that is sufficiently narrow to cause each laser pulse to be self similar after propagating through the fiber amplifier and to evolve into a parabolic pulse profile with respect to time at the exit of the fiber amplifier to effectuate mode locking that generates the laser pulses. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for generating laser pulses based on mode locking, comprising:
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configuring a laser cavity for generating laser pulses to include a fiber amplifier having a gain fiber section that exhibits an optical gain with a gain spectral bandwidth, a saturable absorber coupled to receive output light from the fiber amplifier and an optical spectral filter coupled to receive light from the saturable absorber and to output filtered light to the fiber amplifier to cause each laser pulse to have a varying spectral width along an optical path within the laser cavity that reaches a maximum spectral width value at the exit of the fiber amplifier and a minimum spectral width value at the output of the optical spectral filter; and operating the optical spectral filter to selectively transmit light in a single narrowband while rejecting light outside the narrowband and to have a bandwidth for the narrowband that is sufficiently narrow to cause each laser pulse to be self similar after propagating through the fiber amplifier and to evolve into a parabolic pulse profile with respect to time at the exit of the fiber amplifier to effectuate mode locking that generates the laser pulses. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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24. A laser device based on mode locking, comprising a laser cavity that produces laser light in form of laser pulses, wherein the laser cavity includes:
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a ring optical path to form a closed ring to circulate the produced laser light in form of laser pulses along one circulation direction in the ring optical path; a fiber amplifier located in the ring optical path and configured to include a gain fiber section that exhibits an optical gain with a gain spectral bandwidth and operates to amplify laser pulses within the gain spectral bandwidth and to cause each laser pulse to increase a pulse duration and a pulse spectral width from entry of the gain fiber section to exit of the gain fiber section; a saturable absorber located in the ring optical path downstream from the fiber amplifier in the circulation direction and coupled to receive output light from the fiber amplifier and operable to exhibit saturable absorption of light with the light intensity and to reduce the pulse duration and the pulse spectral width of each laser pulse; an optical spectral filter located in the ring optical path downstream from the saturable absorber in the circulation direction and coupled to receive light from the saturable absorber and to further reduce the pulse duration and the pulse spectral width of each laser pulse, the optical spectral filter structured to selectively transmit light in a single narrowband while rejecting light outside the narrowband and configured to have a bandwidth for the narrowband that is sufficiently narrow to cause each laser pulse to be self similar after propagating through the fiber amplifier and to evolve into a parabolic pulse profile with respect to time at the exit of the fiber amplifier to effectuate mode locking that generates the laser pulses; and wherein the laser cavity and components inside the laser cavity are structured to exhibit normal dispersion at each location along the ring optical path within the laser cavity. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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Specification