All-normal-dispersion femtosecond fiber laser
First Claim
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1. A fiber laser for facilitating generation of femtosecond duration pulses comprises a gain fiber to increase the energy of a pulse in a laser cavity that is free of anomalous dispersion and whose dispersion elements inside said cavity consist only of elements with normal group velocity dispersion, said cavity including one or more dispersion elements, each of which provides only normal group velocity dispersion, said laser cavity at least including:
- a chirping element for broadening a multiple frequency component pulse in said cavity and spreading said frequency components in said pulse apart over time; and
a spectral bandpass filter for passing a portion of said chirped pulse including only frequency components in a narrow range around a selected center frequency, thereby producing self-amplitude modulation of said pulse.
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Abstract
A modelocked fiber laser is designed to have strong pulse-shaping based on spectral filtering of a highly-chirped pulse in the laser cavity. The laser generates femtosecond pulses without a dispersive delay line or anomalous dispersion in the cavity.
16 Citations
23 Claims
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1. A fiber laser for facilitating generation of femtosecond duration pulses comprises a gain fiber to increase the energy of a pulse in a laser cavity that is free of anomalous dispersion and whose dispersion elements inside said cavity consist only of elements with normal group velocity dispersion, said cavity including one or more dispersion elements, each of which provides only normal group velocity dispersion, said laser cavity at least including:
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a chirping element for broadening a multiple frequency component pulse in said cavity and spreading said frequency components in said pulse apart over time; and a spectral bandpass filter for passing a portion of said chirped pulse including only frequency components in a narrow range around a selected center frequency, thereby producing self-amplitude modulation of said pulse. - View Dependent Claims (2, 3, 4, 7, 8, 18)
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5. A fiber laser for generating femtosecond duration pulses comprises a gain fiber to increase the energy of a pulse in a laser cavity that can only exhibit normal group velocity dispersion, said cavity including one or more dispersion elements, each of which provides only normal group velocity dispersion, said laser cavity at least including:
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a chirping element for broadening a multiple frequency component pulse in said cavity and spreading said frequency components in said pulse apart over time; and a spectral bandpass filter for passing a portion of said chirped pulse including only frequency components in a narrow range around a selected center frequency, thereby producing self-amplitude modulation of said pulse, wherein said laser cavity includes an output and said laser further comprises a pulse dechirping element connected to said output for narrowing said pulse to femtosecond duration. - View Dependent Claims (6)
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9. A method for shaping a pulse in a laser cavity of a fiber laser that employs a gain fiber to increase the energy of a pulse in said laser cavity and is free of anomalous dispersion inside said cavity by having only dispersion elements with normal group velocity dispersion inside said cavity to facilitate generation of femtosecond duration pulses by said laser, said cavity also including one or more dispersion elements, each of which provides only normal group velocity dispersion, said method comprising the steps of:
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chirping a multiple frequency component pulse in said cavity by broadening said pulse and spreading said frequency components in said pulse apart over time; and filtering said chirped pulse with a band pass spectral filter that passes only a portion of said chirped pulse having only frequency components in a narrow range around a selected center frequency;
thereby producing self-amplitude modulation of said pulse. - View Dependent Claims (10, 11, 12, 13, 14, 17)
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15. A method for shaping a pulse in a laser cavity of a fiber laser that employs a gain fiber to increase the energy of a pulse in said laser cavity that can only exhibit normal group velocity dispersion inside said laser cavity to facilitate generation of femtosecond duration pulses by said laser, said cavity also including one or more dispersion elements, each of which provides only normal group velocity dispersion, said method comprising the steps of:
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chirping a multiple frequency component pulse in said cavity by broadening said pulse and spreading said frequency components in said pulse apart over time; and filtering said chirped pulse with a band pass spectral filter that passes only a portion of said chirped pulse having only frequency components in a narrow range around a selected center frequency;
thereby producing self-amplitude modulation of said pulsewherein after said pulse is shaped in said cavity, the shaped pulse is output from said cavity and passed through a dechirping element to narrow the duration of the pulse. - View Dependent Claims (16)
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19. A fiber laser for facilitating generation of femtosecond duration pulses via mode locking, comprising:
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a laser cavity that includes only elements with normal group velocity dispersion inside the laser cavity and is free of anomalous dispersion inside the laser cavity, the laser cavity including a gain fiber that exhibits a normal group velocity dispersion and increases energy of a pulse in the laser cavity, and dispersion elements, each of which provides only normal group velocity dispersion, wherein the laser cavity is structured to effectuate broadening of a multiple frequency component pulse in the laser cavity and spreading frequency components in the multiple frequency component pulse apart over time to produced a chirped pulse, wherein the laser cavity includes a spectral bandpass filter that passes a narrow slice of the chirped pulse containing only frequency components centered about a selected center frequency and exhibits a normal group velocity dispersion, and wherein the laser cavity is structured to achieve self-amplitude modulation of the chirped pulse and to achieve mode locking. - View Dependent Claims (20, 21, 22, 23)
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Specification