Nonlinear chirped pulse fiber amplifier with pulse compression
First Claim
1. A method for generating high power ultrashort-pulses using a chirped pulse fiber amplifier, comprising the steps of:
- chirping an input pulse to be amplified by passing said pulse through a pulse stretcher, thereby creating a chirped pulse that is broadened in time;
modifying said chirped pulse by increasing the power of said pulse with a fiber amplifier to induce an amount of nonlinear phase shift in said pulse which substantiality changes a shape of a power spectrum of said pulse and is sufficient to broaden the power spectrum of said pulse beyond a gain bandwidth of the fiber amplifier; and
dechirping said pulse by passing said pulse through a pulse compressor to generate a narrowed output pulse having a duration below a gain narrowing limit of said fiber amplifier, wherein said pulse stretcher and said pulse compressor have mismatched dispersion characteristics that combine to induce an amount of third order dispersion in said pulse that is sufficient to compensate for the amount of nonlinear phase shift induced in said pulse by said fiber amplifier.
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Abstract
A chirped-pulse fiber amplification method and system operates with large nonlinear phase shifts (as large as ˜20π or more). In this regime, the pulse spectrum is modified by strong self-phase modulation and gain shaping. With large-enough nonlinear phase shift, substantial spectral broadening occurs. The amplified spectrum can therefore be much broader than the spectrum that is obtained with small nonlinear phase shifts. The broader spectrum enables the formation of a shorter pulse, and the bandwidth generated in nonlinear chirped-pulse amplification can in fact be exploited to generate shorter pulses. Ultimately, this allows the generation of pulses shorter than the gain-narrowing limit of a fiber amplifier.
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Citations
11 Claims
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1. A method for generating high power ultrashort-pulses using a chirped pulse fiber amplifier, comprising the steps of:
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chirping an input pulse to be amplified by passing said pulse through a pulse stretcher, thereby creating a chirped pulse that is broadened in time; modifying said chirped pulse by increasing the power of said pulse with a fiber amplifier to induce an amount of nonlinear phase shift in said pulse which substantiality changes a shape of a power spectrum of said pulse and is sufficient to broaden the power spectrum of said pulse beyond a gain bandwidth of the fiber amplifier; and dechirping said pulse by passing said pulse through a pulse compressor to generate a narrowed output pulse having a duration below a gain narrowing limit of said fiber amplifier, wherein said pulse stretcher and said pulse compressor have mismatched dispersion characteristics that combine to induce an amount of third order dispersion in said pulse that is sufficient to compensate for the amount of nonlinear phase shift induced in said pulse by said fiber amplifier. - View Dependent Claims (2, 3, 4, 5, 7, 8)
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6. A chirped pulse fiber amplifier system for generating high power ultrashort-pulses comprising:
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a pulse stretcher for chirping an input pulse to be compressed, thereby creating a chirped pulse that is broadened in time; a fiber amplifier for modifying said chirped pulse by increasing the power of said pulse, said amplifier having a gain that is selected to induce an amount of nonlinear phase shift in said pulse which substantiality changes a shape of a power spectrum of said pulse and is sufficient to broaden the power spectrum of said pulse beyond a gain bandwidth of the fiber amplifier; and a compressor for dechirping said pulse to generate a narrowed output pulse having a duration below a gain narrowing limit of said fiber amplifier;
wherein said pulse stretcher and said pulse compressor have mismatched dispersion characteristics that combine to induce an amount of third order dispersion in said pulse that is sufficient to compensate for the amount of nonlinear phase shift induced in said pulse by said fiber amplifier. - View Dependent Claims (9, 10, 11)
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Specification