Method and device for the generation of ultrashort optical pulses
AssigneeCSELT - Centro Studi e Laboratori Telecommunicazioni S.p.A.
InventorsRenato Caponi, Riccardo Calvani
Life of this patent
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Abstract
Transform-limited ultrashort optical pulses are obtained by sending into a dispersion-shifted optical fibre pulses of such duration and intensity as to produce self-phase modulation. The pulses are also made to travel through a conventional fibre with suitable dispersion and are subjected to optical filtering, so as to compensate, for a particular peak power, the phase effect due to the chirp. Pulse peak power is selected so as to coincide with the vertex of the parabola plotting the square of the duration of the outgoing pulse versus the peak power of the incoming signal.
Claims7
A method of generating ultrashort optical pulses, comprising the steps of:
- launching optical pulses, subject to chirp and having a wavelength lying within a first band, into a compensating optical fiber whose minimum dispersion lies in a second band other than the first band and whose length and dispersion characteristics are such as to compensate for a phase distortion induced by the chirp;
- propagating said pulses also in a dispersion-shifted optical fiber having a dispersion minimum in said first band and arranged in series with compensating fiber;
- and
- sending said pulses into the series of the compensating and dispersion-shifted optical fibers with such a peak power as to give rise to self-phase modulation in the dispersion-shifted fiber so that the compensating fiber compensates chirp due to self-phase modulation, and such as to coincide with a vertex of a parabola representing a square of a full width at half maximum of the pulses expressed as a function of peak power.
A device for the generation of ultrashort optical pulses, comprising:
- a source of pulses whose wavelength lies within a first band;
- and a compensating single mode optical fiber which is traversed by pulses emitted by the source, has minimum dispersion in a second band other than the first band and such dispersion characteristics as to compensate for the phase distortion due to a chirp of the pulses;
- a span of dispersion-shifted optical fiber which has a dispersion minimum in said first band and is arranged in series with said compensating fiber along a path of the pulses;
- and
- means for adjusting power of the pulses emitted by the source, in such a way that they are sent into the series of the two fibers with such a peak power as to give rise to self-phase modulation in the dispersion-shifted fiber and such as to coincide with a vertex of the parabola representing a square of a full width at half maximum of the pulses expressed as a function of peak power.
Dependencies are inferred from the claim text.