PROBLEM TO BE SOLVED: To actualize the size reduction of the devices, the simplification of designing, low loss, high efficiency, wide bandwidth, controllability of dispersion characteristics, etc., as compared with a convertional dispersion delay line used for an extremely-short pulse system. ;SOLUTION: This extremely-short pulse amplifying device uses a chirp quasi- phase synchronous (QPM) grating 12 as a dispersion delay line for expanding extremely-short pulses. The QPM grating 12 which varies in cycle in the propagation direction of a beam generates a secondary higher harmonic at the same time. In general, the output of this secondary higher harmonic is modulated together with the amplitude and phase. The QPM grating 12 also expands the secondary higher harmonic of an input pulse of basic wavelength. In general, the periodic QPM grating 12 can efficiently generate secondary higher harmonic pulses which are optionally shaped.;COPYRIGHT: (C)1998,JPO
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