Abstract: A method for filtering noises in an optical parametric chirped-pulse amplifier by a spatial-chirp-dressed seed beam is provided. The various noises that grow during amplification course, including parametric super-fluorescence, pump distortion-induced noise and surface-reflection-initiated pre-pulses, will not have the spatial and temporal chirp. After dechirping amplified signal with a compressor, a main pulse having its spatial and temporal chirp removed completely is produced, while the noises acquire an additional spatiotemporal coupling, making themselves highly distinguishable from signal in space, and hence supporting noise filtering effectively and expediently in spatial domain that would not be possible otherwise. The method has capabilities of an order of magnitude reduction in noise energy and several orders of magnitude enhancement in temporal contrast.

Abstract: A high-fidelity device for single-shot pulse contrast measurement based on quasi-phase-matching includes a generating unit of sampling pulse, a high-fidelity cross-correlation unit of nonlinear SFG and a high-sensitivity signal detecting unit. An innovatively designed dot-mirror or dot-attenuator and correlating crystal. The dot-mirror or dot-attenuator is adopted to suppress the scattering noise, which is mainly induced by air scattering of the main peak of the correlation beam, to a level below the real pulse background. While the crystal is introduced into the device as a nonlinear correlation crystal to move two kinds of artifacts introduced by a correlation process respectively out of the temporal window and behind the main pulse, so that effects of the artifacts on the contrast measurement in a pulse leading edge are removed, without obviously affecting other parameters. The device is also fit for measuring contrasts of high-power lasers of various wavelengths.

Abstract: A high-fidelity device for single-shot pulse contrast measurement based on quasi-phase-matching includes a generating unit of sampling pulse, a high-fidelity cross-correlation unit of nonlinear SFG and a high-sensitivity signal detecting unit. An innovatively designed dot-mirror or dot-attenuator and correlating crystal. The dot-mirror or dot-attenuator is adopted to suppress the scattering noise, which is mainly induced by air scattering of the main peak of the correlation beam, to a level below the real pulse background. While the crystal is introduced into the device as a nonlinear correlation crystal to move two kinds of artifacts introduced by a correlation process respectively out of the temporal window and behind the main pulse, so that effects of the artifacts on measurement results are removed and the single-shot measurement of the contrast in a pulse leading edge is accomplished, without obviously affecting other parameters.