Abstract:

In this work, a pronounced ultrashort pulse contrast enhancement was realized via the utilization of the nonlinear Transient Grating technique with a fiber-chirped pulse amplifier system in the 1μm regime. A YVO4 crystal with significantly enhanced nonlinearity relative to glasses yielded a distinct advantage in pulse cleaning by inducing Transient Grating with intensities that are nearly order of magnitude lower compared to, e.g., fused silica. In addition, the clean beam was inherently separated from the generating beams, eliminating the necessity for supplementary filtration, potentially compromising the final contrast. Up to 40 dB contrast enhancement was observed with ∼1μJ of energy. The absolute measured peak-to-noise contrast was 80 dB, albeit full verification might be masked by the noise floor limit. Setup modifications for higher pulse energies and corresponding higher efficiencies are underway, with the aim of evaluating their suitability for large laser systems.

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