Speckle reduction based on ultrashort laser pulse

In this paper, a method to reduce spatial coherence of the emission and improve intensity distribution by ultrashort laser pulses has been proposed. The spatial decoherence manifests itself in the formation of a Gaussian far field intensity distribution. For lasers with a high Fresnel number, the loss of full spatial coherence is usually due to the coemission of multiple mutually incoherent transverse modes, which are individually fully spatially coherent. That is to say, it is due to breakdown of the modal emission of these lasers.