Improvement of near-field beam quality for high-power laser pulses by a two-photon-absorption organic compound

A compound was prepared by introducing a dicyanomethylene group in a benzylidene cyclopentanone dye. The two-photon absorption properties and optical-limiting behavior of the compound in N,N-dimethylformamide (DMF) were investigated. An ultrashort laser source with 130-fs pulse width and 1064-nm wavelength was used. The compound exhibits obvious optical-limiting behavior and two-photon absorption is the predominant mechanism causing the observed behavior. The compound in DMF was applied to improve the near-field beam quality for the pump laser system of an ultra-intense and ultrashort laser facility. The results show that the near field of the pump laser beam becomes more homogeneous after passing through the compound solution and high beam quality is achieved.