PARTIALLY COHERENT-LIGHT GENERATED BY USING SINGLE AND MULTIMODE OPTICAL FIBERS IN A HIGH-POWER ND-GLASS LASER SYSTEM

A simple and flexible method is presented for generating a partially c oherent light which obtains the highly smooth focused beam pattern. Th e beam divergence of 32 times diffraction limited light having a spect ral width of 1.6 nm has been easily and reproducibly achieved by injec ting a laser pulse from an actively mode-locked Nd:YLF oscillator to a single mode optical fiber, coupled to a multimode optical fiber. Temp oral evolution of the beam smoothing due to the induced incoherency wa s examined with temporally resolved measurements of the beam pattern. The partially coherent light was focused through a random phase plate after the amplification. Small-scale intensity perturbation in a focus ed beam pattern was greatly reduced.