Spatio-temporal modification of femtosecond focal spot under tight focusing condition.

The focusing property of a focal spot of a femtosecond laser pulse is presented under tight focusing conditions (below f-number of 1). The spatial and temporal intensity distributions of a focused electric field are calculated by vector diffraction integrals and coherent superposition method. The validity of the calculation method is examined by comparing the intensity distribution obtained under a high f-number condition to that obtained with the fast Fourier transform method that assumes the scalar paraxial approximation.

High-average-power diode-array-pumped frequency-doubled YAG laser.

We report on the laser performance and power scaling properties of a diode-laser side-pumped Nd:YAG laser operating at high average power. The Nd:YAG laser is pumped by 35 20-W cw bars and produces 106 W of average power at 532 nm when it is intracavity doubled with KTiOPO(4) and Q switched at 27 kHz, leading to a 5.4% optical-to-electrical efficiency.