Phase shift of stepwise reflectivity profile mirrors.

The effects of phase shifts in laser beams transmitted by output couplers with a stepwise reflectivity profile have been experimentally investigated with a XeCl laser. It is shown that the phase distortions of the cavity output coupler affect significantly the propagation properties of the output laser beam but do not affect the output beam energy and pulse width.

Output coupler design of unstable cavities for excimer lasers.

We tested the performance of a XeCl laser with unstable resonators using as an output coupler a phase unifying (PU) mirror, a super-Gaussian mirror, and a hard-edge mirror. The quantitative impact of the output coupler design on the energy extraction efficiency, near-field profile, far-field energy distribution, and spatial coherence time evolution has been investigated. Laser beams of larger brightness have been obtained with the PU unstable cavity.