Brewster-Angle Pockels Cell Design

A Pockels cell having all surfaces at Brewster's angle is described. A simple analysis is presented to show that the extinction ratio of a quarter-wave mode Q-switch using this design is limited to 180:1 by the presence of Brewster faces on the crystal when the cell is closed by one window and one resonator mirror, whereas the ratio is limited to 28:1 if two Brewster windows are used to close the cell. The measured extinction ratio of an experimental cell based on the design requiring a single window is 150:1. Operation of a ruby laser using the Q-switch is described, and the possibility of using the cell to obtain high contrast ratio, low loss selection of pulses from mode-locked pulse trains is discussed.