Improved Germanium photoswitch for cavity dumping of a free-electron laser

We demonstrate an optical switch based on gold implanted germanium (Ge:Au) suitable for cavity dumping of a free-electron laser (FEL). We achieve a switching contrast of more than 50 % in a broad range of FEL wavelengths from 6 to 90 µm. A linear relationship between the switching fluence and the frequency of the FEL optical field supported by our simulation highlights the role of a photoinduced f...