Generation of Ultrawideband Electromagnetic Radiation by a Vacuum Photodiode with Anode with a Sapphire Input Window

Generation of ultrawideband electromagnetic radiation by a vacuum photodiode with a plane cesium antimonide photocathode is studied. Thin aluminum plates deposited on a sapphire input window serve as the anode of the photodiode. Electron emission from the photocathode is initiated by the second-harmonic radiation (λ = 385 nm) of a titanium–sapphire laser system with a pulse duration of about 200 fs. Variations in the electric component of the electromagnetic radiation due to changes of the voltage across the interelectrode gap from 13 to 140 kV are measured.