Photodiodes as current source in high-frequency low temperature applications

Prospects of exploiting photodiodes as a high frequency current source for low temperature applications is presented. The source will be implemented in the AC Josephson Standard of the Q-Wave project within the European Metrology Research Programme. Method for optically biasing the diodes is described and some initial results of photocurrent measurements at 4K indicates that high frequency ~28 GHz photodiodes could be exploited as current source for Josephson Arbitrary Waveform Standard.