A traveling-wave photomultiplier

The demodulation of microwave-modulated light has been demonstrated using both photoemissive devices and semi-conductor photodiodes. However these devices are presently not sensitive enough for use in practical wide bandwidth optical systems. Some form of internal current gain is necessary in order to achieve a sensitivity comparable with conventional photomultiplier tubes. Electron multiplication at microwave frequencies has been demonstrated in dynamic crossed-field photomultipliers and in a static crossed-field photomultiplier, each having a rather low impedance coaxial output. In addition TSEM films have been used in conjunction with a traveling-wave output section, but these devices are rather limited in allowable current density.