An optical waveguide photocathode for converting optical signals to electrical signals has an optical waveguide, a semiconductor covering the end of the optical waveguide, a first transparent electrode disposed between the end of the waveguide and the semiconductor, and a second electrode disposed adjacent to and spaced from the semiconductor. An electric potential is applied between the first electrode and the second electrode. The waveguide, first conductor, and semiconductor are relatively pointed at the end to produce high electric field strength at the semiconductor thereby enabling semiconductors with high work functions to be used. The relatively small area of the semiconductor illuminated by the waveguide reduces the dark current, making the device more sensitive to low level signals. The device may be used in a streak tube or a photomultiplier.