Patent ID: 8481937

Claim:
A photocathode apparatus, comprising: a transparent body adapted to receive incident light; and a single metal cover layer formed on a first surface of said transparent body, wherein said metal cover layer includes an incident/reflective surface which receives said incident light through said first surface of said transparent body to excite surface plasmon resonance light in said incident/reflective surface of said metal cover layer, thus emitting photoelectrons from a photoelectric surface of said metal cover layer opposite to said incident/reflective surface thereof by a photoelectric effect of one of surface plasmon resonance photons and a second harmonic generation wave of said surface plasmon resonance photons, wherein said photocathode apparatus further comprises a layer including one of an alkali metal and an alkali metal compound formed directly on the photoelectric surface of said metal cover layer, wherein said layer including one of an alkali metal and an alkali metal compound decreases a work function of said metal cover layer.