STM (scanning tunneling microscope) light emission from an evaporated Au film irradiated by pico second laser pulses has been investigated for various bias voltages of the STM. The observed emission consists of two components. The first component that has the same duration as the incident laser pulse is excited by laser induced tunneling electrons. The second component that has a longer duration than that of the laser pulse is emitted from surface polariton plasmons excited nonlinearly by the laser pulse.