POWER FEED DEVICE OF AN OPTICAL POWER FEED SYSTEM AND OPTICAL POWER FEED SYSTEM

An optical fiber power feed system 1A1 comprises a power feed device 110, and a power receiving device 310 that converts power feed light from the power feed device to power. The power receiving device comprises: a photoelectric conversion element 311 that converts power feed light 112 from the power feed device to power; a feedback semiconductor laser 311F that uses a portion Q2 of a power Q converted by the photoelectric conversion element to do laser oscillation and outputs a power feed light 112F to the power feed side; and a control device 312 that monitors a power feed amount Q1 to the power load and controls the conversion amount by the feedback semiconductor laser according to the power feed amount. The power feed device comprises: a semiconductor laser 111 that does laser oscillation using power and outputs the power feed light 112 to the power receiving device; and a feedback photoelectric conversion element 111F that converts power feed light from the power receiving device to power and outputs that as drive power of the semiconductor laser. With an other system 1A2, a portion of the power feed light is circulated directly as the feedback power feed light 112F.