POWER RECEIVING DEVICE, POWER FEEDING DEVICE, AND OPTICAL FIBER POWER FEEDING SYSTEM

A powered device includes a photoelectric conversion element, a detector and a signal outputter. The photoelectric conversion element converts feed light into electric power. The detector detects a magnitude of the electric power being transmitted from the photoelectric conversion element to a load. The signal outputter outputs a detection signal of the detector to outside of the powered device. The detection signal is a signal indicating an envelope of a modulated wave that is output by the load.