Fiber optic power-feed system

An effort was made to realize an optical power-feed system by which power can be supplied to the sensors and interfacing circuits. Laser light was transmitted to solar cells in which the optical energy is converted into electrical energy. A laser diode (wavelength 813 nm, maximum optical power 800 mW) was used as a light source. A laser diode with graded-index fiber coupling (230 mu m in core diameter) was connected to the solar cells. Several solar cells connected in series are assembled around the fiber end. The active area of each solar cell was 0.5*0.27 cm. The open-circuit voltage and the short-circuit current were measured. The result obtained was that open-circuit voltage was linearly related to the number of solar cells, while short-circuit current was decreased in inverse proportion to the number of solar cells. In an eight-solar-cell configuration, the open-circuit current was about 7 mA with an optical power of the laser diode of 650 mW.< >