Study on Photo-Cell with an Optical Fiber Coupling as a Power Supply for Micromachine

Abstract

A pn junction photo-cell with an optical fiber coupling is fabricated as a power supply for Micromachines and its fundamental characteristics are evaluated. The photo-cell consists of two V-grooves spaced out 50μm apart and parallel each other, and a light receiving region between them. The pn junction is formed in a single side of one of two V-grooves and p+ diffusion layer is formed in a single side of the other groove. Since carrier collection efficiency of the photo-cell is more improved than a conventional planar type one, the conversion efficiency is very improved. An opto-electric transformer is fabricated as a combination of V-groove type photo-cell and a bulk transformer for voltage stepping-up. The modulated light with a rectangular waveform is used instead of dc light because of using transformer. The secondary output voltage of 1.5V is obtained for the primary input voltage of 0.3V at the frequency of 100kHz according to the turns ratio of the transformer.