Optical power supply for fiber-optic hybrid sensors

Abstract Systems for optical power supply are of central importance for the concept of fiber-optic hybrid sensors. We present our systems for optical power supply which are capable of giving up to 150 mW of electrical power to the sensor head. Such a system for optical power supply consists of a combination of optical and electronic modules, namely a suitable optical power source, an optical fiber as power link and an optical energy converter with voltage control unit. This concept of a fiber-optic power supply in combination with a fiber-optic hybrid sensor covers many of the advantages given by a pure optical sensor. The galvanic isolation between the measuring circuit and the electronic evaluation unit is notable and implies use at higher voltages with high immunity to interference (EMI) of the data transmission line. A key element for our fiber-optic power supply is a specially developed photo-element array (PEA) for optical–electrical power conversion. Conversion efficiencies of 10–15% ith silicon material and up to 30% with GaAs material have been achieved. The available voltage with our single photoelement array (SPEA) can be up to 8 V. With a multiple photoelement array (MPEA) the voltage is switchable between 8 and 32 V. An application example for a complete fiber-optic hybrid sensor is given. With the fast rate of development of electronic and optoelectronic components, further improvements and a broad range of practical applications can be expected. An outlook to possible future improvements is given.