<title>Fiber optic current transformer with low cost standard connectors employing a fiber depolarizer</title>

Abstract

For the desired improvement of electromagnetic compatibility using optical current transformers a separation of optical sensor head and electronic components by an optical link is required. Intensity modulated optical output signals of a polarimetric fiber optic current transformer can easily be transmitted by standard multimode fibers. A realization of the supply of a sensor fiber with linearly polarized light employing low cost standard monomode fiber is presented here. It is based on the transportation of depolarized optical waves and recovery of lineraly polarized light by a linear polarizer. First three methods of depolarizing optical waves emerging a semiconductor laser source using birefringent materials are theoretically described. They make use of a crystal wedge depolarizer, a crystal Lyot-depolarizer and a fiber Lyot- depolarizer. All methods are reflected on simplicity in handling and possiblity of low cost realization. A Lyot depolarizer employing a high birefringent fiber is chosen and tested. A single ended device of a polarimetric fiber optic current transformer with twisted sensor fiber is provided with such an optical link which transfer characteristics are not influenced by the birefringence properties of standard single mode fibers.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.