Research on the Optical Current-Transformer Using Fe-Mn Diluted Magnetic Semiconductor Films as a Faraday Rotator

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The optical current transformer (OCT) was scarcely used in applications so far. Recently some new researches on the OCT have been begun for its practical application and improvements of performance. The purpose of those researches is to develop the OCTs that can be incorporated into electric power devices like the circuit-breakers, taking full advantage of the OCT that is light weight, small size and good isolation.In this research, the possibility of applying diluted magnetic semiconductor (DMS) films prepared by using Molecular Beam Epitaxy to the optical current transformer is studied. And magneto-optical properties of the DMS films are investigated to accomplish the purpose of our research plan.(Year : 1998)It has been confirmed that the optical current transformer can be applied to the current measurements in the flat-shape bus-bars used for the three-phase low power distribution equipment of 3000 〜 6000 V. The OCTs for such applications should be further improved in terms of opti … More cal loss.The investigation about the M-0 properties of DMS films has shown the following :(1) The specific rotation of the CdFeTe films is one or two orders of magnitude larger than that in the CdMnTe films. (2) The specific rotation of the CdFeTe films exhibits a positive sigh in the wavelength region of 550-750nm, although it in the CdMnTe films is almost negative in the same region. (3) Since Fe ions do not widen the optical band gap as Mn ions do, transparency is not improved in the visible wavelength region.(Year : 1999)Magneto-optical properties in the visible wavelength region have been studied on four-element semimagnetic semiconductor CdMnCoTe films deposited on quartz glass substrate by using MBE equipment. The value of Faraday rotation of 0.3 deg/cmG in the CdィイD20.647ィエD2MnィイD20.34ィエD2CoィイD20.013ィエD2Te film has been observed at 570 nm. This is approximately two times larger than that of the CdィイD20.61ィエD2MnィイD20.39ィエD2Te film on quartz glass. It has been confirmed by using vibrating sample magnetometer (VSM) that the CdィイD20.647ィエD2MnィイD20.34ィエD2CoィイD20.013ィエD2Te film prepared is paramagnetic. Less