Research On Birefringence And Verdet Constant In Optical Glass Current Sensing Elements

This paper contains two parts which are two subitems of the study of optical current transformers. One of them is the new method to measure the linear birefringence in the bulk glass optical current sensing head, and the other one is the wavelength accumulation effect of the Verdet constant on the broadband OCS system.Linear birefringence is one of the most important parameters of optical (fiber-optic) current sensing heads, which can obviously affect the performance of the optical current sensors. Therefore, it is of great importance to research the measurement method of the linear birefringence inside the optical current sensing head for the research, the development, the manufacture and the property enhancement of the optical current sensors. This paper researches the method to measure the linear birefringence inside the bulk glass current sensing head theoretically and experimentally, and improves the measurement method proposed by the author in the early work. Meanwhile, the theoretical analyses of the improved method and an applied example are given in this paper, which verifies this method correct and feasible. The research result shows that this method can certainly enhance the measurement precision.Verdet constant is one of the prominent parameter showing the property of magneto-optical materials and it has dispersion features. Therefore, there will be wavelength accumulation effect in the systems employing broad-band optical sources. It is not proved how much this effect can affect the broad-band system up till now. Therefore, it is necessary to research into it. This paper calculates the value of the magneto-optic coefficient in the dispersion formula of Verdet constant of ZF-7 glass and gives the theoretical analyze and digital simulate of the wavelength accumulation effect of Verdet constant upon a broadband OCS. The results show that the wavelength accumulation effect is less enough. Consequently, the treatment of using monochromatic model to describe broad-band systems isreasonable and feasible, if the wavelength accumulation effects of the other optical parameters of the sensing head are not considered.The results proposed in this paper might be a reference to the colleagues working in the optical current sensing techniques area.