Optical current sensor immune to reflection phase shift based on graded-index magneto-optical glass

We propose a new design of bulk glass optical current sensor immune to reflection phase shift, in which an annular graded-index magneto-optical glass with a small prism is used as a sensing head, and the inner and outer layers of the glass possess gradient refractive indices, while the center layer is uniform. Our theoretical analyses show that under certain conditions the light beam will no longer reach the interface between the magneto-optical glass and air during the propagation in the sensing head. Therefore the reflection phase shift could be avoided essentially, resulting in dramatic enhancement of the sensitivity. The influences of the geometrical parameters on the beam traces and the effective range of the initial angle are specified by numerical simulations. (C) 2009 Optical Society of America