Verdet constant limited temperature response of a fiber-optic current sensor

A novel all-fiber, magnetooptic current transformer is reported. Changes of the optical system response to current with temperature have been measured to be linear with a slope of 6.9/spl times/10/sup -5///spl deg/C with an error bar of less than 0.2% over the temperature range of -40 to +80/spl deg/C. This temperature dependence can be entirely attributed to the change in the Verdet constant of the glass. This is, to our knowledge, the first report of a birefringence free fiber-optic current sensor with Verdet constant limited performance. The sensor´s response to current is linear to within 0.3% from less than one amp up to 110 amps, the limit of our measurement capability.