Abstract

The proposed electrooptic fiber interferometer has two branches. Only one branch is made of electrooptic material, such as lithium niobate. When the device is immersed in the electromagnetic field, the velocity of light in only the electrooptic arm is affected. This produces a relative phase difference between the light propagating in the two arms. As a result, the intensity of the recombined output light is a function of the phase difference and strength of the ambient electric field. The interferometer has many advantages: it can be immersed in an electric field directly to measure it, obviating the use of metal electrodes; there is no limitation on the length1; and it can be arranged in various configurations, e.g., linear, spiral, coiled-cylindrical, etc. Other versions of the interferometer are possible. In one version the interferometer contains an optical fiber in one branch and an electrooptic waveguide in the other. The electrooptic waveguide can be titanium in diffused waveguide in lithium niobate. In another version the interferometer has optical fiber for one branch and electrooptic layer waveguide for the other, the optical fiber having been properly shaped, cut, polished, and used to couple light to the electrooptic layer waveguide. The proposed device can be used for high voltage measurement, electromagnetic field detection, modulation, temperature sensing, optical signal processing, and so on.

© 1985 Optical Society of America