| 摘要 |
There is provided a device for use with fiber-optic cables for polarization insensitive amplitude modulation of light comprising a planar electro-optic layer with a reflective conductive mirror electrode on one side and a pair of transparent conductive electrodes on the other. The transparent conductive electrodes have a small separation along a straight line. A GRIN lens has one end in optical contact with the transparent conductive electrodes with its axis located over the line separating the electrodes. An input optical fiber and an output optical fiber are placed in optical contact with the other end of the lens at points which are symmetrically displaced from the axis of the lens. Light coming from input fiber is collimated by the GRIN lens and directed to the transparent electrodes, through the electro-optic layer and to the mirror from which it is reflected and refocused by the GRIN lens onto the output fiber. Applying a voltage between any of the transparent electrodes and the reflecting electrode changes the optical path length for half the beam so that when it is refocused on the output fiber, the two halves interfere constructively of destructively, depending on the change in path length. In one version, the electro-optic layer is a PLZT ceramic plate, while in others, it is a thick or thin film. In still other versions, two or more electro-optic layers are used in series in order to reduce the voltage required for the same optical path length change. A means to eliminate residual sensitivity to polarization sensitivity is described.
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