| 摘要 |
A family of optical switches employ dielectric film polarizing beam splitters and switchable electro-optic retarder to produce 2x2 optical switches which exhibit low crosstalk characteristics while switching unpolarized or linearly polarized collimated light. The switches all contain four port modules through which light enters and leaves the switch. The port modules utilize polarizing beam splitters to separate incoming light into two orthogonal linearly polarized components. The component beams are made parallel after which each passes through an electro-optic retarder. The retarders are electrically driven so as to selectively change the polarization of either one of the two component beams, thus making the polarizations the same. Other polarizing beam splitters are disposed to direct the component beams along one of two pairs of paths as determined by their common polarization. The pairs of paths associated with each of the port modules are positioned and aligned in two sets of pairs, and the electro-optic retarders of the four port modules are jointly controlled electrically so that light entering the switches through any one port can be switched to selectively leave through either of two of the remaining ports. The two ports not thus connected as the foregoing pair are themselves connected so that light may pass between them.
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