Optical space switch and network with such optical space switches

摘要

An optical space switch includes a polarization controller (2), a beam splitter (1), a first reflection block (5) and a second reflection block (8). The polarization controller has a first mode and a second mode. The polarization controller maintains the polarization of input light in the first mode and changes it by 90° in the second mode. The first reflection block includes a quarter wave plate (3) and a light path changing element (4). The input light from the polarization beam splitter is reflected by the first reflection block. During this time, the input light passes through the quarter wave plate twice. Thus, the polarization of the input light is changed by 90°. Further, the light path of the input light is shifted by a predetermined distance by the light path changing element. The second reflection block has a quarter wave plate (6) and a mirror (7). The second reflection block receives the input light from the polarization beam splitter, and returns it thereto. During this time, since the input light passes through the quarter wave plate of the second block twice, the polarization thereof is changed by 90°. The input light is emitted from the polarization beam splitter via a first output path or a second output path.