| 摘要 |
PCT No. PCT/GB95/02327 Sec. 371 Date Jul. 24, 1997 Sec. 102(e) Date Jul. 24, 1997 PCT Filed Sep. 29, 1995 PCT Pub. No. WO96/10776 PCT Pub. Date Apr. 11, 1996A polarisation independent optical switch is constituted by a light input (6), a diffractive and re-configurable liquid crystal device (8), a collimating lens (7) for distributing the input light over the liquid crystal device (8), a transform lens (9) receiving light from the liquid crystal device (8) and light output (6), wherein no polarisers are present between the light input and output. The diffractive and re-configurable liquid crystal device (8) may be formed as a liquid crystal spatial light modulator configured as a binary phase computer generated hologram with the holograms required to form broadcast, individual or multicast switching being re-generated using an iterative algorithm and then being recalled on demand. In one embodiment the switch has a folded configuration and includes a reflector (10) so that the light input and output are both on the same side of the liquid crystal device (8).
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