Optical switching system for digitised TV signals - uses assembly of birefringent cells which polarise signal beams for deviation to photocells by separator as function of polarisation

摘要

The system has a multiplexer which routes a number of signals from transmitting units to a switching unit. The switching unit comprises an electro-optic converter comprising a laser diode (7) whose output is directed to a deflection assembly. This comprises a linear polariser and a cascaded assembly of cells (13) which become birefringent when an electric field is applied from a logic circuit (5) driven from the multiplexer. This is followed by a separator (14) which is able to deviate the beam as a function of the polarisation of the beam from the birefringent element. The beams (d1,d2) from the separator are directed to photocells each connected to a respective receiver.