Architecture of crosstalk-reduced digital optical 2*2 switch (CRDOS)

Coherent crosstalk of optical space switch matrices is a key problem of optical transparent networks. An analysis of the crosstalk sources of electrooptical digital switches (DOS) is given and a new crosstalk compensating technique based on the integration of a general mode converter as correcting device into a 3*2 DOS is proposed and theoretically investigated. It can be shown, that a -20 dB crosstalk 2*2 DOS device can be enhanced to -40 dB. This architecture leads to an increase of the device length by only a few percent. It opens up the possibility to realize short optical switches for larger matrices.