In {TAIL ~ a preferred form}, {HEAD ~ the present invention} provides a balanced non blocking switch by using symmetrical configurations of optically coupled GMZIs, and also provides a cascaded non blocking switch by cascading an N×N GMZI with a × non blocking switch 
In { TAIL ~ a preferred form } , { HEAD ~ the present invention } provides a balanced non blocking switch by using symmetrical configurations of optically coupled GMZIs , and also provides a cascaded non blocking switch by cascading an N×N GMZI with a × non blocking switch
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