In {TAIL ~ a preferred form}, 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 {HEAD ~ an N×N GMZI} with a × non blocking switch 
In { TAIL ~ a preferred form } , 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 { HEAD ~ an N×N GMZI } with a × non blocking switch
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH