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