In a preferred form, the present invention provides {HEAD ~ a balanced non blocking switch} by using {TAIL ~ 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 
by using
In a preferred form , the present invention provides { HEAD ~ a balanced non blocking switch } by using { TAIL ~ 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
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH