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