{HEAD ~ the photonic crystal} having the at least one ferromagnetic control rod which controls {TAIL ~ the magnetic field} in the photonic crystal wherein the at least one ferromagnetic control rod is in turn controlled by a controllable external current 
{ HEAD ~ the photonic crystal } having the at least one ferromagnetic control rod which controls { TAIL ~ the magnetic field } in the photonic crystal wherein the at least one ferromagnetic control rod is in turn controlled by a controllable external current
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH 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 OTH