{HEAD ~ a laser} optically coupled to {TAIL ~ said first light input} via a first optical fiber and optically coupled to said second light input via a second optical fiber 
optically coupled to
{ HEAD ~ a laser } optically coupled to { TAIL ~ said first light input } via a first optical fiber and optically coupled to said second light input via a second optical fiber
HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL 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