With the OEC, {TAIL ~ the optical signal} coupled thereon is converted into {HEAD ~ an electrical signal} 
With the OEC , { TAIL ~ the optical signal } coupled thereon is converted into { HEAD ~ an electrical signal }
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD