In sum, the total time that it takes {HEAD ~ the optical signal} to travel from {TAIL ~ the input element} to the output element depends on its wavelength 
to travel from
In sum , the total time that it takes { HEAD ~ the optical signal } to travel from { TAIL ~ the input element } to the output element depends on its wavelength
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH