In this way {HEAD ~ the total optical path length} of the signal in the time delay unit depends on {TAIL ~ its optical wavelength} 
depends on
In this way { HEAD ~ the total optical path length } of the signal in the time delay unit depends on { TAIL ~ its optical wavelength }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL