The second optical waveguide converts the single mode optical signal output from the first optical waveguide to a multi mode optical signal and allows {HEAD ~ the optical power} of the single mode optical signal to be coupled to {TAIL ~ each mode} of the multi mode optical signal 
The second optical waveguide converts the single mode optical signal output from the first optical waveguide to a multi mode optical signal and allows { HEAD ~ the optical power } of the single mode optical signal to be coupled to { TAIL ~ each mode } of the multi mode optical signal
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH