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