In this instance, {HEAD ~ a buffer layer} for preventing propagation loss of the optical waves in the excitation electrode may be formed between the substrate and {TAIL ~ the excitation electrode} 
In this instance , { HEAD ~ a buffer layer } for preventing propagation loss of the optical waves in the excitation electrode may be formed between the substrate and { TAIL ~ the excitation electrode }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL