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