{TAIL ~ a substrate} on which {HEAD ~ a surface acoustic wave propagation region} for guiding a surface acoustic wave and an optical waveguide for guiding an optical wave are provided; and 
on
{ TAIL ~ a substrate } on which { HEAD ~ a surface acoustic wave propagation region } for guiding a surface acoustic wave and an optical waveguide for guiding an optical wave are provided ; and
TAIL TAIL TAIL TAIL TAIL TAIL REL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH