The mode conversion means is provided in the substrate, in the light emitting layer, or at the interface between the substrate and {TAIL ~ the light} emitting {HEAD ~ layer} 
The mode conversion means is provided in the substrate , in the light emitting layer , or at the interface between the substrate and { TAIL ~ the light } emitting { HEAD ~ layer }
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 OTH HEAD HEAD HEAD HEAD HEAD