Plate modes in langasite

The characteristics of plate modes propagating under Pt grating in rotated Y-cuts of LGS were simulated as functions of the cut angle and plate thickness. Quasi-symmetric and quasi-anti-symmetric modes, which can be excited in rotated YX-cuts, and SH-polarized modes propagating in rotated Y-cuts with propagation direction normal to the X-axis demonstrated high electromechanical coupling up to 2.7%, in some orientations combined with zero TCF. The variation of the mode characteristics with plate thickness was investigated in YX and YZ cuts as the typical examples of the two cut families. The effect of metal film at the plate bottom on electromechanical coupling of different modes was investigated.