FIG. 1.

Schematic view of (a) the dual frequency acoustic or laser structure and its equivalent circuits for (b) high frequency reception; (c) low frequency transmission. Parameters L and Z denote the length and impedance of the particular material or port with subscripts M, HM, HA, AF, LA, and B indicating materials of the Medium, High frequency Matching, High frequency Active element, Acoustic Filter, Low frequency Active element, and Backing, respectively. Subscripts H1, H2, H3, L1, L2, and L3 denote the input/output impedance at the ports shown in the figures with H/L denoting the High/Low frequency waves, respectively.