Multiple-frequency perfect absorption by hybrid membrane resonators
Suet To Tang, Joshua Lau, Ka Yan Au Yeung, Zhiyu Yang
Abstract
Besides generating their own perfect absorption bands, the primary hybrid resonances of a hybrid membrane resonator (HMR) consisting of a decorated membrane resonator (DMR) backed by a cavity can also provide strong assistance for weak resonances to create secondary hybrid resonances and multiple-frequency perfect absorption by forming a low impedance region between the primary hybrid resonances. The weak resonances can be introduced by placing another DMR in front of a HMR or by using a DMR with an off-centered platelet in an HMR. In one such sample, five perfect absorption bands within the range of 200–1000 Hz are experimentally observed with minimum reflection values ranging from 1.2% to 7%.