Improved optical filter responses in cascaded InGaAsP/InPmicrodisk resonators

Abstract
Cascaded InGaAsP/InP microdisk resonators as optical filters are fabricated by deep dry-etching. Compared with single microdisk resonators, these higher-order filters show steeper rolloffs and flatter passbands. The bandwidth ratios of 15 to 3 dB for the single, three and five cascaded microdisk resonator filters are ~2.4, 1.4 and 1.2.