Condition for unity absorption in an ultrathin and highly lossy film in a Gires-Tournois interferometer configuration

Junghyun Park, Soo Jin Kim, Mark L. Brongersma

Research output: Contribution to journalArticle

19 Citations (Scopus)


We present a condition for unity absorption for a Gires-Tournois interferometer configuration constructed from an ultrathin and highly lossy film on top of metallic mirror. From the impedance matching condition in the transmission line theory, we identify a solution space for the required complex refractive index of the lossy film in various film thickness and dielectric constants of the metallic mirror. It is shown that strong absorption requires the imaginary part of the refractive index of the ultrathin lossy film be larger than 0.64, and the physical origin of this condition is elucidated. The proposed method is useful in identifying candidate semiconductor materials that can be used as the lossy film in a unity-absorption Gires-Tournois interferometer configuration and designing the thickness of this film to maximize absorption.

Original languageEnglish
Pages (from-to)1960-1963
Number of pages4
JournalOptics Letters
Issue number9
Publication statusPublished - 2015 Jan 1
Externally publishedYes


ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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