Ultra-high modulation depth exceeding 2,400% in optically controlled topological surface plasmons

Sangwan Sim, Houk Jang, Nikesh Koirala, Matthew Brahlek, Jisoo Moon, Ji Ho Sung, Jun Park, Soonyoung Cha, Seongshik Oh, Moon Ho Jo, Jong Hyun Ahn, Hyunyong Choi

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44 Scopus citations


Modulating light via coherent charge oscillations in solids is the subject of intense research topics in opto-plasmonics. Although a variety of methods are proposed to increase such modulation efficiency, one central challenge is to achieve a high modulation depth (defined by a ratio of extinction with/without light) under small photon-flux injection, which becomes a fundamental trade-off issue both in metals and semiconductors. Here, by fabricating simple micro-ribbon arrays of topological insulator Bi 2 Se 3, we report an unprecedentedly large modulation depth of 2,400% at 1.5THz with very low optical fluence of 45μJcm-'2. This was possible, first because the extinction spectrum is nearly zero due to the Fano-like plasmon-phonon-destructive interference, thereby contributing an extremely small denominator to the extinction ratio. Second, the numerator of the extinction ratio is markedly increased due to the photoinduced formation of massive two-dimensional electron gas below the topological surface states, which is another contributor to the ultra-high modulation depth.

Original languageEnglish (US)
Article number8814
JournalNature communications
StatePublished - Oct 30 2015

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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