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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84 Scopus citations

Abstract

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
Article number8814
JournalNature Communications
Volume6
DOIs
StatePublished - Oct 30 2015
Externally publishedYes

Funding

S.S., J.P., S.C. and H.C. were supported by Samsung Research Funding Center of Samsung Electronics under Project Number SRFC-MA1402-02, National Research Foundation of Korea (NRF) through the government of Korea (MSIP) (Grant Nos NRF-2011-0013255, NRF-2009-0083512 and WCI 2011-001), Global Frontier Program (2014M3A6B3063709), the Yonsei University Yonsei-SNU Collaborative Research Fund of 2014, and the Yonsei University Future-leading Research Initiative of 2014. H.J. and J.-H.A. were supported by NRF of Korea through the government of Korea (MSIP) (Grant No. NRF-2009-0083540). N.K., M.B., J.M. and S.O. were supported by ONR (N000141210456), NSF (DMR-1308142) and Gordon and Betty Moore Foundation’s EPiQS Initiative (GBMF4418). J.H.S. and M.-H.J. were supported by Institute for Basic Science, Korea under the contract number of IBS-R014-G1.

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