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 language | English |
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Article number | 8814 |
Journal | Nature Communications |
Volume | 6 |
DOIs | |
State | Published - Oct 30 2015 |
Externally published | Yes |
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.