• Advanced Photonics
  • Vol. 1, Issue 2, 026001 (2019)
Bo Qiang1、2, Alexander M. Dubrovkin1, Harish N. S. Krishnamoorthy1, Qian Wang3, Cesare Soci1, Ying Zhang4, Jinghua Teng3, and Qi Jie Wang1、2、*
Author Affiliations
  • 1Nanyang Technological University, Centre for Disruptive Photonic Technologies, The Photonic Institute, School of Physical and Mathematical Sciences, Singapore
  • 2Nanyang Technological University, Centre for OptoElectronics and Biophotonics, School of Electrical and Electronic Engineering, Singapore
  • 3Agency for Science, Technology and Research, Institute of Materials Research and Engineering, Singapore
  • 4Agency for Science, Technology and Research, Institute of Manufacturing Technology, Singapore
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    Abstract

    Phonon polariton resonances in the mid-infrared spectral range demonstrate properties superior to noble metal-based plasmonics, owing to smaller dissipative loss and better field confinement. However, a conventional way to excite the localized phonon resonance involves ion etching, which reduces the attainable quality factors (Q-factors) of the resonators. We show that by introducing a deep subwavelength layer of dielectric gratings on a phononic substrate, localized dipolar resonance and higher order modes with high Q-factors 96 and 195, respectively, can be excited. We further demonstrate, via experiments and simulations, that the resonant wavelength and field confinement can be controlled by coupling the localized hybrid mode with propagating surface phonon-polaritons. We also observed for the first time the coupling between a localized dipolar mode and a propagating higher-order surface phonon-polariton mode. The results will be useful in designing on-chip, low-loss, and highly integrated phononic devices in the infrared spectral domain.

    1 Introduction

    Squeezing photon energy into a deep subwavelength scale opens the path to strong light–matter interactions and has been extensively studied in plasmonics. Numerous applications have been demonstrated using noble metals and plasmonic graphene, which include waveguiding,13 refractive index sensing,46 perfect absorption,5,7,8 and Purcell factor enhancement,9,10 to name but a few. However, in the mid-infrared (mid-IR) spectral range, plasmonic materials suffer from either lack of confinement of the plasmon wave (in the case of noble metals) or high optical loss (in the case of graphene), which limit their practical applications. Recent advances in mid-IR phononic technologies provide an effective approach to address these challenges by using polar crystals as an alternative low-loss platform for highly integrated photonics. Such materials enable extremely confined phonon polaritons that exhibit lifetimes one order higher than almost all plasmonic counterparts.

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    Bo Qiang, Alexander M. Dubrovkin, Harish N. S. Krishnamoorthy, Qian Wang, Cesare Soci, Ying Zhang, Jinghua Teng, Qi Jie Wang. High Q-factor controllable phononic modes in hybrid phononic–dielectric structures[J]. Advanced Photonics, 2019, 1(2): 026001
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    Category: Research Articles
    Received: Jan. 29, 2019
    Accepted: Apr. 1, 2019
    Published Online: Apr. 24, 2019
    The Author Email: Wang Qi Jie (qjwang@ntu.edu.sg)