Low loss photonic nanocavity via dark magnetic dipole resonant mode near metal

Ning Liu,Brian Corbett,Greg Sun,Christophe Silien

doi:10.1038/s41598-018-35291-w

Ning Liu, Brian Corbett + Show 2 more

Open Access

https://doi.org/10.1038/s41598-018-35291-w

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Abstract

The dielectric-semiconductor-dielectric-metal 4 layered structure is a well-established configuration to support TM hybrid plasmonic modes, which have demonstrated significant advantages over pure photonic modes in structures without metal to achieve low loss resonant cavities at sub-diffraction limited volumes. The photonic modes with TE characteristics supported by the same 4 layered structure, on the other hand, are less studied. Here we show that a low loss photonic mode with TE01 characteristics exists in the dielectric-semiconductor-dielectric-metal 4 layered structure if a truncated cylindrical disk is chosen as the semiconductor core. This mode exhibits the lowest cavity loss among all resonant modes, including both pure photonic and hybrid plasmonic modes, at cavity radius <150 nm and within the wavelength range 620 nm to 685 nm, with a footprint ~0.83 (λ/2neff)2, physical size ~0.47 (λ/2neff)3 and a mode volume down to 0.3 (λ/2neff)3. The low cavity loss of this TE01 mode is attributed to its substantially reduced radiation loss to the far field by the creation of image charges through the metal response. Because of the low mode penetration in the metal, this photonic mode show equally low cavity loss near industry relevant metals such as Cu. Our study demonstrates an alternative to hybrid plamonic modes and metallo-dielectric modes to achieve low loss cavities with extremely small footprints.

Highlights

Photonic lasers are one of the key components in integrated photonic circuits[1]
Different from the well-studied hybrid plasmonic mode, which has mostly transverse magnetic (TM) characteristics, the photonic mode that co-exists in this type of structure, which has transverse electric (TE) characteristics, on the other hand, has received little attention, other than being used as the comparison to the hybrid plasmonic mode to show that the effective refractive index in the photonic case is lower than that in the hybrid plasmonic mode[12]
We focus our attention on the photonic mode that exists in the dielectric-semiconductordielectric-metal 4-layered structure and demonstrate how this photonic mode can be used to achieve low loss, sub-diffraction nanocavities with very small footprints

Summary

Introduction

Photonic lasers are one of the key components in integrated photonic circuits[1]. High integration densities of lasers on a chip will be needed for intra-chip communications. Conventional optical cavities can hardly achieve lasing at dimensions around (λ/2neff)[3] To overcome this limitation, metal coated photonic cavities, termed metallo-dielectric cavities, have been exploited to confine light into a diffraction limited volume of (λ/2neff)[3 3,4,5,6,7]. People have been looking into hybrid plasmonic modes, which exist at the dielectricsemiconductor-dielectric-metal interface, to achieve lasing at deep subwavelength scale with low propagation loss, promising substantial increase in packing density of optical components in integrated circuits. We focus our attention on the photonic mode that exists in the dielectric-semiconductordielectric-metal 4-layered structure and demonstrate how this photonic mode can be used to achieve low loss, sub-diffraction nanocavities with very small footprints

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