Strongly Confining Light with Air-Mode Cavities in Inverse Rod-Connected Diamond Photonic Crystals

Three-dimensional dielectric optical crystals with a high index show a complete photonic bandgap (PBG), blocking light propagation in all directions. We show that this bandgap can be used to trap light in low-index defect cavities, leading to strongly enhanced local fields. We compute the band struc...

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Bibliographic Details
Published inCrystals (Basel) Vol. 12; no. 3; p. 303
Main Authors Taverne, Mike P. C., Ho, Ying-Lung D., Rarity, John G.
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.03.2022
Subjects
Broadband
Crystal defects
Diamonds
Dipoles
Electric fields
Holes
Investigations
microcavities
Photonic band gaps
photonic bandgap materials
Photonic crystals
Point defects
Quantum dots
Simulation
Time domain analysis
Unit cell
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Summary:Three-dimensional dielectric optical crystals with a high index show a complete photonic bandgap (PBG), blocking light propagation in all directions. We show that this bandgap can be used to trap light in low-index defect cavities, leading to strongly enhanced local fields. We compute the band structure and optimize the bandgap of an inverse 3D rod-connected diamond (RCD) structure, using the plane-wave expansion (PWE) method. Selecting a structure with wide bandgap parameters, we then add air defects at the center of one of the high-index rods of the crystal and study the resulting cavity modes by exciting them with a broadband dipole source, using the finite-difference time-domain (FDTD) method. Various defect shapes were studied and showed extremely small normalized mode volumes (Veff) with long cavity storage times (quality factor Q). For an air-filled spherical cavity of radius 0.1 unit-cell, a record small-cavity mode volume of Veff~2.2 × 10−3 cubic wavelengths was obtained with Q~3.5 × 106.
ISSN:2073-4352
2073-4352
DOI:10.3390/cryst12030303