Research Article
Band Gap Engineering and Light Localization in Si and InP Based Three-dimensional Photonic Crystals
Fairuz Aniqa Salwa*
,
Jahirul Khandaker,
Mohammad Mominur Rahman Islam,
Muhammad Obaidur Rahman,
Md. Abdul Mannan Chowdhury
Issue:
Volume 13, Issue 1, March 2025
Pages:
1-16
Received:
29 July 2025
Accepted:
14 August 2025
Published:
29 August 2025
Abstract: We demonstrated photonic band diagrams of three-dimensional photonic crystals composed of InP and Si for four different lattice types:- face-centered cubic (FCC), inverse opal, woodpile, and diamond structures, making 12 combinations. The Si-based FCC and inverse opal lattices exhibited no photonic band gaps (PBGs). Then, the InP-based inverse opal demonstrated small, significant 1% PBGs. After that the woodpile lattices of dielectric rods in air and diamond lattices of air voids in dielectric for both InP and Si showed large complete PBGS, enabling better photon control. A point defect was introduced in the inverse opal lattice of air voids in Si and InP background. The Si lattice didn’t have a cavity mode, as it had no PBGs. The InP inverse opal lattice localized light effectively within its defect cavity using its 1% PBG, enabling it to act as a resonator and reflector. Light emission was inhibited in the surrounding photonic crystal region, as it was trapped in the defect cavity. The results obtained here are an important step towards the complete control of photons in photonic crystals.
Abstract: We demonstrated photonic band diagrams of three-dimensional photonic crystals composed of InP and Si for four different lattice types:- face-centered cubic (FCC), inverse opal, woodpile, and diamond structures, making 12 combinations. The Si-based FCC and inverse opal lattices exhibited no photonic band gaps (PBGs). Then, the InP-based inverse opal...
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Research Article
Optical Response and Light Propagation in Bimetallic Quantum Dot Ag@Au Core-shell Nanocomposite Embedded in Non-absorptive Host Medium
Gashaw Beyene Kassahun*
Issue:
Volume 13, Issue 1, March 2025
Pages:
17-26
Received:
11 October 2025
Accepted:
21 October 2025
Published:
28 November 2025
DOI:
10.11648/j.ajop.20251301.12
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Abstract: In this research work, optical and dispersion responses of bimetallic quantum dot Ag@Au core-shell nanostructures embedded in the non-absorptive host-medium, along with the propagation of slow and fast light waves through these structures, have been investigated. The local field enhancement factor, absorption coefficient, refractive index and group velocity were studied by engineering silver (Ag) as a core and gold (Au) as a shell. The study is based on the quasi-static approximation of classical electrodynamics for composite radii ranging from 6 to 10 nm. Within this quantum dot configuration, two sets of plasmonic resonances were observed in the visible spectral region, corresponding to the two interfaces of the core–shell geometry. The optical properties of the composite were found to depend on factors such as core size, shell thickness, overall composite size, filling factor, and the dielectric function of the host medium. The two plasmonic resonances become closer and more intense as the composite size decreases for a fixed core size, while they shift in opposite directions. Moreover, the resonance peak intensity decreases as the core size increases for a fixed composite size. For optimized core/composite dimensions, shell thickness, and other parameter values, these Ag@Au core–shell nanostructures are promising for diverse applications including photocatalysis, biomedicine, nano-optoelectronics, security technologies, and optical communication.
Abstract: In this research work, optical and dispersion responses of bimetallic quantum dot Ag@Au core-shell nanostructures embedded in the non-absorptive host-medium, along with the propagation of slow and fast light waves through these structures, have been investigated. The local field enhancement factor, absorption coefficient, refractive index and group...
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