Citation

Noor, Kashfia and Islam, Mohammad Tariqul and Kirawanich, Phumin and Mahmood, Minhaz and Alenezi, Abdulmajeed M. and Misran, Norbahiah and Islam, Md. Shabiul (2026) Dual-function gold bowtie nanoantenna for NIR photothermal conversion and label-free plasmonic detection: A coupled FDTD-FEM design study. Materials Today Communications, 55. p. 115815. ISSN 23524928

Text Dual-function gold bowtie nanoantenna for NIR photothermal conversion and label-free plasmonic detection_ A coupled FDTD-FEM design study.pdf - Published Version Restricted to Repository staff only Download (3MB)

Abstract

Gold bowtie nanoantennas represent an architecturally compact solution for combining near-infrared photothermal conversion with label-free plasmonic molecular detection. This work reports the systematic computational co-optimization of both functions in a single geometry using a coupled FDTD-FEM multiphysics framework. A 75 nm arm length, 50 nm thickness, and 20 nm nanogap on SiO2 was identified as the optimal design for near-infrared operation, with the 808 nm excitation wavelength falling within the resonance absorption band where approximately 75% of peak absorption is retained. The optimized geometry yields a nanogap field intensity enhancement of ~718. The coupled thermal analysis establishes a photothermal operating envelope spanning 7.4 pW to 6.0 μW (ΔT = 16 K), with a realistic estimate of ~5.6 nW under aqueous substrate conditions. A physically calibrated dielectric perturbation (4 ×5 ×6 nm, n = 1.45) in the nanogap produces a 3 nm LSPR red shift, more than 30 × above standard spectrometer resolution, while the thermally induced blue shift (~0.4 nm) is directionally opposite and 7.5 × smaller, indicating intrinsic spectral orthogonality. Fabrication tolerance analysis quantifies the impact of EBL tip rounding and film roughness on achievable performance. These results provide a quantitative computational design blueprint for dual-function NIR plasmonic nanostructures.

Item Type:	Article
Uncontrolled Keywords:	Bowtie nanoantenna, FDTD
Subjects:	T Technology > TK Electrical engineering. Electronics Nuclear engineering > TK5101-6720 Telecommunication. Including telegraphy, telephone, radio, radar, television
Divisions:	Faculty of Artificial Intelligence & Engineering (FAIE)
Depositing User:	Ms Rosnani Abd Wahab
Date Deposited:	03 Sep 2026 07:02
Last Modified:	03 Sep 2026 07:02
URII:	http://shdl.mmu.edu.my/id/eprint/16632

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