Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing
We numerically and experimentally investigated the lateral coupling between photonic crystal (PhC) nanobeam (NB) cavities, pursuing high sensitivity and figure of merit (FOM) label-free biosensor. We numerically carried out 3D finite-difference time-domain (3D-FDTD) and the finite element method (F...
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MDPI AG
2015-10-01
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| Series: | Sensors |
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| Online Access: | http://www.mdpi.com/1424-8220/15/10/25868 |
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| author | Mohammad Tariq Yaseen Yi-Chun Yang Min-Hsiung Shih Yia-Chung Chang |
| author_facet | Mohammad Tariq Yaseen Yi-Chun Yang Min-Hsiung Shih Yia-Chung Chang |
| author_sort | Mohammad Tariq Yaseen |
| collection | DOAJ |
| description | We numerically and experimentally investigated the lateral coupling between photonic crystal (PhC) nanobeam (NB) cavities, pursuing high sensitivity and figure of merit (FOM) label-free biosensor. We numerically carried out 3D finite-difference time-domain (3D-FDTD) and the finite element method (FEM) simulations. We showed that when two PhC NB cavities separated by a small gap are evanescently coupled, the variation in the gap width significantly changes the coupling efficiency between the two coupled NB cavities and the resulting resonant frequencies split. Experimentally, we fabricated laterally-coupled PhC NB cavities using (InGaAsP) layer on the InP substrate. For sensing, we showed that the laterally coupled PhC NB cavities sensor exhibits higher sensitivity than the single PhC NB cavity. The higher sensitivity of laterally coupled PhC NB cavities is due to the strong evanescent coupling between nearby PhC NB cavities, which depends on the gap width and it is attributed to the large confinement of the electromagnetic field in the gap (air or liquid). As a result of the lateral coupling, both even (symmetric) and odd (asymmetric) modes exist. We show that even modes are more sensitive than odd modes. In addition, higher-order modes exhibit higher sensitivity. Hence, we characterized and examined the fabricated PhC NB cavity as a label-free biosensor, and it exhibits high figure of merit due to its high Q-factor. This illustrates a potentially useful method for optical sensing at nanoscale. |
| first_indexed | 2024-04-14T00:47:30Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-04-14T00:47:30Z |
| publishDate | 2015-10-01 |
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| series | Sensors |
| spelling | doaj.art-ef4e95d634c548b797d573a02aad79272022-12-22T02:21:58ZengMDPI AGSensors1424-82202015-10-011510258682588110.3390/s151025868s151025868Optimization of High-Q Coupled Nanobeam Cavity for Label-Free SensingMohammad Tariq Yaseen0Yi-Chun Yang1Min-Hsiung Shih2Yia-Chung Chang3Department of Engineering and System Science, National Tsing Hua University, Hsinchu 300, TaiwanResearch Centre for Applied Sciences, Academia Sinica, Taipei 115, TaiwanResearch Centre for Applied Sciences, Academia Sinica, Taipei 115, TaiwanResearch Centre for Applied Sciences, Academia Sinica, Taipei 115, TaiwanWe numerically and experimentally investigated the lateral coupling between photonic crystal (PhC) nanobeam (NB) cavities, pursuing high sensitivity and figure of merit (FOM) label-free biosensor. We numerically carried out 3D finite-difference time-domain (3D-FDTD) and the finite element method (FEM) simulations. We showed that when two PhC NB cavities separated by a small gap are evanescently coupled, the variation in the gap width significantly changes the coupling efficiency between the two coupled NB cavities and the resulting resonant frequencies split. Experimentally, we fabricated laterally-coupled PhC NB cavities using (InGaAsP) layer on the InP substrate. For sensing, we showed that the laterally coupled PhC NB cavities sensor exhibits higher sensitivity than the single PhC NB cavity. The higher sensitivity of laterally coupled PhC NB cavities is due to the strong evanescent coupling between nearby PhC NB cavities, which depends on the gap width and it is attributed to the large confinement of the electromagnetic field in the gap (air or liquid). As a result of the lateral coupling, both even (symmetric) and odd (asymmetric) modes exist. We show that even modes are more sensitive than odd modes. In addition, higher-order modes exhibit higher sensitivity. Hence, we characterized and examined the fabricated PhC NB cavity as a label-free biosensor, and it exhibits high figure of merit due to its high Q-factor. This illustrates a potentially useful method for optical sensing at nanoscale.http://www.mdpi.com/1424-8220/15/10/25868Photonic crystals (PhCs)nanobeam (NB) cavityfinite-difference time-domain (FDTD)label-free sensing |
| spellingShingle | Mohammad Tariq Yaseen Yi-Chun Yang Min-Hsiung Shih Yia-Chung Chang Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing Sensors Photonic crystals (PhCs) nanobeam (NB) cavity finite-difference time-domain (FDTD) label-free sensing |
| title | Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing |
| title_full | Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing |
| title_fullStr | Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing |
| title_full_unstemmed | Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing |
| title_short | Optimization of High-Q Coupled Nanobeam Cavity for Label-Free Sensing |
| title_sort | optimization of high q coupled nanobeam cavity for label free sensing |
| topic | Photonic crystals (PhCs) nanobeam (NB) cavity finite-difference time-domain (FDTD) label-free sensing |
| url | http://www.mdpi.com/1424-8220/15/10/25868 |
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