Analysis and Design of Refractive Index Biosensors Based on Single Silicon Nanobeam Cavity
Single silicon nanobeam photonic crystal cavity based sensors are systematically analyzed and designed. By using perturbation theory and numerical simulations, both dielectric-mode and air-mode cavities are extensively investigated in terms of sensitivity (<inline-formula><tex-math notation...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IEEE
2016-01-01
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| Series: | IEEE Photonics Journal |
| Subjects: | |
| Online Access: | https://ieeexplore.ieee.org/document/7579554/ |
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| Summary: | Single silicon nanobeam photonic crystal cavity based sensors are systematically analyzed and designed. By using perturbation theory and numerical simulations, both dielectric-mode and air-mode cavities are extensively investigated in terms of sensitivity (<inline-formula><tex-math notation="LaTeX">$S$</tex-math></inline-formula>), figure of merit (<inline-formula><tex-math notation="LaTeX">${\rm FOM}$</tex-math></inline-formula>), detection limit (<inline-formula> <tex-math notation="LaTeX">$\text{DL}$</tex-math></inline-formula>), footprint size, and coupling scheme. The analytical study reveals a sensitivity limit of 1176 nm/RIU and a maximum figure of merit of 5070 for nanobeam cavity based sensors, due to the absorption of light near 1550 nm wavelength. when water is used as the carrier fluid. Design of high <inline-formula><tex-math notation="LaTeX">${\rm FOM}$</tex-math></inline-formula> (<inline-formula> <tex-math notation="LaTeX">$>$</tex-math></inline-formula> 4800) nanobeam cavities is demonstrated with <inline-formula><tex-math notation="LaTeX">$S$</tex-math></inline-formula> of 291 and 232 nm/RIU for air modes and dielectric modes, respectively. The calculation results indicate that on a 220-nm-thick-silicon SOI platform, it is possible to design a nanobeam cavity based biosensor with <inline-formula><tex-math notation="LaTeX">$\text{DL}$ </tex-math></inline-formula> on the order of <inline-formula><tex-math notation="LaTeX">$4 \times 10^{-6}$</tex-math> </inline-formula> RIU, insertion loss of −30 dB, and cavity length less than <inline-formula> <tex-math notation="LaTeX">$40a$</tex-math></inline-formula> (<inline-formula><tex-math notation="LaTeX">$a$</tex-math> </inline-formula> is the lattice constant). To approach the absorption bounded <inline-formula> <tex-math notation="LaTeX">$\text{DL}$</tex-math></inline-formula>, the presented design is adequate when analyte absorption dominates the loss, regardless if it is for dielectric modes or air modes. These results would be conducive to clarification of the confusion on the priority of air mode and dielectric mode in designing nanobeam cavities based sensors, as well as recent considerable efforts to maximize <inline-formula><tex-math notation="LaTeX">$S$</tex-math> </inline-formula> and <inline-formula><tex-math notation="LaTeX">${\rm FOM}$</tex-math></inline-formula>. |
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| ISSN: | 1943-0655 |