High sensitivity and low detection limit sensor based on a slotted nanobeam cavity
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2022-09-30 |
| Journal | Photonics Letters of Poland |
| Authors | Mohannad AlâHmoud, Rasha Alyahyan |
| Institutions | Imam Mohammad ibn Saud Islamic University |
| Citations | 2 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Diamond Nanophotonic Sensors
Section titled âTechnical Documentation & Analysis: Diamond Nanophotonic SensorsâExecutive Summary
Section titled âExecutive SummaryâThis analysis reviews the design and simulation of a high-sensitivity refractive index sensor based on a slotted photonic crystal nanobeam cavity (NPCC). The findings demonstrate a promising platform for advanced optofluidic and biosensing, which can be significantly enhanced by transitioning from silicon (Si) to MPCVD diamond.
- Ultra-High Performance: The simulated sensor achieved an ultra-high Quality Factor (Q) of $2.0 \times 10^{6}$ when optimized for a water environment ($n=1.333$).
- Exceptional Sensitivity: A high sensitivity (S) of 325 nm/RIU was demonstrated, leading to an extremely low Detection Limit (DL) of $2.4 \times 10^{-7}$ RIU.
- Mechanism: The design utilizes a 40 nm air slot to strongly localize the electric field, maximizing light-matter interaction with the analyte for efficient sensing.
- Small Mode Volume: The effective mode volume ($V_{eff} \sim 0.01 (\lambda/n)^{3}$) is small, making this platform ideal for single-particle detection in biosensing applications.
- Material Transition Opportunity: While the study used silicon ($n \approx 3.48$), 6CCVDâs high-purity MPCVD diamond offers superior thermal, chemical, and optical properties (wider transparency window) necessary for robust, high-power, and bio-compatible sensing devices.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the simulation results for the optimized slotted nanobeam cavity sensor:
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Maximum Quality Factor (Q) | $2.0 \times 10^{6}$ | Dimensionless | Optimized for water background ($n=1.333$) |
| Sensitivity (S) | 325 | nm/RIU | Wavelength shift per Refractive Index Unit |
| Detection Limit (DL) | $2.4 \times 10^{-7}$ | RIU | Minimum detectable RI change |
| Resonant Wavelength ($\lambda_0$) | $\sim 1554$ | nm | Fundamental mode, centered in telecom band |
| Photonic Band Gap (PBG) Range | 1270 to 1750 | nm | Operating range for the 1D nanobeam structure |
| Dielectric Material Refractive Index (n) | 3.48 | Dimensionless | Silicon (Si) used in simulation |
| Effective Mode Volume ($V_{eff}$) | $\sim 0.01 (\lambda/n)^{3}$ | Dimensionless | Indicates potential for single-particle detection |
| Optimal Cavity Length ($l$) | 235 | nm | Optimized for water background |
| Waveguide Thickness ($t$) | 220 | nm | Required thickness for nanophotonic fabrication |
| Slot Width | 40 | nm | Width of the air region confining the E-field |
Key Methodologies
Section titled âKey MethodologiesâThe sensor design and performance analysis relied on advanced computational modeling and structural optimization:
- Simulation Method: The structure was designed and analyzed using the three-dimensional finite-difference time-domain (3D-FDTD) method.
- Initial Design Parameters: The unperturbed 1D nanobeam photonic crystal was defined by a lattice constant ($a$) of 510 nm, air hole radius ($r$) of $0.365a$, and thickness ($t$) of 220 nm.
- PBG Alignment: Structural parameters were chosen to center the Photonic Band Gap (PBG) around the desired telecom wavelength ($\sim 1550$ nm).
- Q-Factor Optimization (Air): The cavity length ($l$) was scanned (481 nm to 492 nm) to achieve impedance matching between the waveguide mode and the Bloch mode, minimizing radiation loss and maximizing Q ($6.6 \times 10^{5}$).
- Q-Factor Optimization (Water): The structure was re-optimized for a water environment ($n=1.333$), requiring a reduced optimal cavity length ($l = 235$ nm) to achieve the maximum Q ($2.0 \times 10^{6}$).
- Sensing Measurement: Sensitivity (S) was calculated by monitoring the linear redshift of the resonant wavelength ($\Delta\lambda$) as the refractive index ($\Delta n$) was varied by simulating different seawater salinity concentrations (RI range: 1.33300 to 1.33851).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research demonstrates the potential of slotted nanobeam cavities for ultra-sensitive biosensing. While silicon was used in the simulation, diamond offers a superior platform for realizing these devices, especially for high-power or UV/Visible applications where Si is opaque. 6CCVD provides the necessary MPCVD diamond materials and fabrication services to transition this research from simulation to high-performance hardware.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research using a more robust platform, 6CCVD recommends the following materials:
| 6CCVD Material | Description | Application Advantage over Silicon |
|---|---|---|
| Optical Grade SCD | High-purity Single Crystal Diamond (SCD) | Lowest optical loss, highest thermal conductivity, enabling the highest possible Q-factors and high-power operation. Ideal for fundamental research. |
| High Purity PCD | Polycrystalline Diamond (PCD) | Excellent chemical inertness and mechanical hardness. Available in large formats (up to 125 mm) for high-throughput sensor arrays. |
| Boron-Doped Diamond (BDD) | Electrically conductive diamond | If the sensor requires integrated electrochemical detection or micro-heaters, BDD provides a stable, conductive electrode surface. |
Customization Potential
Section titled âCustomization PotentialâThe fabrication of nanophotonic devices requires precise control over material dimensions and surface quality. 6CCVDâs capabilities directly address the critical requirements of this slotted nanobeam design:
| Research Requirement | 6CCVD Capability | Specification |
|---|---|---|
| Ultra-thin Film Thickness | Custom SCD/PCD Growth | Thicknesses available from 0.1 ”m up to 500 ”m, perfectly matching the required 220 nm structure thickness. |
| Low Surface Roughness | Advanced Polishing Services | Guaranteed surface roughness (Ra) < 1 nm for SCD and < 5 nm for inch-size PCD, critical for minimizing scattering losses and maximizing Q-factor. |
| Integration & Interfacing | Custom Metalization | In-house deposition of Au, Pt, Pd, Ti, W, and Cu for creating electrical contacts, microfluidic interfaces, or bonding layers. |
| Large-Scale Arrays | Large Substrate Dimensions | Ability to supply PCD plates/wafers up to 125 mm diameter for scaling up sensor production. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in the application of MPCVD diamond for quantum, optical, and sensing technologies. We offer comprehensive support for projects involving:
- Material Selection: Assisting researchers in selecting the optimal diamond grade (SCD vs. PCD) based on required Q-factor, size, and operating wavelength.
- Design Translation: Consulting on how to translate silicon-based nanophotonic designs (like this slotted NPCC) to diamond, accounting for diamondâs lower refractive index ($n \approx 2.4$) and superior material properties.
- Biosensing Integration: Providing expertise on surface functionalization and integration strategies for optofluidic and bio-sensing applications, leveraging diamondâs inherent bio-compatibility.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
In this work, the three-dimensional finite-difference time-domain (3D-FDTD) method is used to design and analyze a refractive index sensor based on a slotted photonic crystal nanobeam cavity. These type of cavities support a high quality-factor and a small volume, and therefore is attractive for optical sensing. We demonstrate that when immersing our proposed sensor in water it can possess a high-quality factor of 2.0Ă10^6, high sensitivity of 325 nm/RIU, and a detection limit of 2.4Ă10^(-7) RIU. We believe that our proposed sensor is a promising candidate for potential applications sensing like in optofluidic- and bio-sensing. Full Text: PDF ReferencesE. Chow, A. Grot, L. Mirkarimi, M. Sigalas, G. Girolami, âUltracompact biochemical sensor built with two-dimensional photonic crystal microcavityâ, OSA Trends Opt. Photonics Ser. 97 909 (2004). CrossRef S. Kim, H-M. Kim, Y-H. Lee, âSingle nanobeam optical sensor with a high Q-factor and high sensitivityâ, Opt. Lett. 40 5351 (2015). CrossRef D-Q, Yang, B Duan, X, Liu, A-Q, Wang, X-G, Li, Y-F, Ji, âPhotonic Crystal Nanobeam Cavities for Nanoscale Optical Sensing: A Reviewâ, Micromachines 11 (2020). CrossRef P.B. Deotare, M.W. McCutcheon, I.W. Frank, M. Khan, M. LonÄar, âHigh quality factor photonic crystal nanobeam cavitiesâ, Appl. Phys. Lett. 94 121106 (2009). CrossRef P. Seidler, K. Lister, U. Drechsler, J. Hofrichter, T. Stöferle, âSlotted photonic crystal nanobeam cavity with an ultrahigh quality factor-to-mode volume ratioâ, Opt. Express 21 32468 (2013). CrossRef H. Choi, M. Heuck, D. Englund, âSelf-Similar Nanocavity Design with Ultrasmall Mode Volume for Single-Photon Nonlinearitiesâ, Phys. Rev. Lett. 118 223605 (2017). CrossRef M. Al-Hmoud, S. Bougouffa, âSimultaneous high Q/V-ratio and optimized far-field emission pattern in diamond slot-bridge nanobeam cavityâ, Results Phys. 26 104314 (2021). CrossRef Q. Quan (2014). CrossRef M.A. Butt, C. Tyszkiewicz, P. KarasiĆski, M. ZiÄba, D. Hlushchenko, T. Baraniecki, A. KaĆșmierczak, R. Piramidowicz, M. Guzik, A. Bachmatiuk, âDevelopment of a low-cost silica-titania optical platform for integrated photonics applicationsâ, Opt. Express 30 23678 (2022). CrossRef D-Q. Yang, B. Duan, X. Liu, A-Q. Wang, X-G. Li, Y-F. Ji, ""Photonic Crystal Nanobeam Cavities for Nanoscale Optical Sensing: A Reviewâ, Micromachines 72, 11 (2020). CrossRef Y.N. Zhang, Y. Zhao, R.Q Lv, âA review for optical sensors based on photonic crystal cavitiesâ, Sens. Actuators A: Phys. 233 374 (2015). CrossRef P. Lalanne, S. Mias, and J.P. Hugonin, âTwo physical mechanisms for boosting the quality factor to cavity volume ratio of photonic crystal microcavitiesâ, Opt. Express 12 458 (2004). CrossRef C. Sauvan, G. Lecamp, P. Lalanne, J.P Hugonin, âModal-reflectivity enhancement by geometry tuning in Photonic Crystal microcavitiesâ, Opt. Express 13 245 (2005). CrossRef J.T. Robinson, C. Manolatou, L. Chen, M. Lipson, âUltrasmall Mode Volumes in Dielectric Optical Microcavitiesâ, Phys. Rev. Lett. 95 143901 (2005). CrossRef S. Olyaee, M. Seifouri, R. Karami, A. Mohebzadeh-Bahabady, âDesigning low power and high contrast ratio all-optical NOT logic gate for using in optical integrated circuitsâ, Opt. Quantum Electron. 51 1 (2019). CrossRef