Sahil Dagli

All Publications

• Very-large-scale integrated high quality factor nanoantenna pixels. Nature nanotechnology Dolia, V., Balch, H. B., Dagli, S., Abdollahramezani, S., Carr Delgado, H., Moradifar, P., Chang, K., Stiber, A., Safir, F., Lawrence, M., Hu, J., Dionne, J. A. 2024

  Abstract

  Metasurfaces precisely control the amplitude, polarization and phase of light, with applications spanning imaging, sensing, modulation and computing. Three crucial performance metrics of metasurfaces and their constituent resonators are the quality factor (Q factor), mode volume (Vm) and ability to control far-field radiation. Often, resonators face a trade-off between these parameters: a reduction in Vm leads to an equivalent reduction in Q, albeit with more control over radiation. Here we demonstrate that this perceived compromise is not inevitable: high quality factor, subwavelength Vm and controlled dipole-like radiation can be achieved simultaneously. We design high quality factor, very-large-scale-integrated silicon nanoantenna pixels (VINPix) that combine guided mode resonance waveguides with photonic crystal cavities. With optimized nanoantennas, we achieve Q factors exceeding 1,500 with Vm less than 0.1 ( λ / n air ) 3 . Each nanoantenna is individually addressable by free-space light and exhibits dipole-like scattering to the far-field. Resonator densities exceeding a million nanoantennas per cm2 can be achieved. As a proof-of-concept application, we show spectrometer-free, spatially localized, refractive-index sensing, and fabrication of an 8 mm × 8 mm VINPix array. Our platform provides a foundation for compact, densely multiplexed devices such as spatial light modulators, computational spectrometers and in situ environmental sensors.

  View details for DOI 10.1038/s41565-024-01697-z

  View details for PubMedID 38961248

  View details for PubMedCentralID 10971570

• Rapid genetic screening with high quality factor metasurfaces. Nature communications Hu, J., Safir, F., Chang, K., Dagli, S., Balch, H. B., Abendroth, J. M., Dixon, J., Moradifar, P., Dolia, V., Sahoo, M. K., Pinsky, B. A., Jeffrey, S. S., Lawrence, M., Dionne, J. A. 2023; 14 (1): 4486

  Abstract

  Genetic analysis methods are foundational to advancing personalized medicine, accelerating disease diagnostics, and monitoring the health of organisms and ecosystems. Current nucleic acid technologies such as polymerase chain reaction (PCR) and next-generation sequencing (NGS) rely on sample amplification and can suffer from inhibition. Here, we introduce a label-free genetic screening platform based on high quality (high-Q) factor silicon nanoantennas functionalized with nucleic acid fragments. Each high-Q nanoantenna exhibits average resonant quality factors of 2,200 in physiological buffer. We quantitatively detect two gene fragments, SARS-CoV-2 envelope (E) and open reading frame 1b (ORF1b), with high-specificity via DNA hybridization. We also demonstrate femtomolar sensitivity in buffer and nanomolar sensitivity in spiked nasopharyngeal eluates within 5 minutes. Nanoantennas are patterned at densities of 160,000 devices per cm2, enabling future work on highly-multiplexed detection. Combined with advances in complex sample processing, our work provides a foundation for rapid, compact, and amplification-free molecular assays.

  View details for DOI 10.1038/s41467-023-39721-w

  View details for PubMedID 37495593

  View details for PubMedCentralID PMC10372074

• Through thick and thin: how optical cavities control spin. Nanophotonics (Berlin, Germany) Dixon, J., Pan, F., Moradifar, P., Bordoloi, P., Dagli, S., Dionne, J. 2023; 12 (14): 2779-2788

  Abstract

  When light interacts with matter by means of scattering and absorption, we observe the resulting color. Light also probes the symmetry of matter and the result is encoded in its polarization. In the special case of circularly-polarized light, which is especially relevant in nonlinear optics, quantum photonics, and physical chemistry, a critical dimension of symmetry is along the longitudinal direction. We examine recent advances in controlling circularly-polarized light and reveal that the commonality in these advances is in judicious control of longitudinal symmetry. In particular, in the use of high quality-factor modes in dielectric metasurfaces, the finite thickness can be used to tune the modal profile. These symmetry considerations can be applied in multiplexed optical communication schemes, deterministic control of quantum emitters, and sensitive detection of the asymmetry of small molecules.

  View details for DOI 10.1515/nanoph-2023-0175

  View details for PubMedID 39635484

  View details for PubMedCentralID PMC11501721

• Nanophotonics for a sustainable future PHYSICS TODAY Dionne, J. A., Dagli, S., Shalaev, V. M. 2023; 76 (6): 24-31

  View details for DOI 10.1063/PT.3.5254

  View details for Web of Science ID 001054531900010

• Through thick and thin: how optical cavities control spin NANOPHOTONICS Dixon, J., Pan, F., Moradifar, P., Bordoloi, P., Dagli, S., Dionne, J. 2023

  View details for DOI 10.1515/nanoph-2023-0175

  View details for Web of Science ID 000982262200001

• Universal Narrowband Wavefront Shaping with High Quality Factor Meta-Reflect-Arrays. Nano letters Lin, L., Hu, J., Dagli, S., Dionne, J. A., Lawrence, M. 2023

  Abstract

  Optical metasurfaces offer unprecedented flexibility in light wave manipulation but suffer weak resonant enhancement. Tackling this problem, we experimentally unveil a new phase gradient metasurface platform made entirely from individually addressable high quality factor (high-Q) silicon meta-atoms. Composed of pairs of nearly identical nanoblocks, these meta-atoms support dipolar-guided-mode resonances that, due to the controlled suppression of radiation loss, serve as highly sensitive phase pixels when placed above a mirror. A key novelty of this platform lies in the vanishingly small structural perturbations needed to produce universal phase fronts. Having fabricated elements with Q-factor 380 and spaced by lambda/1.2, we achieve strong beam steering, up to 59% efficient, to angles 32.3°, 25.3°, and 20.9°, with variations in nanoantenna volume fractions across the metasurfaces of ≤2.6%, instead of >50% required by traditional versions. Aside from extreme sensitivity, the metasurfaces exhibit near-field intensity enhancement over 1000*. Taken together, these properties represent an exciting prospect for dynamic and nonlinear wave shaping.

  View details for DOI 10.1021/acs.nanolett.2c04621

  View details for PubMedID 36745385

• High-Quality-Factor Silicon-on-Lithium Niobate Metasurfaces for Electro-optically Reconfigurable Wavefront Shaping. Nano letters Klopfer, E., Dagli, S., Barton, D. 3., Lawrence, M., Dionne, J. A. 1800

  Abstract

  Dynamically reconfigurable metasurfaces promise compact and lightweight spatial light modulation for many applications, including LiDAR, AR/VR, and LiFi systems. Here, we design and computationally investigate high-quality-factor silicon-on-lithium niobate metasurfaces with electrically driven, independent control of its constituent nanobars for full phase tunability with high tuning efficiency. Free-space light couples to guided modes within each nanobar via periodic perturbations, generating quality factors exceeding 30,000 while maintaining a bar spacing of

  View details for DOI 10.1021/acs.nanolett.1c04723

  View details for PubMedID 35112873

• Rapid genetic screening with high quality factor metasurfaces. ArXiv Hu, J., Safir, F., Chang, K., Dagli, S., Balch, H. B., Abendroth, J. M., Dixon, J., Moradifar, P., Dolia, V., Sahoo, M. K., Pinsky, B. A., Jeffrey, S. S., Lawrence, M., Dionne, J. A. 2021

  Abstract

  Genetic analysis methods are foundational to advancing personalized and preventative medicine, accelerating disease diagnostics, and monitoring the health of organisms and ecosystems. Current nucleic acid technologies such as polymerase chain reaction (PCR), next-generation sequencing (NGS), and DNA microarrays rely on fluorescence and absorbance, necessitating sample amplification or replication and leading to increased processing time and cost. Here, we introduce a label-free genetic screening platform based on high quality (high-Q) factor silicon nanoantennas functionalized with monolayers of nucleic acid fragments. Each nanoantenna exhibits substantial electromagnetic field enhancements with sufficiently localized fields to ensure isolation from neighboring resonators, enabling dense biosensor integration. We quantitatively detect complementary target sequences using DNA hybridization simultaneously for arrays of sensing elements patterned at densities of 160,000 pixels per cm$^2$. In physiological buffer, our nanoantennas exhibit average resonant quality factors of 2,200, allowing detection of two gene fragments, SARS-CoV-2 envelope (E) and open reading frame 1b (ORF1b), down to femtomolar concentrations. We also demonstrate high specificity sensing in clinical nasopharyngeal eluates within 5 minutes of sample introduction. Combined with advances in biomarker isolation from complex samples (e.g., mucus, blood, wastewater), our work provides a foundation for rapid, compact, amplification-free and high throughput multiplexed genetic screening assays spanning medical diagnostics to environmental monitoring.

  View details for PubMedID 34671699

  View details for PubMedCentralID PMC8528080

• High-Q nanophotonics: sculpting wavefronts with slow light NANOPHOTONICS Barton, D., Hu, J., Dixon, J., Klopfer, E., Dagli, S., Lawrence, M., Dionne, J. 2021; 10 (1): 83–88

  View details for DOI 10.1515/nanoph-2020-0510

  View details for Web of Science ID 000597359300007