Mr. Ahasan Ahamed Profile

Ahasan Ahamed

at Univ of California Davis

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Author

Publications (13)

Proceedings Article | 12 March 2024 Presentation + Paper

On-chip hyperspectral detectors for fluorescence lifetime imaging

Ahasan Ahamed, Amita Rawat, Lisa McPhillips, Laura Marcu, M. Saif Islam

Proceedings Volume 12853, 1285304 (2024) https://doi.org/10.1117/12.3002476

KEYWORDS: Sensors, Fluorescence lifetime imaging, Avalanche photodetectors, External quantum efficiency, Fluorescence, Tissues, Emission wavelengths, Quantum detection, Photonic nanostructures, Fluorescence spectroscopy

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Fluorescence Lifetime Imaging (FLIM) is a powerful technique that measures the decay time of fluorophores present in tissue samples alluding to their constituent molecules. FLIM has gained popularity in biomedical imaging for applications such as detecting cancerous tumors, surgical guidance, etc. However, conventional FLIM systems are limited by a reduced number of spectral bands and long acquisition time. Moreover, the large footprint, complexity, and cost of the instrumentation make it difficult for clinical applications. In this paper, we demonstrate a reconstruction-based hyperspectral detector that can resolve decay time and intensities in broad spectral ranges while providing high sensitivity, high gain, and fast response time. The hyperspectral detector is comprised of an array of efficient, ultrafast avalanche photodetectors integrated with nanophotonic structures. We utilize different nanostructures in the detectors to modulate light-matter interactions in spectral channels. This allows us to computationally reconstruct the spectral profile of the incoming fluorescence spectrum without the need for additional filters or dispersive optics. Also, the nanophotonic structures enhance efficiency (by a factor of 2 to 10 over different wavelengths) while providing fast response time. An innovative detector design has been employed to reduce the breakdown of the avalanche photodetectors to -7.8V while maintaining high gain (~50) across the spectral range. Therefore, enabling low light detection with a high signal-to-noise ratio for FLIM applications. Added spectral channels would provide valuable information about tissue materials, morphology, and disease diagnosis. Such innovative hyperspectral sensors can now be integrated on-chip capable of miniaturizing the FLIM system and making it a commercially viable tool for clinical use. This technology has the potential to revolutionize the current FLIM system with improved detection capabilities opening doors for new horizons.

Proceedings Article | 9 March 2024 Presentation

Precision photon manipulation in photodetectors for AI-driven ultrafast sensing and imaging

M. Saif Islam, Ahasan Ahamed, Lisa McPhillips, Amita Rawat

Proceedings Volume PC12895, PC128950B (2024) https://doi.org/10.1117/12.3007784

KEYWORDS: Ultrafast imaging, Photodetectors, Light absorption, Biological imaging, Semiconductors, Miniature imaging systems, Imaging spectroscopy, Film thickness, Ultrafast phenomena, Spectroscopy

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Proceedings Article | 8 March 2024 Presentation + Paper

DC linearity and absorption efficiency enhancement by introducing photon-trapping microstructures into avalanche photodetectors

Lisa McPhillips, Amita Rawat, Ahasan Ahamed, M. Saif Islam

Proceedings Volume 12895, 128950G (2024) https://doi.org/10.1117/12.3003649

KEYWORDS: Avalanche photodetectors, Light sources and illumination, Light absorption, Photodiodes, External quantum efficiency, Photonic microstructures, Semiconducting wafers, Doping, Silicon, Quantum devices

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Proceedings Article | 8 March 2024 Presentation + Paper

Scalable photodetector design with sub-picosecond response time

Ahasan Ahamed, Amita Rawat, Lisa McPhillips, Shih-Yuan Wang, M. Saif Islam

Proceedings Volume 12895, 128950H (2024) https://doi.org/10.1117/12.3002441

KEYWORDS: Picosecond phenomena, Photodetectors, Electric fields, Photodiodes, Design, PIN photodiodes, Doping, Silicon, Dopants, Sensors

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Proceedings Article | 5 October 2023 Presentation + Paper

Advancing multi-dimensional vision: AI-driven imaging using unique photodetectors with integrated surface nanostructures

Ahasan Ahamed, Weiwei Wang, Amita Rawat, Lisa McPhillips, Ekaterina Ponizovskaya Devine, Shih-Yuan Wang, Zhi Ding, M. Saif Islam

Proceedings Volume 12651, 1265104 (2023) https://doi.org/10.1117/12.2682104

KEYWORDS: Nanostructures, Photodetectors, Artificial intelligence, External quantum efficiency, Spectrometers, Spatial resolution, Nanostructuring, Laser nanostructuring, Biomedical optics, Temporal resolution

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SPIE Journal Paper | 24 July 2023 Open Access

Achieving higher photoabsorption than group III-V semiconductors in ultrafast thin silicon photodetectors with integrated photon-trapping surface structures

Wayesh Qarony, Ahmed Mayet, Ekaterina Ponizovskaya-Devine, Soroush Ghandiparsi, Cesar Bartolo-Perez, Ahasan Ahamed, Amita Rawat, Hasina Mamtaz, Toshishige Yamada, Shih-Yuan Wang, M. Saif Islam

APN, Vol. 2, Issue 05, 056001, (July 2023) https://doi.org/10.1117/12.10.1117/1.APN.2.5.056001

KEYWORDS: Silicon, Light absorption, Photodetectors, Ultrafast phenomena, Gallium arsenide, Absorption, Quantum efficiency, Group III-V semiconductors, Fabrication, Film thickness

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SPIE Journal Paper | 20 March 2023

Single microhole per pixel for thin Ge-on-Si complementary metal-oxide semiconductor image sensor with enhanced sensitivity up to 1700 nm

Ekaterina Ponizovskaya-Devine, Ahmed S. Mayet, Amita Rawat, Ahasan Ahamed, Shih-Yuan Wang, Aly F. Elrefaie, Toshishige Yamada, M. Saif Islam

JNP, Vol. 17, Issue 01, 016012, (March 2023) https://doi.org/10.1117/12.10.1117/1.JNP.17.016012

KEYWORDS: Germanium, Crosstalk, Tunable filters, Simulations, Optical filters, Image sensors, Silicon, Light absorption, Quantum efficiency, Near infrared

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Proceedings Article | 3 October 2022 Presentation + Paper

Wavelength selective silicon avalanche photodiodes with controlled wide spectral gain by integrating photon-trapping microstructures

Amita Rawat, Ahasan Ahamed, Lisa Mcphillips, Busra Ergul-Yilmaz, Cesar Bartolo-Perez, Shih-Yuan Wang, M. Saif Islam

Proceedings Volume 12200, 1220005 (2022) https://doi.org/10.1117/12.2637146

KEYWORDS: External quantum efficiency, Silicon, Absorption, Avalanche photodetectors, Quantum efficiency, Avalanche photodiodes, Doping, Scanning electron microscopy, Photonic microstructures, Visual communications

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Proceedings Article | 5 March 2022 Presentation + Paper

Optimizing the light penetration depth in APDs and SPADs for high gain-bandwidth and ultra-wide spectral response

Ahasan Ahamed, Cesar Bartolo-Perez, Ahmed Sulaiman Mayet, Soroush Ghandiparsi, Gerard Ariño-Estrada, Xiangnan Zhou, Julien Bec, Shih-Yuan Wang, Laura Marcu, M. Saif Islam

Proceedings Volume 12009, 1200905 (2022) https://doi.org/10.1117/12.2610526

KEYWORDS: Avalanche photodetectors, Nanostructures, Absorption, Silicon, Photonic nanostructures, Sensors, Nanostructuring, Fluorescence lifetime imaging, Modulation, Avalanche photodiodes

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Proceedings Article | 2 March 2022 Presentation + Paper

Reconstruction-based spectroscopy using CMOS image sensors with random photon-trapping nanostructure per sensor

Ahasan Ahamed, Cesar Bartolo-Perez, Ahmed Mayet, Soroush Ghandiparsi, Lisa McPhillips, Shih-Yuan Wang, M. Saif Islam

Proceedings Volume 11971, 1197106 (2022) https://doi.org/10.1117/12.2610527

KEYWORDS: Spectrometers, Photodiodes, Nanostructures, Sensors, Spectroscopy, Silicon, Quantum efficiency, Biomedical optics, Photonic nanostructures, Fluorescence lifetime imaging

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Proceedings Article | 3 August 2021 Paper

Controlling light penetration depth to amplify the gain in ultra-fast silicon APDs and SPADs using photon-trapping nanostructures

Ahasan Ahamed, Cesar Bartolo-Perez, Ahmed Sulaiman Mayet, Soroush GhandiParsi, Xiangnan Zhou, Julien Bec, Nibir K. Dhar, Ekaterina P. Devine, Shih-Yuan Wang, Gerard Ariño-Estrada, Laura Marcu, M. Saif Islam

Proceedings Volume 11800, 118000F (2021) https://doi.org/10.1117/12.2597835

KEYWORDS: Absorption, Silicon, Avalanche photodetectors, Photonic nanostructures, Nanostructures, Avalanche photodiodes, Etching, Photonic devices, Photodiodes, Sensors

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Proceedings Article | 1 August 2021 Paper

Surface nanostructures for engineering spectral responsivity in imaging sensor pixels for combatting deepfakes

Lisa McPhillips, Ahasan Ahamed, Cesar Bartolo-Perez, M. Saif Islam

Proceedings Volume 11841, 118410G (2021) https://doi.org/10.1117/12.2597841

KEYWORDS: Video, Cameras, Spectroscopy, Computer programming, Absorption, Photodiodes, Neural networks, Nanostructures, Optical sensors, Software development

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Proceedings Article | 5 March 2021 Presentation + Paper

Controlling the photon absorption characteristics in avalanche photodetectors for high resolution biomedical imaging

Cesar Bartolo-Perez, Soroush Ghandiparsi, Ahmed Mayet, Ahasan Ahamed, Wayesh Qarony, Hilal Cansizoglu, Yang Gao, Shih-Yuan Wang, Simon Cherry, M. Saif Islam, Gerard Ariño-Estrada

Proceedings Volume 11658, 116580B (2021) https://doi.org/10.1117/12.2577805

KEYWORDS: Absorption, Avalanche photodetectors, Image resolution, Photodetectors, Finite-difference time-domain method, Ultrafast phenomena, TCAD, Structural design, Spatial resolution, Single photon

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Showing 5 of 13 publications

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