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36 results on '"Farmakidis, Nikolaos"'

2. In-memory photonic dot-product engine with electrically programmable weight banks

Author

Zhou, Wen, Dong, Bowei, Farmakidis, Nikolaos, Li, Xuan, Youngblood, Nathan, Huang, Kairan, He, Yuhan, Wright, C. David, Pernice, Wolfram H. P., and Bhaskaran, Harish

Subjects
Physics - Applied Physics, Electrical Engineering and Systems Science - Systems and Control, Physics - Optics
Abstract

Electronically reprogrammable photonic circuits based on phase-change chalcogenides present an avenue to resolve the von-Neumann bottleneck; however, implementation of such hybrid photonic-electronic processing has not achieved computational success. Here, we achieve this milestone by demonstrating an in-memory photonic-electronic dot-product engine, one that decouples electronic programming of phase-change materials (PCMs) and photonic computation. Specifically, we develop non-volatile electronically reprogrammable PCM memory cells with a record-high 4-bit weight encoding, the lowest energy consumption per unit modulation depth (1.7 nJ per dB) for Erase operation (crystallization), and a high switching contrast (158.5%) using non-resonant silicon-on-insulator waveguide microheater devices. This enables us to perform parallel multiplications for image processing with a superior contrast-to-noise ratio (greater than 87.36) that leads to an enhanced computing accuracy (standard deviation less than 0.007). An in-memory hybrid computing system is developed in hardware for convolutional processing for recognizing images from the MNIST database with inferencing accuracies of 86% and 87%.

Published
2023
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4. All optical tunable RF filter using elemental antimony

Author

Aggarwal Samarth, Farmakidis Nikolaos, Dong Bowei, Lee June Sang, Wang Mengyun, Xu Zhiyun, and Bhaskaran Harish

Subjects
microwave photonics, all-optical filter, low-pass filter, thin-film antimony, Physics, QC1-999
Abstract

In the past decade, the proliferation of modern telecommunication technologies, including 5G, and the widespread adoption of the Internet-of-things (IoT) have led to an unprecedented surge in data generation and transmission. This surge has created an escalating demand for advanced signal processing capabilities. Microwave photonic (MWP) processors offer a promising solution to satisfy this unprecedented demand for data processing by capitalising on the high bandwidth and low latency achievable by optical systems. In this work, we introduce an integrated MWP processing unit for all-optical RF filtering using elemental antimony. We exploit the crystallisation dynamics of antimony to demonstrate a photonic leaky integrator, which is configured to operate as a first-order low-pass filter with a bandwidth of 300 kHz and ultra-compact footprint of 16 × 16 μm2. We experimentally demonstrate the implementation of such a filter as an envelope detector to demodulate an amplitude-modulated signal. Finally, a discussion on achieving bandwidth tunability is presented.

Published
2024
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5. Spatio-spectral control of coherent nanophotonics

Author

Lee June Sang, Farmakidis Nikolaos, Aggarwal Samarth, Dong Bowei, Zhou Wen, Pernice Wolfram H. P., and Bhaskaran Harish

Subjects
active photonics, photonic spatio-spectral reconfiguration, phase-change materials, Physics, QC1-999
Abstract

Fast modulation of optical signals that carry multidimensional information in the form of wavelength, phase or polarization has fueled an explosion of interest in integrated photonics. This interest however masks a significant challenge which is that independent modulation of multi-wavelength carrier signals in a single waveguide is not trivial. Such challenge is attributed to the longitudinal direction of guided-mode propagation, limiting the spatial separation and modulation of electric-field. Here, we overcome this using a single photonic element that utilizes active coherent (near) perfect absorption. We make use of standing wave patterns to exploit the spatial-degrees-of-freedom of in-plane modes and individually address elements according to their mode number. By combining the concept of coherent absorption in spatio-spectral domain with active phase-change nanoantennas, we engineer and test an integrated, reconfigurable and multi-spectral modulator operating within a single element. Our approach demonstrates for the first time, a non-volatile, wavelength-addressable element, providing a pathway for exploring the tunable capabilities in both spatial and spectral domains of coherent nanophotonics.

Published
2024
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6. Plasmonic nanogap enhanced phase change devices with dual electrical-optical functionality

Author

Farmakidis, Nikolaos, Youngblood, Nathan, Li, Xuan, Tan, James, Swett, Jacob L., Cheng, Zengguang, Wright, David C, Pernice, Wolfram HP, and Bhaskaran, Harish

Subjects
Physics - Optics, Physics - Applied Physics
Abstract

Modern-day computers use electrical signaling for processing and storing data which is bandwidth limited and power-hungry. These limitations are bypassed in the field of communications, where optical signaling is the norm. To exploit optical signaling in computing, however, new on-chip devices that work seamlessly in both electrical and optical domains are needed. Phase change devices can in principle provide such functionality, but doing so in a single device has proved elusive due to conflicting requirements of size-limited electrical switching and diffraction-limited photonic devices. Here, we combine plasmonics, photonics and electronics to deliver a novel integrated phase-change memory and computing cell that can be electrically or optically switched between binary or multilevel states, and read-out in either mode, thus merging computing and communications technologies.

Published
2018

9. Scalable Non‐Volatile Tuning of Photonic Computational Memories by Automated Silicon Ion Implantation

Author

Varri, Akhil, primary, Taheriniya, Shabnam, additional, Brückerhoff‐Plückelmann, Frank, additional, Bente, Ivonne, additional, Farmakidis, Nikolaos, additional, Bernhardt, Daniel, additional, Rösner, Harald, additional, Kruth, Maximilian, additional, Nadzeyka, Achim, additional, Richter, Torsten, additional, Wright, Christopher David, additional, Bhaskaran, Harish, additional, Wilde, Gerhard, additional, and Pernice, Wolfram H.P., additional

Published
2023
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12. Event-driven adaptive optical neural network

Author

Brückerhoff-Plückelmann, Frank, primary, Bente, Ivonne, additional, Becker, Marlon, additional, Vollmar, Niklas, additional, Farmakidis, Nikolaos, additional, Lomonte, Emma, additional, Lenzini, Francesco, additional, Wright, C. David, additional, Bhaskaran, Harish, additional, Salinga, Martin, additional, Risse, Benjamin, additional, and Pernice, Wolfram H. P., additional

Published
2023
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14. Designing Cultural Routes as a Tool of Responsible Tourism and Sustainable Local Development in Isolated and Less Developed Islands: The Case of Symi Island in Greece

Author

Fafouti, Aspasia E., primary, Vythoulka, Anastasia, additional, Delegou, Ekaterini T., additional, Farmakidis, Nikolaos, additional, Ioannou, Maria, additional, Perellis, Komninos, additional, Giannikouris, Antonis, additional, Kampanis, Nikolaos A., additional, Alexandrakis, George, additional, and Moropoulou, Antonia, additional

Published
2023
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23. Electronically Reconfigurable Photonic Switches Incorporating Plasmonic Structures and Phase Change Materials (Adv. Sci. 20/2022)

Author

Farmakidis, Nikolaos, primary, Youngblood, Nathan, additional, Lee, June Sang, additional, Feldmann, Johannes, additional, Lodi, Alessandro, additional, Li, Xuan, additional, Aggarwal, Samarth, additional, Zhou, Wen, additional, Bogani, Lapo, additional, Pernice, Wolfram HP, additional, Wright, C David, additional, and Bhaskaran, Harish, additional

Published
2022
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26. Antimony as a Programmable Element in Integrated Nanophotonics

Author

Aggarwal, Samarth, primary, Milne, Tara, additional, Farmakidis, Nikolaos, additional, Feldmann, Johannes, additional, Li, Xuan, additional, Shu, Yu, additional, Cheng, Zengguang, additional, Salinga, Martin, additional, Pernice, Wolfram HP, additional, and Bhaskaran, Harish, additional

Published
2022
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29. Ultrafast Switching in Integrated Photonics using Antimony

Author

Aggarwal, Samarth, primary, Milne, Tara, additional, Farmakidis, Nikolaos, additional, Feldmann, Johannes, additional, Li, Xuan, additional, Shu, Yu, additional, Cheng, Zengguang, additional, Salinga, Martin, additional, Pernice, Wolfram HP, additional, and Bhaskaran, Harish, additional

Published
2022
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30. Polarization-selective reconfigurability in hybridized-active-dielectric nanowires.

Author

June Sang Lee, Farmakidis, Nikolaos, Wright, C. David, and Bhaskaran, Harish

Subjects
*SEMICONDUCTOR nanowires, *NANOWIRES, *DIGITAL electronics, *PHASE change materials, *FANO resonance, *PHASE change memory, *PLANE wavefronts
Abstract

The article presents a study which explores the polarization-selective reconfigurability in hybridized-active-dielectric nanowires. It mentions that wavelength and polarization are two fundamental properties of light within which information can be encoded and (de)multiplexed. It demonstrate the ability to use polarization as a parameter to selectively modulate the conductance of individual nanowires within a multi-nanowire system.

Published
2022
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36. Towards closed-loop nanopatterning: quantifying ink dynamics in dip-pen nanolithography

Author

Farmakidis, Nikolaos

Subjects
Nanoscience, Dip, DPN, Fluid, Nanolithography, Pen, Transport
Abstract

Dip-pen nanolithography (DPN) is a scanning probe microscopy-based nanofabrication method that relies on a fluid-coated atomic force microscope probe for the deposition of material on a substrate with nanometer-scale resolution. The ability to tailor the structure and chemical composition of materials at the nanometer length scale is enabling in elds ranging from medical diagnostics to nano-electronics. While DPN is among the highest resolution additive manufacturing techniques to date, the conguration of ink on the probe and the process of ink transport are poorly understood. Specically, the inking and patterning procedures are susceptible to variations in the ambient environmental conditions and currently not all aspects of the processes are reliably controlled. Thus, a key challenge barring the widespread adoption of DPN beyond a research tool is reproducibility. We hypothesize that closed-loop control over the inking and patterning process could address this irreproducibility, however techniques to monitor the quantity and concentration of ink on the tip of the probe have not been yet developed. Here, we study the mechanics of atomic force microscope (AFM) probes throughout the inking and patterning process to understand if the behavior of the ink can be studied in situ. In particular, we develop an approach for conning ink to the tip of an AFM probe, which is critical for reliable patterning and modeling the mechanics of the probe. Then, we nd that the quantity of ink on an AFM probe can be determined in situ by observing the shift in the natural frequency of the probe. Finally, we show that this method allows for the observation and quantication of the ink deposited on a substrate, in real time. Collectively, these approaches lay the groundwork for a closed-loop implementation of DPN in which the inking and patterning processes are performed with drastically improved reliability. Given that these techniques are easily implemented on any commercial AFM, we expect that they could lead to new applications in the study of nanoscale soft materials.

Published
2016

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