More Like this

1. All-optical ultrafast ReLU function for energy-efficient nanophotonic deep learning

   https://doi.org/10.1515/nanoph-2022-0137  

   Li, Gordon H.Y.; Sekine, Ryoto; Nehra, Rajveer; Gray, Robert M.; Ledezma, Luis; Guo, Qiushi; Marandi, Alireza (May 2022, Nanophotonics)

   Abstract In recent years, the computational demands of deep learning applications have necessitated the introduction of energy-efficient hardware accelerators. Optical neural networks are a promising option; however, thus far they have been largely limited by the lack of energy-efficient nonlinear optical functions. Here, we experimentally demonstrate an all-optical Rectified Linear Unit (ReLU), which is the most widely used nonlinear activation function for deep learning, using a periodically-poled thin-film lithium niobate nanophotonic waveguide and achieve ultra-low energies in the regime of femtojoules per activation with near-instantaneous operation. Our results provide a clear and practical path towards truly all-optical, energy-efficient nanophotonic deep learning. 

   more » « less
2. Adaptive Particle Filtering for Fault Detection in Partially-Observed Boolean Dynamical Systems

   https://doi.org/10.1109/TCBB.2018.2880234  

   Bahadorinejad, Arghavan; Imani, Mahdi; Braga-Neto, Ulisses (November 2018, IEEE/ACM Transactions on Computational Biology and Bioinformatics)

   We propose a novel methodology for fault detection and diagnosis in partially-observed Boolean dynamical systems (POBDS). These are stochastic, highly nonlinear, and derivative- less systems, rendering difficult the application of classical fault detection and diagnosis methods. The methodology comprises two main approaches. The first addresses the case when the normal mode of operation is known but not the fault modes. It applies an innovations filter (IF) to detect deviations from the nominal normal mode of operation. The second approach is applicable when the set of possible fault models is finite and known, in which case we employ a multiple model adaptive estimation (MMAE) approach based on a likelihood-ratio (LR) statistic. Unknown system parameters are estimated by an adaptive expectation- maximization (EM) algorithm. Particle filtering techniques are used to reduce the computational complexity in the case of systems with large state-spaces. The efficacy of the proposed methodology is demonstrated by numerical experiments with a large gene regulatory network (GRN) with stuck-at faults observed through a single noisy time series of RNA-seq gene expression measurements. 

   more » « less
3. Constant Coefficient Multipliers Using Self-Similarity-Based Hybrid Binary-Unary Computing

   https://doi.org/10.1109/ICCAD57390.2023.10323844  

   Khataei, Alireza; Bazargan, Kia (October 2023, 2023 IEEE/ACM International Conference on Computer Aided Design (ICCAD))

   Constant coefficient multipliers are widely used in digital signal processing and machine learning architectures. Researchers have proposed HBU-CCM (hybrid binary-unary constant coefficient multiplier), which is an approximate method that outperforms conventional binary and FloPoCo-KCM (table-based real multiplier) methods in terms of hardware cost at the expense of accuracy due to aliasing issues. SimBU (self-similarity-based hybrid binary-unary) is another method that was recently proposed to implement general nonlinear functions using self-similarities leading to few hardware resources. In this work, we use a simplified version of the SimBU algorithm to address the aliasing issues of HBU-CCM and improve accuracy. We also implement a convolution kernel for a Gaussian blurring filter to evaluate our method and compare it to previous works. Our method outperforms conventional binary and FloPoCo-KCM methods in terms of hardware cost with desired accuracy and with no aliasing error as opposed to HBU-CCM. 

   more » « less
4. Small-Signal Modeling and Damping Design of Unfolding-Based Single Stage AC-DC Converter Using the Extra Element Theorem

   https://doi.org/10.1109/APEC48143.2025.10977164  

   Goodrich, Dakota; Zade, Aditya; Gurudiwan, Shubhangi; Mansour, Mahmoud; Zane, Regan; Wang, Hongjie (March 2025, IEEE)

   Unfolder-based quasi-single-stage ac-dc power converter has been widely used for high-power electric vehicle (EV) charging systems for its high efficiency and power density. However, the resonance between the grid inductance (impedance) and the capacitors on the soft-dc-link of the converter impacts the system stability and significantly limits the system control bandwidth and dynamic response performance. A quasi-single-stage ac-dc converter with unfolder plus T-bridge series resonant converter (T-SRC) is studied in this work. The small-signal modeling and plant transfer function derivation of the T-SRC is presented in this paper. A damping filter design using the extra element theorem (EET) is then proposed to achieve high- bandwidth and stable operation of the quasi-single-stage ac-dc converter. Simulation and hardware results from an 18 kW module for high-power EV charging are provided to validate the proposed modeling and damping filter design. 

   more » « less
5. Utilizing photonic band gap in triangular silicon carbide structures for efficient quantum nanophotonic hardware

   https://doi.org/10.1038/s41598-023-31362-9  

   Saha, Pranta; Majety, Sridhar; Radulaski, Marina (March 2023, Scientific Reports)

   Abstract Silicon carbide is among the leading quantum information material platforms due to the long spin coherence and single-photon emitting properties of its color center defects. Applications of silicon carbide in quantum networking, computing, and sensing rely on the efficient collection of color center emission into a single optical mode. Recent hardware development in this platform has focused on angle-etching processes that preserve emitter properties and produce triangularly shaped devices. However, little is known about the light propagation in this geometry. We explore the formation of photonic band gap in structures with a triangular cross-section, which can be used as a guiding principle in developing efficient quantum nanophotonic hardware in silicon carbide. Furthermore, we propose applications in three areas: the TE-pass filter, the TM-pass filter, and the highly reflective photonic crystal mirror, which can be utilized for efficient collection and propagating mode selection of light emission. 

   more » « less