Author
Hui Deng
Bio: Hui Deng is an academic researcher from University of Michigan. The author has contributed to research in topics: Neuromorphic engineering. The author has an hindex of 1, co-authored 1 publications receiving 10 citations.
Topics: Neuromorphic engineering
Papers
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21 May 1990
TL;DR: Results show evidence of ``SpE inhibition'' and ``enhancement,'' of nonexponential decay of SpE signals, and of competition with superradiance and stimulated emission, in all computer calculations of the optical parameters of the multilayered structures used for cavity confinement.
Abstract: The quantum theory of the spontaneous emission (SpE) in the optical microscopic cavity (microcavity) is reported we believe for the first time.1,2 The forms of the modes propagating orthogonally to the mirrors and previously studied by Ley and Loudon3 are here generalized to cover all spatial directions. Microcavity field quantization leads to the expressions of the SpE probabilities Γ||, Γ⊥ for dipoles parallel and orthogonal to the mirrors, respectively. These are computer calculated for some experimentally significant cases involving both metal and dielectric multilayer-mirror coatings.
160 citations
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TL;DR: By strategically interfacing non-Hermitian and topological physics, this approach provides a route to controlling topologically protected light paths in an integrated optical platform and demonstrates arbitrary, robust light steering in reconfigurable non- hermitian junctions.
Abstract: By strategically interfacing non-Hermitian and topological physics, we demonstrate arbitrary, robust light steering in reconfigurable non-Hermitian junctions, in which chiral topological states can propagate at an interface of the gain and loss domains.
74 citations
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TL;DR: In this paper, an electro-absorption modulator based on an IndiumTin Oxide layer, whose dynamic range is used as nonlinear activation function of a photonic neuron, is presented.
Abstract: Recently integrated optics has become an intriguing platform for implementing machine learning algorithms and inparticular neural networks. Integrated photonic circuits can straightforwardly perform vector-matrix multiplicationswith high efficiency and low power consumption by using weighting mechanism through linear optics. Although,this can not be said for the activation function which requires either nonlinear optics or an electro-optic module withan appropriate dynamic range. Even though all-optical nonlinear optics is potentially faster, its current integrationis challenging and is rather inefficient. Here we demonstrate an electro-absorption modulator based on an IndiumTin Oxide layer, whose dynamic range is used as nonlinear activation function of a photonic neuron. The nonlinearactivation mechanism is based on a photodiode, which integrates the weighed products, and whose photovoltage drivesthe elecro-absorption modulator. The synapse and neuron circuit is then constructed to execute a 200-node MNISTclassification neural network used for benchmarking the nonlinear activation function and compared with an equivalentelectronic module.
70 citations
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TL;DR: In this article, the role of the Purcell effect in the stimulated and spontaneous emission rates of semiconductor laser is investigated, taking into account the carriers' spatial distribution in the volume of the active region over a wide range of cavity dimensions and emitter/cavity linewidths, enabling the detailed modeling of the static and dynamic characteristics of either micro- or nano-scale lasers using singlemode rate-equations analysis.
Abstract: Nanoscale semiconductor lasers have been developed recently using either metal, metallo-dielectric or photonic crystal nanocavities. While the technology of nanolasers is steadily being deployed, their expected performance for on-chip optical interconnects is still largely unknown due to a limited understanding of some of their key features. Specifically, as the cavity size is reduced with respect to the emission wavelength, the stimulated and the spontaneous emission rates are modified, which is known as the Purcell effect in the context of cavity quantum electrodynamics. This effect is expected to have a major impact in the 'threshold-less' behavior of nanolasers and in their modulation speed, but its role is poorly understood in practical laser structures, characterized by significant homogeneous and inhomogeneous broadening and by a complex spatial distribution of the active material and cavity field. In this work, we investigate the role of Purcell effect in the stimulated and spontaneous emission rates of semiconductor lasers taking into account the carriers' spatial distribution in the volume of the active region over a wide range of cavity dimensions and emitter/cavity linewidths, enabling the detailed modeling of the static and dynamic characteristics of either micro- or nano-scale lasers using single-mode rate-equations analysis. The ultimate limits of scaling down these nanoscale light sources in terms of Purcell enhancement and modulation speed are also discussed showing that the ultrafast modulation properties predicted in nanolasers are a direct consequence of the enhancement of the stimulated emission rate via reduction of the mode volume.
12 citations