5,127 research outputs found
Ultra-broadband and compact 22 3-dB silicon adiabatic coupler based on supermode-injected adjoint shape optimization
The 22 3-dB couplers are one of the most widely used and important
components in silicon photonics. We propose an ultra-broadband and compact
22 3-dB adiabatic coupler defined by b-splines and optimized with an
efficient supermode-injected adjoint shape optimization. By employing mode
adiabatic evolution and mode coupling at two different wavelength ranges,
respectively, we achieve an ultra-broad bandwidth of 530 nm from 1150nm
to1680nm with a power imbalance below 0.76 dB in a compact coupling length
of 30 according to our simulation results. The supermode-injected
adjoint shape optimization can also be applied to the design of other photonic
devices based on supermode manipulation
A Spiking Neural Network Based Cortex-Like Mechanism and Application to Facial Expression Recognition
In this paper, we present a quantitative, highly structured cortex-simulated model, which can be simply described as feedforward, hierarchical simulation of ventral stream of visual cortex using biologically plausible, computationally convenient spiking neural network system. The motivation comes directly from recent pioneering works on detailed functional decomposition analysis of the feedforward pathway of the ventral stream of visual cortex and developments on artificial spiking neural networks (SNNs). By combining the logical structure of the cortical hierarchy and computing power of the spiking neuron model, a practical framework has been presented. As a proof of principle, we demonstrate our system on several facial expression recognition tasks. The proposed cortical-like feedforward hierarchy framework has the merit of capability of dealing with complicated pattern recognition problems, suggesting that, by combining the cognitive models with modern neurocomputational approaches, the neurosystematic approach to the study of cortex-like mechanism has the potential to extend our knowledge of brain mechanisms underlying the cognitive analysis and to advance theoretical models of how we recognize face or, more specifically, perceive other people’s facial expression in a rich, dynamic, and complex environment, providing a new starting point for improved models of visual cortex-like mechanism
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