On-chip magnetic-free optical multi-port circulator based on a locally linear parity-time symmetric system.

This paper introduces a new type of magnetic-free optical circulator without utilizing a Faraday rotator, polarization beam splitter, and magneto-optic material for the first time, to the best of our knowledge. The designed circulator operates linearly and relies on the parity-time symmetric (PTS) system. The property of the non-Hermitian system (the linear PTS system) plays the key role in the suggested optical circulator so that it can simultaneously support N-ports. The proposed device is integrated, broadband, and operates in the optical telecommunication frequency band. A great value of isolation rate of 47 dB is achieved. The proposed circulator can pave the way for optical integrated circuits and optical networks.

An Algorithmic Model of Decision Making in the Human Brain.

INTRODUCTION: One of the interesting topics in neuroscience is problem solving and decision-making. In this area, everything gets more complicated when events occur sequentially. One of the practical methods for handling the complexity of brain function is to create an empirical model. Model Predictive Control (MPC) is known as a powerful mathematical-based tool often used in industrial environments. We proposed an MPC and its algorithm as a part of the functionalities of the brain to improve the performance of the decision-making process. METHODS: We used a hybrid methodology whereby combining a powerful nonlinear control system tools and a modular fashion approach in computer science. Our hybrid approach employed the MPC and the Object-Oriented Modeling (OOM) respectively. Therefore, we could model the interaction between most important regions within the brain to simulate the decision-making process. RESULTS: The employed methodology provided the capability to design an algorithm based on the cognitive functionalities of the PFC and Hippocampus. The developed algorithm applied for modulation of neural circuits between cortex and sub-cortex during a decision making process. CONCLUSION: It is well known that the decision-making process results from communication between the prefrontal cortex (working memory) and hippocampus (long-term memory). However, there are other regions of the brain that play essential roles in making decisions, but their exact mechanisms of action still are unknown. In this study, we modeled those mechanisms with MPC. We showed that MPC controls the stream of data between prefrontal cortex and hippocampus in a closed-loop system to correct actions.