S. Amir Hosseini

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—The acute disparity between increasing bandwidth demand and available spectrum, has brought millimeter wave (mmW) bands to the forefront of candidate solutions for the next-generation cellular networks. Highly directional transmissions are essential for cellular communication in these frequencies to compensate for high isotropic path loss. This reliance on(More)
—The millimeter wave (mmWave) bands have recently attracted considerable interest for next-generation cellular systems due to the massive spectrum at these frequencies. However, a key challenge in designing mmWave cellular systems is initial access – the procedure by which a mobile device establishes an initial link-layer connection to a base station cell.(More)
In this work, we provide a methodology to analyze optimal adaptation policies for scalable video delivery in mobile environments. Typically, download policies for adaptive video are tuned to very specific system settings. The aim of this work is not to propose a new policy, but instead to understand how the optimal policy changes according to the operating(More)
In this article, the authors present and discuss the fabrication of three-dimensional ͑3D͒ optical phased array ͑OPA͒ devices for large angle, two-dimensional optical beam steering. Fabrication of a single layer ͑one-dimensional͒ OPA prototype for one-dimensional beam steering on silicon nanomembrane is presented. The authors present different approaches,(More)
High-rate roll-to-roll (R2R) tracker systems are utilized for large volume flexible electronic device manufacturing, and the current alignment mechanism between layers is mainly achieved by relying on passive techniques. In this paper, we present a machine vision based alignment strategy that is used to achieve precise registration for stacking multilayers.(More)
We investigate the loss mechanism in three-moded multimode-interference couplers that are the building blocks of a compact and low-loss waveguide crossing structure. Broadband silicon waveguide crossing arrays with <0.01  dB insertion loss per crossing are proposed using cascaded multimode-interference couplers, where lateral subwavelength nanostructures(More)
Polymer based electro-optic modulators have shown great potentials in high frequency analog optical links. Existing commercial LiNibO3 Mach-Zehnder modulators have intrinsic drawbacks in linearity to provide high fidelity communication. In this paper, we present the design, fabrication and characterization of a traveling wave directional coupler modulator(More)
The authors would like to acknowledge the Air Force Office of Scientific Research (AFOSR) for supporting this work under the Multidisciplinary University Research Initiative (MURI) program (Grant No. FA 9550-08-1-039), monitored by Dr. Gernot Pomrenke. Abstract: We demonstrate on-chip tunable true-time-delay (TTD) lines based on photonics crystal(More)