A novel reconfigurable optical interconnect architecture using an Opto-VLSI processor and a 4-f imaging system

A novel reconfigurable optical interconnect architecture for on-board high-speed data transmission is proposed and experimentally demonstrated. The interconnect architecture is based on the use of an Opto-VLSI processor in conjunction with a 4-f imaging system to achieve reconfigurable chip-to-chip or board-to-board data communications. By reconfiguring the phase hologram of an Opto-VLSI processor, optical data generated by a vertical Cavity Surface Emitting Laser (VCSEL) associated to a chip (or a board) is arbitrarily steered to the photodetector associated to another chip (or another board). Experimental results show that the optical interconnect losses range from 5.8dB to 9.6dB, and that the maximum crosstalk level is below −36dB. The proposed architecture is tested for high-speed data transmission, and measured eye diagrams display good eye opening for data rate of up to 10Gb/s

MobiCacher: Mobility-Aware Content Caching in Small-Cell Networks

Small-cell networks have been proposed to meet the demand of ever growing mobile data traffic. One of the prominent challenges faced by small-cell networks is the lack of sufficient backhaul capacity to connect small-cell base stations (small-BSs) to the core network. We exploit the effective application layer semantics of both spatial and temporal locality to reduce the backhaul traffic. Specifically, small-BSs are equipped with storage facility to cache contents requested by users. As the {\em cache hit ratio} increases, most of the users' requests can be satisfied locally without incurring traffic over the backhaul. To make informed caching decisions, the mobility patterns of users must be carefully considered as users might frequently migrate from one small cell to another. We study the issue of mobility-aware content caching, which is formulated into an optimization problem with the objective to maximize the caching utility. As the problem is NP-complete, we develop a polynomial-time heuristic solution termed {\em MobiCacher} with bounded approximation ratio. We also conduct trace-based simulations to evaluate the performance of {\em MobiCacher}, which show that {\em MobiCacher} yields better caching utility than existing solutions.Comment: Accepted by Globecom 201

An Opto-VLSI-based reconfigurable optical add-drop multiplexer employing an off-axis 4-f imaging system

A novel reconfigurable optical add-drop multiplexer (ROADM) structure is proposed and demonstrated experimentally. The ROADM structure employs two arrayed waveguide gratings (AWGs), an array of optical fiber pairs, an array of 4-f imaging microlenses that are offset in relation to the axis of symmetry of the fiber pairs, and a reconfigurable Opto-VLSI processor that switches various wavelength channels between the fiber pairs to achieve add or drop multiplexing. Experimental results are shown, which demonstrate the principle of add/drop multiplexing with crosstalk of less than -27dB and insertion loss of less than 8dB over the Cband for drop and through operation modes

Optimal limits of cavity optomechanical cooling in the strong coupling regime

Laser cooling of mesoscopic mechanical resonators is of great interest for both fundamental studies and practical applications. We provide a general framework to describe the cavity-assisted backaction cooling in the strong coupling regime. By studying the cooling dynamics, we find that the temporal evolution of mean phonon number oscillates as a function of the optomechanical coupling strength depending on frequency mixing. The further analytical result reveals that the optimal cooling limit is obtained when the system eigenmodes satisfy the frequency matching condition. The reduced instantaneous-state cooling limits with dynamic dissipative cooling approach are also presented. Our study provides a guideline for optimizing the backaction cooling of mesoscopic mechanical resonators in the strong coupling regime.Comment: 8 pages, 6 figure

Tetra­aqua­bis­(N,N-dimethyl­formamide-κO)zinc(II) bis­[(2-{3-[2-(carboxyl­ato­meth­oxy-κ2 O,O′)phen­yl]pyrazol-1-yl-κN 2}acetato-κO)chloridozincate(II)]

The asymmetric unit of the title compound, [Zn(C3H7NO)2(H2O)4][Zn(C13H10N2O5)Cl]2, is composed of a single anion and half a cation. The ZnII atom in the monoanion has a distorted triganol–pyramidal geometry, being coordinated by three O atoms and one N atom from one 2-{3-[2-(carboxyl­ato­meth­oxy)phen­yl]pyrazol-1-yl}acetate ligand and one Cl atom. In the dication, the ZnII atom is located on an inversion center and is coordinated by six O atoms in a slightly distorted octa­hedral geometry. In the crystal, the ions are linked by O—H⋯O hydrogen bonds, forming a two-dimensional network lying parallel to the ab plane. There are also C—H⋯O and C—H⋯Cl inter­actions present, which lead to the formation of a three-dimensional structure