Ariel Gomez

Beyond 100-Gb/s Indoor Wide Field-of-View Optical Wireless Communications

Optical fiber communication networks can provide terabit aggregate capacities to buildings and offices within modern cities. Practical wireless systems are orders of magnitude below this capacity. In this letter, we describe an indoor optical bidirectional wireless link with an aggregate capacity over 100 Gb/s. The link operates over ~3 m range at 224 Gb/s (6 x 37.4 Gb/s) and 112 Gb/s (3 x 37.4 Gb/s) with a wide field of view (FOV) of 60° and 36°, respectively. To the best of our knowledge, this is the first demonstration of a wireless link of this type with a FOV that offers practical room-scale coverage.

Simplified impulse response characterization for mode division multiplexed systems

We present a single transceiver based modal characterization method for estimating the channel impulse response of MDM systems. Good agreements are found between the measured and simulated DGDs of a RCF supporting 5 mode groups.

A 50 Gb/s Transparent Indoor Optical Wireless Communications Link With an Integrated Localization and Tracking System

In this paper, we describe an optical wireless communications system that uses light from an optical fibre access point to provide transparent and bi-directional optical links to nomadic terminals. Full localization and tracking is implemented, and a 50 Gb/s link is demonstrated. The link operates in an indoor environment, with a ±30° field-of-view covering a distance of up to 3 m, and a localization accuracy of 0.05° (2.5 mm pointing accuracy at 3 m) is achieved. This demonstration shows that it is feasible to use an automated system to achieve the required alignment for an ultrahigh data rate fibre-wireless-fibre link.

Influence of refractive index profile of ring-core fibres for space division multiplexing systems

Modal properties of step/graded-index ring-core fibres (SI/GI-RCFs) are investigated and compared for application in space-division multiplexing systems.

Mode Coupling Effects in Ring-Core Fibers for Space-Division Multiplexing Systems

An optical fiber with weak mode coupling is desirable for future ultrahigh capacity space-division multiplexing (SDM) systems because mode coupling in an optical fiber results in extrinsic loss of the fiber and crosstalk between guided optical modes. To study the feasibility of a ring-core fiber (RCF) for SDM systems, in this paper, we investigate the mode coupling in the RCF supporting five or seven guided mode groups (MGs) at a wavelength of 1550 nm. For this purpose, the coupled mode/power theory with identified spatial power spectrum of random perturbations of fiber axis is used to estimate the bend loss/crosstalk of the RCF due to microbending. It is shown that based on the identified parameters for the spatial power spectrum in the 5/7-MG RCF, the estimated bend loss/crosstalk of the RCF agrees well with experimental results. In addition, the impact of the gradient parameter α and refractive index contrast Δ of the fiber refractive index profile on bend loss and crosstalk of the RCF is explored. Simulation results indicate that the Δ instead of the α significantly affects bend loss and crosstalk of the RCF. The magnitude improvement in bend loss by increasing the Δ is dependent on the spatial power spectrum.

Design and Demonstration of a 400 Gb/s Indoor Optical Wireless Communications Link

In this paper we report an ultrafast transparent fibre-wireless-fibre link for indoor optical wireless communications. The link operates over ~3 m range at 208 Gb/s with a wide field of view of 40° and 60°, respectively. The system design is fully characterized in simulations, which are in good agreement with the experimental data. To the best of our knowledge, this is the fastest demonstration of an indoor wireless link that offers practical room-scale coverage.

Design of a holographic tracking module for long-range retroreflector free-space systems

Weight reduction and low power consumption are key requirements in the next generation of unmanned aerial vehicles (UAVs). To communicate with an operator, a secured link between the UAV and a ground-based station is desirable. To realize these links, retroreflecting free-space optics is potentially attractive as it offers light weight and low complexity at the UAV. However, the base station requires a high-performance tracking module to enable a steady illumination of the UAV retroreflector. In this paper, we present the design and implementation of a tracking system, which consists of coarse tracking and holographic fine tracking modules working cooperatively. Using this system, experimental field trials were carried out by mounting a multiple-quantum-well-based modulated retroreflector on a commercial UAV. A 2 Mbps optical link was achieved with a bit error rate of ∼2×10-4 at a link range of 300 m.

100 Mb/s wavelength division multiplexing visible light communications link using a triple-junction photo-diode

We report the experimental realization of a 100 Mb/s wavelength division multiplexing link using commercial visible LED sources and a triple-junction photo-diode receiver. This is the first demonstration where multiple-junction technology is used for Visible Light Communication, showing its potential as a compact wavelength-selective transceiver.

A comparative study of optical concentrators for visible light communications

Given the imminent radio frequency spectrum crunch, Visible Light Communication (VLC) is being proposed as an alternative wireless technology allowing for scalable connectivity to potentially millions of mobile and Internet-of- Things (IoT) devices. A VLC system uses a photo-detector (PD) receiver that converts the optically modulated light from a light source into a modulated electrical signal. The corresponding receiver electrical bandwidth is typically inversely proportional to the PD active area. Consequently, to construct a high-speed VLC link, the PD active area is often substantially reduced and an optical concentrator is used to enhance the receiver collection area. However, to achieve high concentrating factor, the link field-of-view (FOV) needs to be narrow due to the étendue conservation in linear passive optical systems. This paper studies a Fluorescent Concentrator (FC) that breaks this étendue conservation. The FC is not only based on reflective and refractive principles but also makes use of fluorescence process. A comparison between the FC and conventional optical concentrators, namely Compound Parabolic Concentrator (CPC) is also investigated. The trade-off between received signal strength and incoming link angle is demonstrated over 60° coverage. Experimental results show that performance degradation as the link angle increases using FC-based receivers is significantly lower than for conventional CPC.