Abstract
The performance of a reflective electro-absorption modulator transceiver is assessed in terms of both slope efficiency (SE) and responsivity in a radio-over-fiber network. Different biasing schemes are analyzed, specifically zero bias (passive solution), bias for maximum SE, and bias for maximum responsivity. Finally, two case studies on multiband orthogonal frequency division multiplexing ultra-wide band and Wi-Fi are presented, for which the optimum setup parameters are determined.

Abstract
We report on photo-detectors consisting of an optical waveguide that incorporates a resonant tunneling diode (RTD). Operating at wavelengths around 1.55 m in the optical communications C band we achieve maximum sensitivities of around 0.29 A/W which is dependent on the bias voltage. This is due to the nature of RTD nonlinear current-voltage characteristic that has a negative differential resistance (NDR) region. The resonant tunneling diode photo-detector (RTD-PD) can be operated in either non-oscillating or oscillating regimes depending on the bias voltage quiescent point. The oscillating regime is apparent when the RTD-PD is biased in the NDR region giving rise to electrical gain and microwave self-sustained oscillations Taking advantage of the RTD's NDR distinctive characteristics, we demonstrate efficient detection of gigahertz (GHz) modulated optical carriers and optical control of a RTD GHz oscillator. RTD-PD based devices can have applications in generation and optical control of GHz low-phase noise oscillators, clock recovery systems, and fiber optic enabled radio frequency communication systems.

Abstract
The use of high efficiency resonant coupling wireless power systems for subsea operations is here considered for the charging of autonomous underwater vehicles. In this paper, two architectures based on two different inductors are analysed for their potential as resonant wireless power couplers. Both systems were designed and optimised through electromagnetic 3D simulations, upon which two prototypes were constructed and measured. Efficiencies as high as 75% for distances up to 5 cm were achieved on experimental testing.

Abstract
The present work addresses the design of an electronic system for powering autonomous underwater vehicles (AUVs). We report the study and implementation of a system developed for transmitting and receiving wireless power in water from a docking station to an AUV. A simplified analysis is presented regarding the operation of a class-D power driver in a series-series inductive resonant coupling topology. We further investigate the compromise between link efficiency and power delivery of the system to circumvent the reduced power output capability. Simulation results are provided as well as measurement data validated using circuit prototypes in an experimental setup with a structure similar to the docking station of the AUV filled with salt water.

Abstract
ENDURE and BLUECOM+ are two EEA Grants projects that aim at enabling the monitoring of large and remote ocean areas by providing wireless communications and energy to humans and systems, namely unmanned vehicles, which are crucial for making large scale ocean monitoring cost-effective. ENDURE targets enabling autonomous underwater vehicles (AUVs) to remain in operation for longer periods of time than what is practical today, thus increasing the possibility of covering larger areas at lower costs. BLUECOM+ aims at connecting systems and humans in remote ocean areas by providing cost-effective, broadband, and reliable communications in alternative to satellite communications. Together these projects will bring up the enablers for data collection under the environmental monitoring programme, as well as to the achievement and sustainability of a GES in marine waters. © 2016 Taylor & Francis Group, London.

Abstract
Spatial division multiplexing (SDM) is seen as an effective technique to overcome the present limits of fiber capacity and satisfy future bandwidth requirements, by substantially increasing optical transport capacities [1-5]. Similarly to single-mode fiber based modern telecommunication systems, the nonlinear penalties will eventually become the ultimate limiting factor in SDM systems, arising from crosstalk effects in multimode core or few mode fibers, which generate intramodal and intermodal nonlinearities. Here we explore the concept of conjugated twin waves in few mode fibers based SDM optical systems, as a means to overcome these nonlinear impairments and assess the performance of SDM systems for different PCTW configurations and coupling regimes. Our numerical simulation results show that this technique is an effective means to overcome the nonlinear impairments arising in mode division multiplexed systems, improving performance by up to 10 dB, in the strong coupling regime.