We present a silicon implementation of a 4-port universal linear optical circuit. Instead of predefining the exact functionality of a photonic circuit at design time, we demonstrate a simple generic silicon photonic circuit, combined with electronic control and software feedback, that can perform any linear operation between its 4 input and output ports. The circuit consists of a network of thermally tunable symmetric Mach-Zehnder interferometers with phase and amplitude control, in-circuit optical power monitors, and local software controlled feedback loops. The circuit can be configured using a training mechanism, which makes it to self-adapt to implement the desired function. We use the circuit to demonstrate an adaptive, universal beam coupler, as well as a switch matrix.

Abstract. As optical fibers revolutionize the way data is carried in telecommunications, the same is happening in the world of sensing. Fiber-optic sensors (FOS) rely on the principle of changing the properties of light that propagate in the fiber due to the effect of a specific physical or chemical parameter. We demonstrate the potentialities of this sensing concept to assess pressure in biomedical and biomechanical applications. FOSs are introduced after an overview of conventional sensors that are being used in the field. Pointing out their limitations, particularly as minimally invasive sensors, is also the starting point to argue FOSs are an alternative or a substitution technology. Even so, this technology will be more or less effective depending on the efforts to present more affordable turnkey solutions and peer-reviewed papers reporting in vivo experiments and clinical trials. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

No abstract

A technique for the demodulation of fiber Bragg grating (FBG) sensors based on the use of a second wavelength-matched FBG receiver to track wavelength shifts from the FBG sensor is analyzed, particularly regarding its sensitivity as determined by primary noise sources. Numerical and experimental results show that there is an optimum Bragg wavelength difference between the two FBG's that maximizes the sensitivity for this demodulation technique.

Abstract:The intrinsic advantages of optical sensor technology are very appealing for high voltage applications and can become a valuable asset in a new generation of smart grids. In this paper the authors present a review of optical sensors technologies for electrical current metering in high voltage applications. A brief historical overview is given together with a more detailed focus on recent developments. Technologies addressed include all fiber sensors, bulk magneto-optical sensors, piezoelectric transducers, magnetic force sensors and hybrid sensors. The physical principles and main advantages and disadvantages are discussed. Configurations and strategies to overcome common problems, such as interference from external currents and magnetic fields induced linear birefringence and others are discussed. The state-of-the-art is presented including commercial available systems.