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Low-cost chip-scale optoelectronic gyroscopes having a resolution ≤ 10°/h and a good reliability also in harsh environments could have a strong impact on the medium/high performance gyro market, which is currently dominated by well-established bulk optical angular velocity sensors. The R&D activity aiming at the demonstration of those miniaturized sensors is crucial for aerospace/defense industry, and thus it is attracting an increasing research effort and notably funds. In this paper the recent technological advances on the compact optoelectronic gyroscopes with low weight and high energy saving are reviewed. Attention is paid to both the so-called gyroscope-on-a-chip, which is a novel sensor, at the infantile stage, whose optical components are monolithically integrated on a single indium phosphide chip, and to a new ultra-high Q ring resonator for gyro applications with a configuration including a 1D photonic crystal in the resonant path. The emerging field of the gyros based on passive ring cavities, which have already shown performance comparable with that of optical fiber gyros, is also discussed.

In this paper we study a multi-ring resonant structure including three evanescently coupled ring resonators (named triple ring resonator, TRR), with different ring radii and coupling coefficients, and coupled to two bus waveguides. The potential application of a TRR as a rotation sensor is analyzed and its advantages over a single ring resonator (SRR) under rotation conditions are also highlighted. When the coupled rings have different size and their inter-ring coupling coefficients are lower than the ring-bus coupling coefficients, the resonance frequency difference between two counter-propagating beams induced by rotation is enhanced with respect to that of a single ring resonator (SRR) with the same footprint. The scale factor of the rotating TRR, which depends on the structural parameters (i.e. inter-ring and ring-bus coupling coefficients, lengths of the rings, overall propagation loss within the rings), is up to 1.88 times the value of the scale factor of a SRR, which depends only on the ring radius, by assuming that the waveguide structure in both configurations is the same. This promising numerical achievement results in a reduction of the sensor footprint of about two times, with respect to a single ring with the same scale factor. The results obtained may be useful to define new configurations of frequency sensitive optical gyros in low-loss technology, having a small volume. In fact, by properly choosing the structural parameters, the spectral response of the TRR is forced to assume a shape more sensitive to the resonant frequency shift due to the rotation with respect to that one of a SRR.

The design of a new graphene-based continuously tunable optical delay line formed by two vertically stacked microring resonators coupled to a straight waveguide is proposed. High values of delay time (\taug=360\ \mbox{ps}) and a wide tuning range (\mathit\Delta\taug=230\ \mbox{ps} ) have been calculated, due to the graphene sandwiched between the stacked ring resonators, which also provides an electrooptical tuning of the delay with low energy consumption (E\mathrm{switch}=3.4\ \mbox{pJ}) and fast switching time (t\mathrm{switch}\ <\ 2\ \mbox{ns}). The ratio \mathit\Delta\taug /A represents an important figure of merit (FOM) for optical delay lines. A value \mboxFOM=1.4\times 10^-1\ \mboxps/\mu\mboxm^2 has been calculated, which corresponds to an enhancement of about a factor 4 compared with the state-of-the-art of the integrated optical delay lines, also providing a switching time several times faster. Such performance, together with a small device footprint (<\ 1.6\times 10^3\ \mu\mboxm^2 ) , gives a significant contribution to the state-of-the-art of optical delay lines, confirming the suitability of the graphene-based resonant cavity as a high-efficient optical delay line for applications in which fast tuning and wide range of tunability are required, e.g., phased array antennas. [ABSTRACT FROM PUBLISHER]

A novel photonic/plasmonic cavity based on a 1-D photonic crystal cavity vertically coupled to a plasmonic gold structure is reported. The design has been optimized to achieve an ultra-high Q/V ratio, therefore improving the light-matter interaction and making the device suitable for optical trapping applications. Accurate 3-D finite element method (FEM) simulations have been carried out to evaluate the device behavior and performance. The device shows Q = 2.8 × 103 and V = 4 × 10-4(λ/n), which correspond to a Q/V = 7 × 106(λ/n)-3 with a resonance transmission around 50% at λR = 1589:62 nm. A strong gradient of the optical energy has been observed in the metal structure at the resonance, inducing a strong optical force and allowing a single particle trapping with a diameter less than 100 nm. The device turns out very useful for novel biomedical applications, such as proteomics and oncology. [ABSTRACT FROM AUTHOR]

Abstract: In this work we have investigated different silicon-on-insulator (SOI) microcavities based on a planar geometry having a footprint on chip as small as 100μm2 with a ring, disk and hybrid configurations with the aim of being poorly intrusive for both in-body and out-of-body biosensing purposes. Accurate numerical results have been achieved by using the 3D finite element method and compared to 3D finite discrete time domain ones with a good agreement for both methods. The most promising resonator among the devices we have analyzed shows a Q-factor of the order of 105, that allows a limit of detection for the sensor equal to 10−6 RIU and a sensor sensitivity of 120nm/RIU. The resonator has been designed for glucose biosensing, considering both the homogeneous sensing and the surface one, that enhances the sensor selectivity by the device functionalization with a glucose-oxidase (GOD) layer. The glucose concentration has been evaluated both with the microcavity surrounded by a water solution and with water only in the inner part of the cavity. The achieved performance is really attractive not only for the reduced size of the cavity, but also for the planar coupling configuration of the annulus and the waveguides composing the cavity since it appears to be a very promising configuration for the practical packaging of micro systems containing whispering gallery mode resonators. In this paper the concept of an on-chip platform for a high throughput and multichannel detection relying on an array of resonant cavities interacting with a single nanofluidic channel, is also discussed. [Copyright &y& Elsevier]

In this paper, a very accurate model of optical modulators in silicon-on-insulator technology is developed and validated using experimental results reported in literature. Using an optimized nanometer MOS structure, a significant bandwidth increase (around 45%), length decrease (around four times), and power consumption reduction (three times) with respect to the state-of-the-art have been obtained. [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, we review the different configurations proposed for electromagnetic field optical sensing. Intrinsic and extrinsic optical fiber sensors for electric and magnetic field measurement are examined, including those realized jacketing the fiber by magnetostrictive, conductive, electrochromic and polymeric materials and those measuring induced strain by magnetostrictive, electrostrictive and piezoelectric transducers. Extrinsic optical fiber sensors exploiting magneto-optic, electro-optic and Joule effects are also presented. Moreover, integrated optical electric and magnetic field sensors in which microwave signal provided by an antenna modulates the optical signal generated by an optical source are reviewed. Finally, active and coupled resonators based on electric field sensors are investigated. [Copyright &y& Elsevier]

This book analyses the link the establishment of European citizenship creates between citizenship, nationality and immigration policies. At the national level, European citizenship reinforces the link between citizenship and nationality and at the European level it creates a new link between citizenship practices and immigration policies. This book investigates the degree to which European citizenship encourages the development of a European identity. It compares the impact of European citizenship at the nation-state level in Italy and the UK and their national policies to immigration and citizenship. The author investigates social realities through the empirical analysis of public attitudes towards the EU, European citizenship and immigration by examining changes in law in Italy and the UK. The author concludes that the connection between normative undertakings, based on the establishment of European citizenship to forge a European identity, and social reality are weak. Opinion polls reveal that the establishment of a European citizenship has reinforced the ideology of nationality in both Italy and the UK and failed to forge a European identity. [ABSTRACT FROM AUTHOR]