Fiber ring interferometer

Fibre Bragg grating (FBG) strain sensors are not only a very well-established research field, but they are also acquiring a bigger market share due to their sensitivity and low costs In this paper we review FBG strain sensors with high focus on the underlying physical principles, the interrogation, and the read-out techniques Particular emphasis is given to recent advances in highly-performing, single head FBG, a category FBG strain sensors belong to Different sensing schemes are described, including FBG strain sensors based on mode splitting Their operation principle and performance are reported and compared with the conventional architectures In conclusion, some advanced applications and key sectors the global fibre-optic strain sensors market are envisaged, as well as the main market players acting in this field

Fibre Bragg Grating Based Strain Sensors: Review of Technology and Applications.

There is an ever-growing demand for measuring respiratory variables during a variety of applications, including monitoring in clinical and occupational settings, and during sporting activities and exercise. Special attention is devoted to the monitoring of respiratory rate because it is a vital sign, which responds to a variety of stressors. There are different methods for measuring respiratory rate, which can be classed as contact-based or contactless. The present paper provides an overview of the currently available contact-based methods for measuring respiratory rate. For these methods, the sensing element (or part of the instrument containing it) is attached to the subject’s body. Methods based upon the recording of respiratory airflow, sounds, air temperature, air humidity, air components, chest wall movements, and modulation of the cardiac activity are presented. Working principles, metrological characteristics, and applications in the respiratory monitoring field are presented to explore potential development and applicability for each method.

Contact-Based Methods for Measuring Respiratory Rate

This review paper discusses the trends and projections for wearable technology in the consumer sports sector (excluding professional sport). Analyzing the role of wearable technology for different users and why there is such a need for these devices in everyday lives. It shows how different sensors are influential in delivering a variety of readings that are useful in many ways regarding sport attributes. Wearables are increasing in function, and through integrating technology, users are gathering more data about themselves. The amount of wearable technology available is broad, each having its own role to play in different industries. Inertial measuring unit (IMU) and Global Positioning System (GPS) sensors are predominantly present in sport wearables but can be programmed for different needs. In this review, the differences are displayed to show which sensors are compatible and which ones can evolve sensor technology for sport applications.

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Review on Wearable Technology Sensors Used in Consumer Sport Applications

Gyroscopes are essential to many diverse applications associated with navigation, positioning and inertial sensing1. In general, most optical gyroscopes rely on the Sagnac effect—a relativistically induced phase shift that scales linearly with the rotational velocity2,3. In ring laser gyroscopes (RLGs), this shift manifests as a resonance splitting in the emission spectrum, which can be detected as a beat frequency4. The need for ever more precise RLGs has fuelled research activities aimed at boosting the sensitivity of RLGs beyond the limits dictated by geometrical constraints, including attempts to use either dispersive or nonlinear effects5–8. Here we establish and experimentally demonstrate a method using non-Hermitian singularities, or exceptional points, to enhance the Sagnac scale factor9–13. By exploiting the increased rotational sensitivity of RLGs in the vicinity of an exceptional point, we enhance the resonance splitting by up to a factor of 20. Our results pave the way towards the next generation of ultrasensitive and compact RLGs and provide a practical approach for the development of other classes of integrated sensor. A method based on non-Hermitian singularities, or exceptional points, is established and used to increase the Sagnac scale factor and enhance the sensitivity of ring-laser gyroscopes.

Non-Hermitian ring laser gyroscopes with enhanced Sagnac sensitivity.

This paper is an overview of current gyroscopes and their roles based on their applications. The considered gyroscopes include mechanical gyroscopes and optical gyroscopes at macro- and micro-scale. Particularly, gyroscope technologies commercially available, such as Mechanical Gyroscopes, silicon MEMS Gyroscopes, Ring Laser Gyroscopes (RLGs) and Fiber-Optic Gyroscopes (FOGs), are discussed. The main features of these gyroscopes and their technologies are linked to their performance.

Gyroscope Technology and Applications: A Review in the Industrial Perspective

Optical gyroscopes measure the angular velocity using the Sagnac effect. However, the resonance splitting due to the Sagnac effect is directly proportional to the linear dimensions of the device. Consequently, integrated optical gyroscopes are still the subject of research. We propose the idea and the design of an anti-parity-time (APT)-symmetric optical gyroscope exhibiting a resonance splitting independent from the dimensions of the device. With a 80 μm×40 μm footprint integrated device, we demonstrated that it is possible to achieve a resonance splitting 106 times higher than the one obtained through the classical Sagnac effect. With respect to the previously proposed parity-time (PT)-symmetric gyroscope, our solution exhibits a real frequency splitting, directly measurable at the output power spectrum. Moreover, it can be kept at its exceptional point more accurately than the PT-symmetric counterpart. Finally, the anti-PT-symmetric gyroscope presented here can detect the sign of the angular velocity differently from the PT-symmetric one.

High-sensitivity real-splitting anti-PT-symmetric microscale optical gyroscope.

We proposed a new readout scheme for an ultrasensitive gyroscope, which uses the physics of the exceptional points of a PT-symmetric system to enhance the device sensitivity. In particular, we demonstrated that the full-width at half-maximum linewidth (Δ ω FWHM ) of the light exiting the ring resonator system is proportional to the square root of the rotation rate (Ω). Moreover, we designed a PT-symmetric gyroscope, kept at the exceptional point (at rest) with two 100-μm-radius rings, obtaining a theoretical Δ ω FWHM of 3.37×104 rad/s for an angular velocity of 100 °/h. One algorithm capable to keep the system at the exceptional point and another one to identify the direction of rotation are also proposed.

Design Rules of a Microscale PT-Symmetric Optical Gyroscope Using Group IV Platform

Electric vehicles with two motors combined via planetary gear train

Parity-time symmetry has gained attention in optical research, for the interesting properties of exceptional points of showing enhanced sensitivity to external perturbation. Such a property has been widely proposed for different applications. Recently, also anti-parity-time symmetry has gained a growing interest and has been proposed as an alternative to parity-time-symmetric sensors. However, in literature, the effect of the eigenfrequency splitting on the measurable transfer function in the proximity of exceptional point is often neglected, leading to unstable systems and complex readout schemes. In this work it will be shown how parity-time-symmetric and anti-parity-time-symmetric high-sensitivity sensors can be properly designed for refractive index and absorption-based sensing, guaranteeing stability and simplicity of the readout scheme.

Martino De Carlo

Papers

Gyroscope Technology and Applications: A Review in the Industrial Perspective

High-sensitivity real-splitting anti-PT-symmetric microscale optical gyroscope.

Design Rules of a Microscale PT-Symmetric Optical Gyroscope Using Group IV Platform

Electric vehicles with two motors combined via planetary gear train

(INVITED) Exceptional points of parity-time- and anti-parity-time-symmetric devices for refractive index and absorption-based sensing