One of the most intriguing protein materials found in nature is bone, a material composed of assemblies of tropocollagen molecules and tiny hydroxyapatite mineral crystals that form an extremely tough, yet lightweight, adaptive and multifunctional material. Bone has evolved to provide structural support to organisms, and therefore its mechanical properties are of great physiological relevance. In this article, we review the structure and properties of bone, focusing on mechanical deformation and fracture behavior from the perspective of the multidimensional hierarchical nature of its structure. In fact, bone derives its resistance to fracture with a multitude of deformation and toughening mechanisms at many size scales ranging from the nanoscale structure of its protein molecules to the macroscopic physiological scale.

On the Mechanistic Origins of Toughness in Bone

Fiber ring interferometer

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.

https://www.jeos.org/index.php/jeos_rp/article/download/14013/1170

Recent advances in miniaturized optical gyroscopes

We show that a certain fundamental limit applies to the accuracy of all optical rotation sensors which use laser light as a probe. We derive this fundamental rotation-rate uncertainty from the Heisenberg uncertainty relations and Glauber's minimum uncertainty states. The same relationship is obtained from a spontaneous-emission noise formulation. We present experimental data on a (nondithered) four-frequency ring laser gyroscope for which this limit is attained.

Laser gyro at quantum limit

Role of interfacial transition zone in phase field modeling of fracture in layered heterogeneous structures

Resistive switching behavior of TiO2/(PVP:MoS2) nanocomposite hybrid bilayer in rigid and flexible RRAM devices

This paper explains the importance of the role played by photon lifetime in the generation of terminal voltage across Semiconductor Ring Laser Gyroscope (SRLG). This terminal voltage can be used for direct measurement of rotation rate.

Rotation Sensing Through Semiconductor Ring Laser Gyro : Analyzed and Explained Using Photon Lifetime

A novel method of lock-in elimination using electro-optic phase modulator in semiconductor ring laser gyroscope is proposed. It helps in operating the gyro out of the lock-in band, thus improving its sensitivity.

Semiconductor ring laser gyroscope with improved rotation sensitivity

An incoherent beam combination of lower order Laguerre–Gaussian beams is analytically modeled and analyzed in the presence of atmospheric turbulence. For purpose of analysis, 44 individual laser elements are considered and intensity profile of the combined beam is analyzed at regular distances from the source. The resultant intensity is then compared with the similarly combined Gaussian beams. It is found that while combined intensity of LG 10 mode is greater than that of Gaussian for lower propagation distance, it becomes less than Gaussian for distances greater than 3 km from the source. LG 01 mode, on the other hand, shows considerably higher combined intensity as compared to Gaussian even at a distance of 10 km from the source, thus making them a viable prospect for high power directed energy systems.

Incoherent beam combination of low order Laguerre–Gaussian beams propagating in turbulent atmosphere

Ring resonator based biosensor is designed for cancer and hemoglobin detection and structure is optimized for better sensitivity and Q factor. The sensor has the capacity to detect various cancer cells and hemoglobin concentrations with high sensitivity of 200 nm/RIU and a Q factor of around 2000.

Arpit Khandelwal

Papers

Resistive switching behavior of TiO2/(PVP:MoS2) nanocomposite hybrid bilayer in rigid and flexible RRAM devices

Rotation Sensing Through Semiconductor Ring Laser Gyro : Analyzed and Explained Using Photon Lifetime

Semiconductor ring laser gyroscope with improved rotation sensitivity

Incoherent beam combination of low order Laguerre–Gaussian beams propagating in turbulent atmosphere

Optimization of Sensitivity and Q-Factor of Ring Resonator Based Label Free Biosensor