Publisher Summary A refractive index can be increased by ion implantation by changes in density and structure, by the addition of high-polarizability impurity ions, by a reduction of the plasma effect that increases the index and that is most important in the wavelength region far from the energy gap, and by absorption changing in the index in the region of the gap, that is, via the Kramers–Kronig relation. This chapter discusses the optical properties of implanted semiconductors, electrooptic components formed by ion implantation, general principles that determine most luminescent systems, effects of implantation temperature, luminescence centers in LiF-Mg-Ti radiation dosimeters, and use of line spectra in defect studies. In the LiF system, the luminescence bands are broad, and if alternative versions of the same complex exist, they cannot be resolved from the spectra. The addition, by implantation, of ions with incomplete inner electron shells opens up new possibilities as the lattice distortions of the free-ion energy levels are strongly perturbed by the defects in the neighborhood of the ion.

Optical Effects of Ion Implantation

Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications.

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Gait analysis using wearable sensors.

Metaheuristic design of feedforward neural networks

Development of ion-implanted optical waveguides in optical materials: A review

Ion implantation is a powerful technique for surface analysis and material modification and this review discusses the effects that specifically relate to optical properties of insulators. By selection of ion energy and ion dose one can inject trace impurities that control luminescence, generate optical absorption bands or complex defect aggregates, stimulate production of new crystalline phases or destroy crystallinity. Implantation invariably stimulates luminescence which provides a sensitive means of analysis to measure purity and near-surface defect concentrations. Post-implantation measurements reveal changes in many physical and chemical properties of the materials. Some, such as chemical reactivity, can increase a thousandfold, others such as birefringence, electro-optic and acoustic wave parameters are reduced. One major property which can be controlled is the refractive index; thus optical waveguides, and ultimately, complex integrated optical devices can be precisely defined by ion implantation.

https://iopscience.iop.org/article/10.1088/0034-4885/50/5/001/pdf

Optical effects of ion implantation

Solving differential equations with constructed neural networks

https://users.cs.uoi.gr/~itsoulos/publications/nnc_neurocomputing.pdf

Neural network construction and training using grammatical evolution

A novel optical fibre sensor has been developed for on-line monitoring of oil quality within industrial equipment. The monitoring is based on chromatic modulation because of the inherent self-referencing demonstrated by this technique. The sensor is shown to exhibit long-term stability and is capable of operating up to a temperature of 120 degrees C. Several industrial oils have been examined using the sensor, and typical modulation depths of 20% were obtained with resolution in the range of 0.1%. This is sufficient to record some interesting physical and chemical changes related to the reaction kinetics of oil degradation. The sensor is also capable of detecting oil leaks within a system since it can distinguish between the chromaticities of oil and air.

https://iopscience.iop.org/article/10.1088/0957-0233/4/5/011/pdf

A fibre-optic oil condition monitor based on chromatic modulation

A comparative study is presented of the optical damage induced by green light in LiNbO3 waveguides prepared by Ti in-diffusion, proton exchange and ion implantation. The methods used were monitoring the out-coupled light power as a function of time and as a function of in-coupled power, and writing and erasing a holographic grating inside the guide. With the first method, the optical damage stability of Ti-diffused guides is greatly inferior to the other two types, optical damage appearing at in-coupled intensities of 6 W cm-2 in Ti-diffused guides but not until 500 W cm-2 in exchanged and implanted guides. With the holographic method, however, a similar photorefractive behaviour is observed for diffused and implanted guides which contain similar levels of Fe2+ impurities, whereas much less damage is apparent in proton-exchanged guides. Main photorefractive parameters are given for the three types of guides and their physical implications briefly discussed.

A comparison of optical damage in different types of LiNbO3 waveguides

Ion implantation forms optical waveguides in both LiNbO3 and LiTaO3 but in order to employ these in device applications one must be able to minimise barrier losses and absorption losses by using multiple energy implants and by annealing colour centres respectively. This requires a knowledge of the refractive index profile behaviour both as a function of dose and as a function of subsequent annealing. The paper reports mode measurements on a variety of waveguides formed by He+ ion implantation with different dose levels, ion energies and implant temperatures, and their subsequent isochronal anneal. Refractive index profiles are deduced using different wavelengths and index orientations, and the growth and recovery curves of the nuclear and electronic regions are compared for the two materials.

E. Glavas

Papers

Solving differential equations with constructed neural networks

Neural network construction and training using grammatical evolution

A fibre-optic oil condition monitor based on chromatic modulation

A comparison of optical damage in different types of LiNbO3 waveguides

Thermal stability of ion implanted LiTaO3 and LiNbO3 optical waveguides