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Topic Review
Plasmons
 We briefly review applications of surface-plasmon polariton modes, related to the design and fabrication of electro–optical circuits.
  • 9.0K
  • 30 Oct 2020
Topic Review
Optical Phase Shifters
Optical phase shifters have the functionality to control the phase of light by a change in the effective refractive index. In a Si photonics platform, it is an essential part composing optical modulators as well as switches in Si photonics. The realization of a silicon optical phase shifter marked a cornerstone for the development of silicon photonics, and it is expected that optical interconnects based on the technology relax the explosive datacom growth in data centers. High-performance silicon optical modulators and switches, integrated into a chip, play a very important role in optical transceivers, encoding electrical signals onto the light at high speed and routing the optical signals, respectively. The development of the devices is continuously required to meet the ever-increasing data traffic at higher performance and lower cost.
  • 7.3K
  • 08 Jun 2021
Topic Review
Laser Absorption Spectroscopy
Laser absorption spectroscopy (LAS) is an absorption spectroscopic method that employs a laser as the light source and measures the chemical concentration based on detection of a variation of laser beam intensity after transmission along the optical path. 
  • 6.1K
  • 10 Sep 2020
Topic Review
Principles of SERS
SERS (Surface-enhanced Raman spectroscopy) is based on the amplification of the Raman response of an analyte interacting with the surface plasmon of metals such as Au, Ag, or Cu; in some cases, the response results enough to achieve the single–molecule detection
  • 5.6K
  • 21 Apr 2021
Topic Review
Intraretinal Fluid Pattern Characterization
The accumulation of fluids in the retinal layers is one of the main causes of blindness in developed countries. The main strategy for its study and diagnosis is through the use of Optical Coherence Tomography (OCT) images. This allows experts to observe the layers of the retina in a cross-sectional view. Commonly, for the analysis of these accumulations by means of computer diagnostic support systems, precise segmentation strategies are employed.
  • 3.0K
  • 22 Apr 2021
Topic Review
Compositional Engineering of Perovskites
We give a systematic overview of compositional engineering by distinguishing the different defect-reducing mechanisms. Doping effects are divided into influences on: (1) crystallization; (2) lattice properties. Incorporation of dopant influences the lattice properties by: (a) lattice strain relaxation; (b) chemical bonding enhancement; (c) band gap tuning. The intrinsic lattice strain in undoped perovskite was shown to induce vacancy formation. The incorporation of smaller ions, such as Cl, F and Cd, increases the energy for vacancy formation. Zn doping is reported to induce strain relaxation but also to enhance the chemical bonding. The combination of computational studies using (DFT) calculations quantifying and qualifying the defect-reducing propensities of different dopants with experimental studies is essential for a deeper understanding and unraveling insights, such as the dynamics of iodine vacancies and the photochemistry of the iodine interstitials, and can eventually lead to a more rational approach in the search for optimal photovoltaic materials.
  • 2.8K
  • 28 Oct 2020
Topic Review
Gabor-Domain Optical Coherence Microscopy
Gabor-domain optical coherence microscopy (GDOCM) is a high transverse resolution variant of spectral domain optical coherence tomography (SD-OCT). It was proposed to break the cellular resolution limit of optical coherence tomography (OCT). GDOCM achieves invariant transverse and axial resolutions of 2 micron in 3D by fusing together multiple volumetric images that are acquired employing a liquid lens to dynamically refocus at different depths inside the sample with no moving parts.
  • 2.7K
  • 29 Oct 2020
Topic Review
Plasmonics in Wireless THz Nanocommunications
Wireless data traffic has experienced an unprecedented boost in the past years, and according to data traffic forecasts, within a decade, it is expected to compete sufficiently with wired broadband infrastructure. It is therefore required the use of even higher carrier frequency bands in the THz range, via adoption of new technologies to equip future THz band wireless communication systems at the nanoscale, in order to accommodate a variety of applications, that would satisfy the ever increasing user demands of higher data rates. Certain wireless applications such as 5G and beyond communications, Network on Chip system architectures, and Nanosensor networks, will no longer satisfy their speed and latency demands with existing technologies and system architectures. Apart from conventional CMOS technology, and the already tested, still promising though, photonic technology, other technologies and materials such as plasmonics with graphene respectively, may offer a viable infrastructure solution on existing THz technology challenges. This survey paper is a thorough investigation on current and beyond state of the art plasmonic system implementation for THz communications, by providing an in-depth reference material, highlighting the fundamental aspects of plasmonic technology roles in future THz band wireless communication and THz wireless applications, that will define future demands coping with users’ needs.
  • 2.6K
  • 30 Oct 2020
Topic Review
Modulators in Silicon Photonics
Silicon optical technology extends beyond just lasers, offering photonic components such as, modulators, photodetectors (PDs), splitters, (de)multiplexers, and filters.
  • 2.6K
  • 08 Feb 2022
Topic Review
Rainbows in Culture
The rainbow, a natural phenomenon noted for its design and its place in the sky, has been a favorite component of art and religion throughout history.
  • 2.6K
  • 14 Oct 2022
Topic Review
Polarization Holography
Polarization holography has the unique capacity to record and retrieve the amplitude, phase, and polarization of light simultaneously in a polarization-sensitive recording material and has attracted widespread attention. Polarization holography is a noteworthy technology with potential applications in the fields of high-capacity data storage, polarization-controlled optical elements, and other related fields.
  • 2.3K
  • 23 Jan 2021
Topic Review
Autostereoscopic Displays Based on Various Display Technologies
The autostereoscopic display is a promising way towards three-dimensional-display technology since it allows humans to perceive stereoscopic images with naked eyes. However, it faces great challenges from low resolution, narrow viewing angle, ghost images, eye strain, and fatigue. Nowadays, the prevalent liquid crystal display (LCD), the organic light-emitting diode (OLED), and the emerging micro light-emitting diode (Micro-LED) offer more powerful tools to tackle these challenges. 
  • 2.2K
  • 21 Feb 2022
Topic Review
Laser-Induced Breakdown Spectroscopy
Laser-Induced Breakdown Spectroscopy (LIBS) has been firstly introduced and proposed for analytical applications almost immediately after the invention of the laser in 1960. Since then, it has been proposed and today is widely used as an alternative analytical method for numerous applications. The operating principle of LIBS is quite simple and is based on the interaction of a powerful enough laser beam, focused usually on or in a sample, inducing a dielectric breakdown of the material, thus resulting in plasma formation consisting of excited and non-excited atoms and molecules, fragments of molecular species, electrons and ions, and emitting characteristic radiations, whose spectroscopic analysis can in principle provide the elemental composition fingerprint of the material. The required instrumentation consisting basically of a laser source, and a spectrometer/monochromator equipped with the appropriate light detector (nowadays being almost exclusively some CCD or ICCD type detector) is relatively simple and economically affordable, while significant progresses have been achieved to small size and/or portable equipment, facilitating largely the in situ operation.
  • 2.1K
  • 31 Aug 2021
Topic Review
Kaleidoscope
A kaleidoscope (/kəˈlaɪdəskoʊp/) is an optical instrument with two or more reflecting surfaces (or mirrors) tilted to each other at an angle, so that one or more (parts of) objects on one end of the mirrors are seen as a regular symmetrical pattern when viewed from the other end, due to repeated reflection. The reflectors are usually enclosed in a tube, often containing on one end a cell with loose, colored pieces of glass or other transparent (and/or opaque) materials to be reflected into the viewed pattern. Rotation of the cell causes motion of the materials, resulting in an ever-changing view being presented.
  • 2.0K
  • 04 Nov 2022
Topic Review
Optical Tweezers
Optical tweezers is a very well-established technique that has developed into a standard tool for trapping and manipulating micron and submicron particles with great success in the last decades. Under tight focusing of a laser beam the optical forces that appear around the focus spot can be both repulsive (scattering force) and attractive (gradient force) towards a particle with higher refractive index than its surroundings. By proper control of these two forces a stable potential can be achieved where a particle can be trapped and manipulated in space. The ability to manipulate micro- and nanoscale matter according to our needs has opened great avenues to a variety of research areas.
  • 2.0K
  • 19 Aug 2020
Topic Review
OES for Atmospheric Plasma Jets
A suitable technique for localized surface treatment of solid materials is an atmospheric pressure plasma jet (APPJ). The properties of the APPJ plasma often depend on small details like the concentration of gaseous impurities what influences the surface kinetics. The simplest and often most useful configuration of the APPJ is presented, characterized by optical emission spectroscopy (OES), and results are discussed in view of various papers. 
  • 1.8K
  • 31 Mar 2021
Topic Review
Optical Coherence Angiography Imaging in Ocular Vascular Diseases
Optical coherence tomography angiography (OCTA) provides us with a non-invasive and efficient means of imaging anterior and posterior segment vasculature in the eye. OCTA has been shown to be effective in imaging diseases such as diabetic retinopathy, retinal vein occlusions, retinal artery occlusions, ocular ischemic syndrome and neovascularization of the iris. It is especially useful with depth-resolved imaging of the superficial, intermediate, and deep capillary plexi in the retina, which enables us to study and closely monitor disease progression and response to treatment. With further advances in technology, OCTA has the potential to become a more widely used tool in the clinical setting and may even supersede ocular angiography in some areas.
  • 1.6K
  • 29 Oct 2020
Topic Review
Plasmonic Biosensors
Biosensors have globally been considered as biomedical diagnostic tools required in abundant areas including the development of diseases, detection of viruses, diagnosing ecological pollution, food monitoring, and a wide range of other diagnostic and therapeutic biomedical research. Recently, the broadly emerging and promising technique of plasmonic resonance has proven to provide label-free and highly sensitive real-time analysis when used in biosensing applications.
  • 1.6K
  • 26 Apr 2022
Topic Review
Mid-infrared Ultrashort Pulse
Mid-infrared (MIR) ultrashort laser pulses, with wavebands ranging from 2 to 20 µm, have a wide range of applications in the fields of environmental monitoring, laser medicine, food quality control, strong-field physics, attosecond science, and some other aspects. There are various technologies for MIR ultrashort pulse generation towards different wavebands.
  • 1.6K
  • 01 Jun 2022
Topic Review
Solution-Processed Organic Phototransistors and Their Recent Developments
Today, more disciplines are intercepting each other, giving rise to “cross-disciplinary” research. Technological advancements in material science and device structure and production have paved the way towards development of new classes of multi-purpose sensory devices. Organic phototransistors (OPTs) are photo-activated sensors based on organic field-effect transistors that convert incident light signals into electrical signals. The organic semiconductor (OSC) layer and three-electrode structure of an OPT offer great advantages for light detection compared to conventional photodetectors and photodiodes, due to their signal amplification and noise reduction characteristics. Solution processing of the active layer enables mass production of OPT devices at significantly reduced cost. The chemical structure of OSCs can be modified accordingly to fulfil detection at various wavelengths for different purposes. Organic phototransistors have attracted substantial interest in a variety of fields, namely biomedical, medical diagnostics, healthcare, energy, security, and environmental monitoring. Lightweight and mechanically flexible and wearable OPTs are suitable alternatives not only at clinical levels but also for point-of-care and home-assisted usage.
  • 1.5K
  • 27 Jan 2022
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