By employing Guigay coefficients, one can describe in an elegant and useful manner the Fresnel diffraction patterns of a periodic structure. Here, we relate Guigay formulation with the classical Fourier series treatment of first order... more
By employing Guigay coefficients, one can describe in an
elegant and useful manner the Fresnel diffraction patterns of a periodic structure. Here, we relate Guigay formulation with the classical Fourier series treatment of first order dispersion. Then, we propose the use of a remarkably simple matrix for describing first order dispersion
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We unveil the use of two grey level masks for controlling continuously the attenuation of a spatial filter, which has an exponentially decreasing hyperbolic profile. We present analytical expressions that help to visualize the influence... more
We unveil the use of two grey level masks for controlling
continuously the attenuation of a spatial filter, which has an
exponentially decreasing hyperbolic profile. We present analytical expressions that help to visualize the influence of our proposed grey level masks for reducing the side-lobes of a 1-D point spread function.
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This editorial contains the overview of the contents of the current issue of Photonics Letters of Poland devoted to optics in Mexico.
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This book is a MUST for everyone in and around the optics community! Fiber Optic Essentials provides professionals and students new to the field of fiber optics with a high-level knowledge of principles, theories and applications. This... more
This book is a MUST for everyone in and around the optics community! Fiber Optic Essentials provides professionals and students new to the field of fiber optics with a high-level knowledge of principles, theories and applications. This primer can also be used as a succinct overview of optics for those with some engineering and physics background.
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The advent of the laser and recent advances in optoelectronics and eJectro-optics have opened up the infrared and visible part of the electromagnetic spectrum for communications and general data-processing applications. Planar... more
The advent of the laser and recent advances in
optoelectronics and eJectro-optics have opened
up the infrared and visible part of the
electromagnetic spectrum for communications
and general data-processing applications. Planar
optical waveguides such as films and strips or
strip-derived structures are needed in these
applications to form distributed components
and to connect components and subsystems.
Glass fibres serve as the transmission medium in
optical communications. This book analyses
light propagation in optical waveguides with a
view to these applications, and treats their
design and fabrication as well as their excitation
by couplers, connectors, and transitions.

It starts with plane-wave absorption,
scattering, and dispersion in the bulk of optical
waveguide materials and their total reflection
at interfaces. Film-guide modes are then derived
from a ray picture and as field solutions,
including graded-index films. Interface scat-
tering and curvature loss are analysed for film
modes, as well as their excitation by grating and
prism couplers, As planar guides with transverse
confinement, film lens guides, strips, strip-
loaded films, and rib and bulge guides are
analysed using a generalized ray concept. Their
excitation by directional couplers follows from
a general theory of coupled waveguides.

Step- and graded-index fibres are first treated
by ray optical methods which are then com-
plemented by more exact field solutions. Thus
guided and leaky mode characteristics are
obtained for multimode and single-mode
operation. The dispersion analysis takes account
of mode, material, and profile dispersion and
arrives at near optimum profiles. For imperfect
fibres, including those with micro-bending, the
solution of coupled wave and coupled power
equations and a power diffusion approximation
allow one to specify fibre tolerances for certain
signal degradations. Methods for fibre fabric-
ation and cabling are presented which produce
optical fibre cables with low loss and distortion.
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Ini contoh dari Proposal PKM-P DIPA UNS 2015. PKM ini mengangkat tema tentang fabrikasi kaca dengan sifat anti air.
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http://adidarwinian.com/photoelectric-effect-particle-nature-of-light/ The concept of wave-particle duality in case of light and other electromagnetic radiation is well-accepted so as to account for the various phenomena exhibited by... more
http://adidarwinian.com/photoelectric-effect-particle-nature-of-light/
The concept of wave-particle duality in case of light and other electromagnetic radiation is well-accepted so as to account for the various phenomena exhibited by light. This paper reviews the phenomenon of photoelectric effect along with the necessary equations in order to demonstrate the particle nature of light. Read full at http://adidarwinian.com/photoelectric-effect-particle-nature-of-light/
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The optical absorption and photoluminescence of anatase and rutile TiO2 were studied at room temperature. TiO2 nanocrystalline powders were synthesized in the form of pure anatase or rutile. The samples were characterized by X-ray... more
The optical absorption and photoluminescence of anatase and rutile TiO2 were studied at room temperature. TiO2 nanocrystalline powders were synthesized in the form of pure anatase or rutile. The samples were characterized by X-ray diffraction, X-ray fluorescence, Raman spectroscopy, optical absorption and photoluminescence (PL) methods. The PL spectra were studied under the intensive UV (3.68eV) laser excitation. Some interesting features in the PL spectra including the well-resolved peaks of excitonic and band–band transitions in TiO2 anatase and rutile were observed, to our knowledge, for the first time. It is shown that PL bands including peaks at 2.71–2.81 eV and its phonon replicas in anatase and rutile TiO2 arise from the excitonic e--h+ recombination via oxygen vacancies. The excitonic peak at 2.91 eV is attributed to the recombination of self-trapped excitons in anatase or free excitons in rutile TiO2. The PL peaks within 3.0–3.3 eV in anatase TiO2 are ascribed to indirect allowed transitions due to the band-band e--h+ recombination. The peaks at 3.03 eV and 3.26 eV are attributed to the free exciton emission near the fundamental band edge of rutile and anatase TiO2, respectively. The influence of TiO2 crystal structure and calcinations temperature on the PL spectra is discussed.
The ability to probe defined neural circuits with both the spatial and temporal resolution imparted by optogenetics has transformed the field of neuroscience. Although much attention has been paid to the advantages of manipulating neural... more
The ability to probe defined neural circuits with both the spatial and temporal resolution imparted by optogenetics has transformed the field of neuroscience. Although much attention has been paid to the advantages of manipulating neural activity at millisecond timescales in order to elicit time-locked neural responses, little consideration has been given to the manipulation of circuit activity at physiologically relevant times of day, across multiple days. Nearly all biological events are governed by the circadian clock and exhibit 24 h rhythms in activity. Indeed, neural circuit activity itself exhibits a daily rhythm with distinct temporal peaks in activity occurring at specific times of the day. Therefore, experimentally probing circuit function within and across physiologically relevant time windows (minutes to hours) in behaving animals is fundamental to understanding the function of any one particular circuit within the intact brain. Furthermore, understanding how circuit function changes with repeated manipulation is important for modeling the circuit-wide disruptions that occur with chronic disease states. Here, we review recent advances in optogenetic technology that allow for chronic, temporally specific, control of circuit activity and provide examples of chronic optogenetic paradigms that have been utilized in the search for the neural circuit basis of behaviors relevant to human neuropsychiatric disease
The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the... more
The ability to probe defined neural circuits in awake, freely-moving animals with cell-type specificity, spatial precision, and high temporal resolution has been a long sought tool for neuroscientists in the systems-level search for the neural circuitry governing complex behavioral states. Optogenetics is a cutting-edge tool that is revolutionizing the field of neuroscience and represents one of the first systematic approaches to enable causal testing regarding the relation between neural signaling events and behavior. By combining optical and genetic approaches, neural signaling can be bi-directionally controlled through expression of light-sensitive ion channels (opsins) in mammalian cells. The current protocol describes delivery of specific wavelengths of light to opsin-expressing cells in deep brain structures of awake, freely-moving rodents for neural circuit modulation. Theoretical principles of light transmission as an experimental consideration are discussed in the context of performing in vivo optogenetic stimulation. The protocol details the design and construction of both simple and complex laser configurations and describes tethering strategies to permit simultaneous stimulation of multiple animals for high-throughput behavioral testing
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