Laser Materials Processings - Photonic devices - Nonlinear optics Research Papers (original) (raw)

Growing need for Anitmonide based , room temperature, 2-5 μm, semiconductor laser, ultra low loss optical communication motivate me to do this work. The work describe in this proposal is aimed to use past investigated result of photoluminescence from GalnSb/AllnSb type first multiple quantum wells grown on GaAs in new way. This investigation successfully found that luminescence lie in between 3-4 μm. In my demonstration I used eight different samples GalnSb/AlGalnSb/AllnSb multiple quantum well laser (In cylindrical VCSEL structure) attached in single 3D photonic crystal emitting mid infrared laser light to transmit binary data from one computer to another computer through chalcogenide optical fibers by using DWDM system.

Laser surface texturing of materials potentially offers precise control of surface structure and mechanical properties. This has a wide range of applications such as control of frictional forces, control of bond strength in interference fit joints, and production of antifouling surfaces. To achieve such texturing in a well-defined, useful manner, precise control of the applied laser processing parameters over a sizeable surface area is required. This paper presents the development of a method for creating highly repeatable and predetermined moiré textured patterns on metallic samples via laser processing. While the method developed is broadly applicable to various materials and laser systems, in the example detailed here the surfaces of cylindrical stainless steel samples were processed with a pulsed CO 2 laser. The resulting modified surfaces contained texture geometries with pre-definable peak-to-peak widths, valley-to-peak heights, and texture directions. The method of achieving this theoretically and experimentally is detailed in this paper. The relationship between the laser processing parameters and resulting diameter increase was confirmed via Design of Experiment response surface methodology. Precise control of the laser textured cylindrical surface outer diameter and texture pattern are key factors in determining the potential suitability of this process for application to the production of interference fit fasteners. The effects of the laser processing parameters and topologies of the resulting re-solidified metal profile on the surfaces were assessed in detail with a focus on this application.

Although the postulate of " photon-having-zero-rest-mass " became over the years a sort of " dogma " , routinely repeated in thousands of physics textbooks and scientific articles, great physicists like two " fathers " of Quantum Mechanics: Erwin Schrödinger and Louis De Broglie, never believed that photons were really " massless " at rest, and many other remarkable physicists challenged this conviction as well. In recent years (2001-2005), the experiments through which Lene Westengarten Hau succeeded in slowing down, stopping, and making restart a laser light pulse by making it pass through optical molasses and ultra-cold sodium vapors of BEC (Bose-Einstein Condensates) can be interpreted as final and persuading evidence that photons –being both particles and e.m. waves-do possess a rest mas and they can be damped in " classical " and quantum ways as damped harmonic oscillators (classical) and superposing waves (QM). Therefore the speed of light is neither an universal constant (c), nor it is " invariant under Lorentz' transformations " , thereby destroying the 2 main pillars of Einstein's SR (Special Relativity). " There must be no barriers to freedom of inquiry. There is no place for dogma in science. The scientist is free, and must be free to ask any question, to doubt any assertion, to seek for any evidence, to correct any errors. " (J. Robert Oppenheimer)

- by Alberto Miatello
- •
- Condensed Matter Physics, Quantum Physics, Quantum Optics, Relativity

Self-cleaning properties have received significant attention for the importance of their potential. Coatings at Nano-scales offer possibilities of using materials for self-cleaning surfaces. Recent efforts have begun to focus on the kinds of materials including metals, semiconductors and polymers. Such materials can have enormous potential in only a few applications. Moreover, the production of these materials requires high costs with low photo activity. In this regard, TiO 2 and its derived materials have shown acceptable and effective suggestions for this application. Moreover, the mechanism of self-cleaning has been explained by the effect of hydrophilic and hydrophobic. Hydrophilic and hydrophobic can have many applications in different areas like water purification, microfluidics and photovoltaic. In this review, the application of self-cleaning in solar cells and environment as well as TiO 2 derived materials and their applications in water management have been briefly illustrated. In addition, it has been explained that a huge number of self-cleaning materials, applications and improvement in utilities have been essential. In short, we have conducted a comprehensive review of the new approach and to mention numerous materials with hydrophobic and hydrophilic properties would be promising for most environmental concerns. Bio-inspired surface respond in nature through hydrophobic (Cicada Wing, Butterfly Wing, Lotus Leaf, Rice Leaf) and hydrophilic (Fish Scale, Snail Shell, Shark Skin) properties was divided in 4 and 3 respectively. Anti reflective coatings with self-cleaning properties have drowned considerable attention for both their basic appearances and vast applied usages. Antireflective coatings with self-cleaning properties have been considered because of their fascinating features and vast diversity of empirical uses.

The use of lasers to weld polymer sheets provides a means of highly-adaptive and custom additive manufacturing for a wide array of industrial, medical, and end user/consumer applications. This paper provides an open source design for a laser polymer welding system, which can be fabricated with low-cost fused filament fabrication and off-the-shelf mechanical and electrical parts. The system is controlled with free and open source software and firmware. The operation of the machine is validated and the performance of the system is quantified for the mechanical properties (peak load) and weld width of linear low density polyethylene (LLDPE) lap welds manufactured with the system as a function of linear energy density. The results provide incident laser power and machine parameters that enable both dual (two layers) and multilayer (three layers while welding only two sheets) polymer welded systems. The application of these parameter sets provides users of the open source laser polymer welder with the fundamental requirements to produce mechanically stable LLDPE multi-layer welded products, such as heat exchangers.

Privacy and secure communication have always been a sensitive topic that became crucial after the digital revolution. Nowadays we can count on asymmetric cryptography protocols whose security relies on a computational hardness assumption, which could be soon invalidated by the rapid progress of computing. This means that our security is seriously threaten. Luckily, information-theoretically secure communication has been shown to be achievable by exploiting the laws of quantum mechanics in the so-called ”quantum key distribution” (QKD), and some proposed protocols have already been proved to be unbreakable. Of course, to implement those protocols into real devices one has to face the imperfections and limits of current technology and here comes a brand new battlefield in the war between hackers and defenders: security loopholes in employed modules. This work aims to investigate suitable hacking strategies that a potential eavesdropper might adopt in order to break optical secure quantum key distribution without being noticed and hence violate secret communications held between legitimate parties. Moreover, our goal is to provide a complete overview of the security of a plug-and- play QKD prototype, located in Padua. Therefore, a research regarding the latest and most dangerous hacking techniques is presented, together with the most promising strategies developed in order to reveal the hacker’s presence and defeat his attacks. Finally, we depict our experimental apparatus and highlight its weaknesses together with suitable attacks. Some possible countermeasures are proposed and weighted in order to select the best feasible defensive system.

- by Alessandro Marcomini
- •
- Quantum Computing, Quantum Optics, Quantum Information, Quantum Mechanics

This article presents a three-layer index guided lead silicate (SF57) photonic crystal fiber which simultaneously promises to
yield large effective optical nonlinear coefficient and low anomalous dispersion that makes it suitable for supercontinuum
(SC) generation. At an operating wavelength 1550 nm, the typical optimized value of anomalous dispersion and effective
nonlinear coefficient turns out to be ~4 ps/km/nm and ~1078 W−1km−1, respectively. Through numerical simulation, it is
realized that the designed fiber promises to exhibit three octave spanning SC from 900 to 7200 nm using 50 fs ‘sech’
optical pulses of 5 kW peak power. Due to the cross-phase modulation and four-wave mixing processes, a long range of
red-shifted dispersive wave generated, which assists to achieve such large broadening. In addition, we have investigated
the compatibility of SC generation with input pulse peak power increment and briefly discussed the impact of nonlinear
processes on SC generation.

- by Mohit Sharma
- •
- Optical Fiber Communications, Fiber Optics, Nonlinear Optics, Photonic Crystals

The generation of Helmholtz-Gauss beam families such as Mathieu-Gauss (MG) and Bessel-Gauss (BG) beams can be dramatically suffered from heat-induced thermal effects. This work is devoted to the generation of MG beams under severe induced thermal loads. The output MG beams of a solid-state laser were assumed to pass through an ABCD system matrix. The simulated results which were achieved by characterization of the transfer matrix of the thermally affected inhomogeneous medium report systematic variations of the intensity profile of MG beams from pump power of 1-5 W. It is shown that for high values of pump power, the thermal effects are so influential and the beam intensity profile is so changed that the identification of MG beams is not easily possible at first hand. The results can facilitate this identification and can be utilized for deeper understanding of thermal effects phenomena.

The in situ synthesis and patterning of CdS nanocrystals in a polymer matrix is performed via multi-photon absorption. Quantum-sized CdS nanocrystals are obtained by irradiating a cadmium thiolate precursor dispersed in a transparent polymer matrix with a focused near infrared femtosecond laser beam. High resolution transmission electron microscopy evidences the formation of nanocrystals with wurtzite crystalline phase. Fluorescent, nanocomposite patterns with sub-micron spatial resolution are fabricated by scanning the laser beam on the polymer–precursor composite. Moreover, the emission energy of the CdS nanocrystals can be tuned in the range 2.5–2.7 eV, by changing the laser fluences in the range 0.10–0.45 J cm−2. This method enables therefore the synthesis of luminescent, CdS-based composites to be used within patterned nanophotonic and light-emitting devices.

- by Andrea Camposeo and +1
- •
- Laser Spectroscopy, Microstructure, Electron Microscopy, Synthesis of nanoparticles

The recent improvements of the commercial, general purpose Finite Element Analysis (FEA) software have allowed them to be used for modeling ablation problems. ABAQUS for example, provides a user-subroutine UMESHMOTION along with the Arbitrary Lagrangian-Eulerian (ALE) adaptive remesh algorithm that enable the users to couple the heat transfer with the progressive surface recession (i.e., ablation). However, such a numerical capability is limited to model ablation problems when the ablation front (i.e., receding surface) is confined within a single material domain (e.g., homogenous material). For ablation problems when the ablation front proceeds from one material domain to another (e.g., laminated composite materials that consist of multiple laminate layers with different material orientations), such a numerical capability is insufficient, since the mesh is not allowed to flow from one material domain to another when the UMESHMOTION subroutine is used. In this paper, a novel computational procedure that sequentially performs the general heat transfer analysis and the general static analysis in ABAQUS, is proposed enabling the capability of ABAQUS for modeling ablation of laminated composites. The proposed procedure is verified by comparing the predictions of temperature and ablation histories of a two-dimensional isotropic panel (i.e., with single material domain) with those obtained using the traditional UMESHMOTION+ALE method. In addition, a case study of applying the proposed procedure to predict the thermal and ablation response of a laminated carbon fiber reinforced epoxy matrix (CFRP) composite panel subjected to a high-intensity and short-duration radiative heat flux is demonstrated.

This thesis presents a range of advances in the fabrication of femtosecond laser textured and hyperdoped silicon, a material platform with potential applications in photovoltaics, photodetectors, light-emitting diodes, lasers, and... more

The Drude-Lorentz model, which makes it possible to describe a nonlinear response of a dielec-tric or conducting medium, can be suited for the description of nonlinear nonresonant responses of some exotic media: topological insulators, a Weil semimetal, or a Dirac metal. A generalized Drude-Lorentz model and its simplified version, in which topological effects are taken into account to a minimum extent, are presented. As an example of application of the simplified model, the second-order nonlinear conductivity is derived, which is responsible for the second harmonic generation and the effect of optical rectification. It is shown that the ratio of the topological conductivity to the ordinary linear conductivity contains constants that are proportional to the fine structure constant and the axion field gradient.

After a brief introduction to the field of light-responsive materials, this paper provides a general theory for mod-eling the photomechanical response of a material, applies it to the two best-known mechanisms of photothermal heating and photoisomerization, and then describes an experimental procedure for quantitative measurements of the stress response. Several different materials are characterized to illustrate how the experiments and theory can be used to isolate the contributing mechanisms through both photomechanical measurements and auxiliary measurements of laser heating and thermal expansion. The efficiency and figure of merit of the photomechanical response are defined on several scales from the molecule to the bulk, and the photomorphon-the basic material element that determines the bulk response-is introduced. The photomorphon provides a conceptual model that can be expressed in terms of viscoelastic elements, such as springs in series and parallel with the photoactive molecule. The photomechanical response, figure of merit, and the deduced microscopic photomechanical properties are tabulated and proposals for new materials classes are made.

- by Zoya Ghorbanishiadeh
- •
- Materials Science, Polymer science, Nonlinear Optics, Liquid Crystals

In the present study, a detailed study of the characterization of laser-surface textured titanium alloy (Ti-6Al-4V) with line and dimple geometry developed by using an ArF excimer laser operating at a wavelength of 193 nm with a pulse length of 5 ns is undertaken. The characterization of the textured surface (both the top surface and cross section) is carried out by scanning electron microscopy, electron back scattered diffraction (EBSD) technique and X-ray diffraction techniques. There is refinement of microstructure along with presence of titanium oxides (rutile, anatase and few Ti 2 O 3 phase) in the textured surface as compared to as-received one. The area fractions of linear texture and dimple texture measured by image analysis software are 45% and 20%, respectively. The wettability is increased after laser texturing. The total surface energy is decreased due to linear (29.6 mN/m) texturing and increased due to dimple (67.6 mN/m) texturing as compared to as-received Ti-6Al-4V (37 mN/m). The effect of polar component is more in influencing the surface energy of textured surface.

Fiber lazerler, üstün pratik özellikleriyle son yıllarda en çok dikkat çeken, en hızlı gelişmelerin yaşandığı ve tarihte laboratuvardan endüstriye geçen en hızlı lazer olarak ön plana çıkmaktadır. Fiber lazerlerde yaşanan gelişmeler yoğun olarak son 15 yıla ait olup, teknolojik gelişmelere paralel olarak
endüstriyel alanlar başta olmak üzere savunma sanayii, medikal ve bilimsel
alanlarda hızla kullanımı yaygınlaşmaktadır.
Bu gelişmedeki en önemli pay, Yb-katkılı çift kaplı (double cladd DC)
fiberler ve yüksek güçlü uyarım diyotlarına (pump diodes) aittir. Fiber lazerlerin diğer lazerlerden daha fazla ön plana çıkmasının ana sebepleri arasında yüksek ışın kalitesi, yüksek alan/hacim oranı, yüksek kazanım ve verimlilik, hassas hizalama gerektirmeyen optik yapı ve soğutma ile ilgili gereklerinin daha kolay olması sayılabilir[1-2]. Yüksek ışın kalitesi sayesinde fiber lazerler birçok uygulama alanında ön plana çıkmaktadır.
Yüksek güçlü CW fiber lazer teknolojisinin gelişmesindeki en önemli faktörlerden biri Yb-katkılı aktif fiberlerdir. Bu elementin aktif katkı maddesi
olarak seçilmesini sağlayan birçok özellik vardır. Kısaca bu özellikler geniş
emisyon aralığı, geniş emilim aralığı, düşük kuantum defect, yarıkararlı ömür
süresinin uzun olması ve yüksek emilim değeridir. Geniş emisyon aralığı tasarım esnekliği açısından kolaylık sağlamaktadır. Yb-katkılı fiberler lazerlerin en iyi çalıştığı emisyon aralığı 1060 nm ile 1100 nm arasındadır ki bu da bize 50 nm bir çalışma alanı vermektedir. Geniş emilim aralığı 900 nm ile 1050 nm bölgesini
kapsamaktadır. Buradaki en büyük avantaj ticari olarak kolaylıkla ulaşılabilen 9xx nm yüksek güçlü lazer diyotların Yb-katkılı fiberlerin emilim bandı ile uyumlu olmasıdır. Ayrıca Yb-katkılı fiberlerin emisyon ve emilim aralıklarının uygun
durumundan dolayı “tandem-pumping” diye adlandırılan özel bir optik uyarım tekniği kullanmak mümkündür. Şu ana kadar ulaşılan en yüksek güçlü fiber lazer (10KW) bu teknik sayesinde geliştrilmiştir. Ayrıca düşük kuantum defect, termal sorunları minimize ettiği için ciddi bir advantaj sağlamaktadır. Yb-katkılı fiberler
için teorik değer %10’dur. Bu özellik termal sorunlara daha kolay çözümler
üretilmesine imkan tanımaktadır. Bunun yanında Yb-elementinin yarıkararlı ömür
FOTONİK 2013 | 15. Ulusal Optik, Elektro-Optik ve Fotonik Çalıştayı 46süresinin uzun olması (yaklaşık 1ms) fiber içine katkı edilecek konsantrasyonun yüksek değerlere çıkmasına izin vermektedir. Single-Clad (tek-kaplı) Yb-katkılı aktif fiberler kullanarak yüksek güçlere
çıkmanın münkün olmamasından dolayı “Cladding-Pumping” tekniği kullanılmıştır. Bu teknik için “double-clad” (DC) fiberler geliştirilmiştir. Double clad fiberlerde dış katmana fazladan bir katman (outer-clad:dış-kap) daha eklenerek multimode (çok-kipli) optik uyarım ışığının inner-clad (iç-kap)
içerisinde ilerlemesi sağlanır. Ayrıca inner-clad içinde ilerleyen uyarım ışığı ile core içinde ilerleyen lazer sinyalinin etkileşimini arttırmak için inner-clad normalden farklı olarak yuvarlak bir geometriye sahip değildir. Sıklıkla kullanılan geometri oktogonaldir. Bu sayede optik çevirim verimliliğinde ciddi artış
sağlanmaktadır. Bu yapı sayesinde çok yüksek uyarım seviyelere çıkmak
mümkün olmaktadır.
Geliştirdiğimiz sürekli dalga (CW) fiber lazer sistemi şekil-1’de
gösterilmiştir. Sisteme yaklaşık 310 W uyarım ışığı sağlayacak 976 nm
dalgaboyunda 14 adet lazer diyot bağlanmıştır. Bu lazer diyotlar “multi-mode coupler” (çok-kipli birleştirici) kullanarak sisteme bağlanmıştır. Lazer rezanatörümüz temelde üç elemandan oluşmaktadır. Bunlar, yüksek seviyeli yansıtıcı fiber bragg grating FBG-1, düşük seviyeli yansıtıcı fiber bragg grating
FBG-2 ve bu iki elemanın ortasına yerleştirilen Yb-katkılı DC fiberden oluşmaktadır. Lazer sistemine toplam 310 W uyarım gücü verilerek 1060 nm dalgaboyunda 0.5 nm bant genişliği olan 200 W sinyal gücü elde edilmiştir. Sistemin uyarım-sinyal çevirim verimliliği yaklaşık %65 seviyesindedir.
Sistemden alınan ölçümlerin grafikleri şekil-2’de verilmektedir.
Bu çalışmada, kendi geliştirmiş olduğumuz sürekli dalga (CW) fiber lazer sisteminden 200 W sinyal gücü elde eilmiştir. Lazer sistemi ile yapılan uzun süreli denemeler sonucunda kararlılık ve güvenirlilik testlerini başarı ile sonuçlanmıştır. Ayrıca bu çalışmada kazanılan bilgi ve tecrübeler kW seviyesinde fiber lazer geliştirmek için ciddi katkılar sağlamış, kW seviyesi hedefi için önemli bir adım olumuştur. Bugün, stratejik ve çekirdek teknoloji olarak kabul edilen bu ürünleri, endüstriyel alanda kullanım için dahi temin etmek belirli taahhüt ve lisanslara bağlıdır. Bu çeşit lazerlerin endüstriyel, bilimsel ve savunma sanayisi uygulamaları gibi geniş alanlarda kullanımı olması,
yapılan bu çalışma ile elde edilen sonuçların önemini daha da ortaya koymaktadır.

Femtosecond laser irradiation followed by chemical etching (F.L.I.C.E.) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels in silica. The procedure attested in literature, which has been widely studied in the past years, consists of irradiating a glass slab and subsequently apply a chemical etching step. The results obtained by different research groups vary widely. In this paper we present a review of the most recent advancements of this technique discussing several critical factors that affect the aspect ratio, the length and the etching speed of the microchannel.

An efficient way to generate nanoscale laser-induced periodic surface structures (LIPSS) in rutile-type TiO 2 with frequency-converted femtosecond laser pulses at wavelengths around 400 nm is reported. Extended-area structuring on fixed and moving substrates was obtained by exploiting the line focus of a cylindrical lens. Under defined conditions with respect to pulse number, pulse energy and scanning velocity, two types of ripple-like LIPSS with high and low spatial frequencies (HSFL, LSFL) with periods in the range of 90 nm and 340 nm, respectively, were formed. In particular, lower numbers of high energetic pulses favour the generation of LSFL whereas higher numbers of lower energetic pulses enable the preferential creation of HSFL. Theoretical calculations on the basis of the Drude model support the assumption that refractive index changes by photo-excited carriers are a major mechanism responsible for LSFL. Furthermore, the appearance of random substructures as small as 30 nm superimposing low spatial frequency ripples is demonstrated and their possible origin is discussed.

Undoubtedly, we face a health threat unparalleled in our lives. At the same time, the corona disease is spreading, the danger is increasing, until this moment the infected people reached 656,690 cases, and 30397 death. Our health systems, our economies and our daily lives are being tested very harshly. The most vulnerable are the hardest hit-especially the elderly, those with pre-existing health problems, those without reliable health care, and those who live in poverty or are marginalized. The social and economic repercussions of the conjugation between the pandemic and the slowdown in economies will affect most of us for a few months. 1 It is time for us to get to know the photon better, through Ali Yousif's equations. These equations describe chemical reactions that are influenced by light variables. Ali's equations are equations that link chemistry, laser, and thermodynamics, they link the properties of a photon with the properties of the matters. They contain concepts such as enthalpy, free energy, and Gibbs energy that control any chemical reaction. Since the replication mechanism of the Corona virus is gust chemical reactions in laser considerations, then we can jam these reactions and create side reactions that kill the virus. Enzymes are highly organized materials, have specific jobs to do, any jamming will end up to death. Conversely, Gibbs energy (reaction enthalpy) is powerfully influence reaction, even organized reactions of enzymes, so anything change this Gibbs will effect reactions, photon lastly found his pathway to interfere reactions through Ali's equations. To recognize how that could be done, fellow me. This paper I began introduce COVID 19 virus, its behavior, pathogenicity through its RdRP enzymes, how this enzymes built up and how does it work. Next I introduced my equations and its relations with photon, chemical reactions, and then built a coherent idea about using laser to affect enzymes reactions.

- by Ali Yousif Hassan Edriss
- •
- Chemical Engineering, Microbiology, Laser Physics, Laser

High-quality carbon nanoparticles with controlled viscosity and high aqueous stability were prepared by liquid-phase laser ablation of a graphite target in deionized water. The size distribution was found to vary from 5 nm to 50 nm with mean size of 18 nm, in the absence of any reducing chemical reagents. Efficient generation of short chain polyynes was recorded for high laser repetition rates. Homogeneous and stable nanoparticle suspensions with viscosities ranging from 0.89 to 12 mPa.s were obtained by suspending the nanoparticles in different solvent mixtures such as glycerol–water and isopropanol–water. Optical properties were investigated by absorption and photoluminescence spectroscopy. Raman spectroscopy confirmed graphitic-like structure of nanoparticles and the surface chemistry was revealed by Fourier-transform infrared spectroscopy demonstrating sufficient electrostatic stabilization to avoid particle coagulation or flocculation. This paper present an exciting alternative method to engineer carbon nano-particles and their potential use as a ligand-free nano-ink for ink jet printing (jetting) applications.

Fiber lasers have the advantage of high beam quality, high efficiency, small size, air cooling and therefore much interest in the development of high power fiber laser systems have arisen recently in the world. Almost all commercially developed fiber lasers with nanosecond pulse duration, that are being used for material processing, are Q-switched systems. Vital parameters in the material processing such as repetition rate, pulse energy and pulse duration are correlated with each other and they cannot be adjusted independently in the Q-switch mechanism.
In this study, ytterbium doped all-fiber laser amplifier with 60 W average power and more than 20 kW peak power at 1 µm wavelength was developed, and its potential for processing of different material types is investigated. This master-oscillator power-amplifier (MOPA) architectured system is composed of pulses, produced by an electronically pumped diode, and amplified by a series of fiber amplifiers. In contrast with Q-switch lasers, MOPA architecture allows us to adjust pulse duration, repetition rate and power independently. Beam quality is nearly diffraction limited, and the typical M2 value is1.5. The system is an all-fiber one where the maximum pulse energy achieved at 100 kHz repetition rate is 0.6 mJ and minimum pulse duration is ~30 ns at this energy level. Due to multi-stage architecture and special precautions, the system works without a high amplified spontaneous emission (ASE) level and shows an optical efficiency of 76%. After development of the laser amplifier, and certification of its materials processing capability, an industrial prototype was configured by taking the cost-efficiency into account . The laser components were placed into a compact case which has a simple design for thermal cooling. The developed industrial laser amplifier prototype has several unique properties with respect to other equivalent MOPA design fiber lasers.
In material processing, high stability and high beam quality lead to high consistency. Reduced diameters of active and passive fiber cores and specially optimized fiber splices, which are used in the system architecture, result with higher beam quality thus the focusing is superior to many contemporary commercial lasers. As the intensity (areal power density) is the physical quantity that drives the nature of interaction of laser output with materials, the developed system offers long operation life-time due to its capability of operation at lower power levels than its contemporaries.
In order to demonstrate the efficiency and the ability of processing various different kinds of materials with the developed laser amplifier system, a multitude of processing applications such as micro drilling, solar cell edge isolation, deep engraving and color marking were tested on metal, semiconductor and insulator surfaces and the results are discussing in relationship with various system operation parameters.

ABSTRACT We have investigated the nonlinear optical properties, optical limiting thresholds, and figures of merits for five different phthalocyanine thin films, achieved through doping in PMMA polymer, using the Z-scan technique at 800 nm with 2 ps laser pulse excitation. From the open-aperture Z-scan data we derived that these molecules exhibit strong two photon absorption (2PA) with the nonlinear absorption coefficients in the range of 15-200 cm/GW.

- by Venugopal Rao Soma and +1
- •
- Laser Materials Processings - Photonic devices - Nonlinear optics

We study the dopant incorporation processes during thin-film fs-laser doping of Si and tailor the dopant distribution through optimization of the fs-laser irradiation conditions. Scanning electron microscopy, transmission electron microscopy, and profilometry are used to study the interrelated dopant incorporation and surface texturing mechanisms during fs-laser irradiation of Si coated with a Se thin-film dopant precursor. We show that the crystallization of Se-doped Si and micrometer-scale surface texturing are closely coupled and produce a doped surface that is not conducive to device fabrication. Next, we use this understanding of the dopant incorporation process to decouple dopant crystallization from surface texturing by tailoring the irradiation conditions. A low-fluence regime is identified in which a continuous surface layer of doped crystalline material forms in parallel with laser-induced periodic surface structures over many laser pulses. This investigation demon-Electronic supplementary material The online version of this article (strates the ability to tailor the dopant distribution through a systematic investigation of the relationship between fs-laser irradiation conditions, microstructure, and dopant distribution.

This paper presents the design of an index guided photonic crystal fiber which promises to yield very large birefringence (∼ 2.22 × 10 −2 ). Important optical properties, such as birefringence, single modeness, optical confinement, fiber dispersion, walk-off, etc., have been studied employing numerical simulation through finite difference time domain scheme. The fiber also promises a very small walk-off near optical communication wavelength.

In this paper we investigate the effects of visible to near infrared (NIR) laser illumination on the optical transmission (OT) and morphological (MC) alterations of thin, curved surfaces of polycarbonate (PC). The second harmonic of Nd:YAG laser (532 nm) and two diode lasers (665 and 980 nm) were used as illuminating sources. The morphological changes of the PC surfaces are determined using atomic force microscopy (AFM), demonstrating the appreciable changes caused by shorter wavelengths (higher energy). When analyzing the OT spectra of PC thin films, a measurable decrease in the OT of the PC samples which were illuminated by 532, 665 and 980 nm, in particular 532 nm, for energy densities greater than 25 J/cm 2 can be seen.

- by amir ehsani
- •
- Optics, Free Electron Lasers, Nonlinear Optics, Spectroscopy

This review gives an overview concerning the optical limiting (OL) properties of materials like porphyrins and phthalocyanines. It gives special attention to the phthalocyanine and porphyrin modulation aiming the achievement of effective systems in terms of OL performance through the appropriate combination and modulation of several structural components. The versatility of the methods of organic synthesis here considered permits the variation of the different chemical features, such as the nature of the ring substituents, the central atom, the ligands attached to the central atom and the degree of electronic conjugation of the macrocycle. Previous works on this field are referred, but the more recent developments are emphasised. Review with more than 100 references.

- by Benjamin Franta and +2
- •
- Materials Science, Photovoltaics, Laser Materials Processings - Photonic devices - Nonlinear optics, Silicon

This article is an idea of absolutely
speculation, but it came agree with an
experiment mentioned on reference no
5. (see references list). Diamond
Synthesis has been a dream to all
chemists throughout ages, like wise
gold, Ali’s equations once again found
a way to interpret and create these
materials.
The proverb says (if you could control
thermodynamics, you would control
nature), I say “any chemical reaction in this nature if science find a way to achieve it, my
equations capable to make it by itself”. So let us welcome the world-wide-going modern
chemistry.
In this paper I made a comparison between my calculations and an experiment, I found out the
intensity needed for sp3 & sp2 hybridization orbitals for graphite and diamonds is close by
experiment results. Then I made others steps about using these absorptions by inject more
intensity to turn sp2 to sp3 and vice versa.

- by Ali Yousif Hassan Edriss
- •
- Chemical Engineering, Physics, Quantum Physics, Chemistry

Our work is studying the optical nonlinearity properties of Chlorophyll-a doped epoxy resin polymer with TiO2 nanoparticle effect. Using EZ-scan technique with continuous wave Nd: Chlorophyll YAG laser operating at (532) nm wavelength as an excitation source. The samples exhibit absorption nonlinearities which due to saturable absorption (SA) process. The nonlinear refractive index n2 is a positive sign, indicates self-focusing optical nonlinearity process. The nonlinear refractive index n2, and the nonlinear absorption coefficient B are found to be of the order of 10-11 cm 2 /W and 10-1 cm/W respectively. The Tio2 nanoparticle concentration enhancing the nonlinear optical properties of samples.

- by Mustafa Jaber and +1
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- Laser, Laser Materials Processings - Photonic devices - Nonlinear optics, Optical Properties

We analyze the control of molecular orientation by nonresonant and quasiresonant two-color laser pulses
2+1 process. The laser pulses are assumed to be short with respect to the rotational period. In the nonresonant
case, we show that the efficiency of this strategy crucially depends on the polarizability and the hyperpolarizability
of the molecule. In the quasiresonant case, i.e., if the 2 frequency is in quasiresonance with a
vibrational frequency, one can improve the orientation by adjusting the detuning. The best orientation is
obtained for an optimal value of the detuning, which is different from zero

- by Ronald Tehini
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- Quantum Computing, Quantum Physics, Laser Spectroscopy, Laser Physics

Detailed program of the HPLS&A conference, www.hplsa2018.com
Proceedings will be published by SPIE

- by Paolo Di Lazzaro
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- Laser Spectroscopy, Laser Physics, Free Electron Lasers, Laser

The Kingdom of Saudi Arabia is one of the leading date producing countries. Unfortunately , this important fruit crop is under great threat from the red palm weevil (RPW) (Rhynchophorus f errugineus), which is a highly invasive pest. Several techniques, including visual inspection, acoustic sensors, sniffer dogs, and pheromone traps have been tried to detect the early stages of a RPW infestation; however, each method has suffered certain logistical and implementation issues. We have applied laser induced breakdown spectroscopy (LIBS) for the early detection of RPW infestation. Through the analysis of the observed LIBS spectra of different infested and healthy samples, we have found presence of Ca, Mg, Na, C, K elements and OH, CN molecules. The spectra also reveal that with the population growth of the pest, the intensity of Mg and Ca atomic lines in LIBS spectra increases rapidly. Similar behavior is observed in the molecular lines of LIBS spectra. The obtained results indicate that the LIBS technique can be used for the early detection of RPW infestation without damaging the date palms.

- by W Aslam Farooq and +1
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- Laser Spectroscopy, Laser Physics, Laser Materials Processings - Photonic devices - Nonlinear optics

Lazer ile malzeme işleme uygulamaları büyük bir hızla gelişmekte ve yaygınlaşmaktadır. Yüksek hassasiyete dayalı mikroişleme, güneş pillerinin fabrikasyon sırasında hasarsız kesilmesi ve kenar izolasyonlarının gerçekleştirilmesi, sert endüstriyel malzemelerin ve ısıya hassas biyomedikal malzemelerin mikroişlenmesine yönelik uygulamaları büyük önem kazanmaktadır. Yüksek hassasiyetle mikroişleme için nanosaniye ve daha uzun atımlı lazerler, oluşan termal etkiler nedeniyle uygun olmamakta, daha kısa atımların kullanılması gerekmektedir. Isınma olmaksızın malzeme işleme uygulamaları yaklaşık 10 pikosaniye veya daha kısa atımlar gerektirmekle birlikte, malzeme işleme hızı da nanosaniye atımlara göre 10-100 kat daha yavaştır. 100 ps mertebesinde atımlar ısıl etkileri büyük oranda elimine edip, işlem hızında nanosaniye atımlara daha yakın performans göstererek cazip bir ara rejim oluşturmaktadır. Bu çalışmada yüksek hassasiyette malzeme işlemek için 50-ps, 15W, 30MHz,Yb-katkılı fiber lazer yükselteç sistemi geliştirilmiş ve çeşitli malzemeler üzerinde uygulamalar yapılmıştır.

Knowledge about the temperature distribution inside solid-state laser crystals is essential for calculation of thermal phase shift, thermal lensing, thermally induced birefringence, and heat-induced crystal bending. Solutions for the temperature distribution for the case of steady-state heat loading have appeared in the literature only for simple cylindrical crystal shapes and are usually based on numerical techniques. For the first time, to our knowledge, a full analytical solution of the heat equation for an anisotropic cubic cross-section solid-state crystal is presented. The crystal is assumed to be longitudinally pumped by a Gaussian pump profile. The pump power attenuation along the crystal and the real cooling mechanisms, such as convection, are considered in detail. A comparison between our analytical solutions and its numerical counterparts shows excellent agreement when just a few terms are employed in the series solutions.

Development of All-Optical Logic functions for All-Optical Signal Processing, have attracted considerable interest in recent years. Efforts have been made to realize All-Optical Logic devices utilizing several non-linear effects and Interferometric configurations such as Mach-Zehnder Interferometer (MZI), Ultrafast Non-Linear Interferometer (UNI) & Sagnac Interferometers. Out of all Interferometric configurations, All-Optical logic devices based on Sagnac Interferometer are attractive, due to their ability to operate at high bit rates & low latency. This paper is an overview of Sagnac Interferometer fundamentals & its variants. All-Optical Binary as well as Multi-Valued (MV) Logic devices based on Sagnac Interferometers are also illustrated.

Multiphoton absorption via ultrafast laser focusing is the only technology that allows a three-dimensional structural modification of transparent materials. However, the magnitude of the refractive index change is rather limited, preventing the technology from being a tool of choice for the manufacture of compact photonic integrated circuits. We propose to address this issue by employing a femtosecond-laser-induced electronic band-gap shift (FLIBGS), which has an exponential impact on the refractive index change for propagating wavelengths approaching the material electronic resonance, as predicted by the Kramers–Kronig relations. Supported by theoretical calculations, based on a modified Sellmeier equation, the Tauc law, and waveguide bend loss calculations, we experimentally show that several applications could take advantage of this phenomenon. First, we demonstrate waveguide bends down to a submillimeter radius, which is of great interest for higher-density integration of fs-laser-written quantum and photonic circuits. We also demonstrate that the refractive index contrast can be switched from negative to positive, allowing direct waveguide inscription in crystals. Finally, the effect of the FLIBGS can compensate for the fs-laser-induced negative refractive index change, resulting in a zero refractive index change at specific wavelengths, paving the way for new invisibility applications.

M-square measurements since the inception of the ISO 11146-1 measurement standard of 1996 has been one that has been difficult even for a seasoned veteran of such measurements. Variations of more than 10% are not uncommon for the same measurement tool on the same laser being measured. Much of the variation comes from alignment, the motion involved (time averaged based), complex attenuation techniques which often include variable neutral density filters and the type of sensors employed. Moreover, setup times for the instrument can take hours and the measurements themselves many minutes. Measurement of a laser or a laser systems' M-square should be as simple as measuring the power of the laser. In that one aligns the laser to the device; put the device in self calibration mode; make a measurement. In 2012 the authors developed a passive optical design that provided real-time M-square measurement of a laser or laser system but nevertheless still required calibration of the key optics within the system: a Fabry-Perot etalon pair and their spacing in order to obtain an accurate M-square result. Using existing data from the sensor along with a simple ray tracing technique, the etalon spacing can be determined with high accuracy through the deconvolution of the data from the sensor; thereby eliminating a separate time consuming calibration. The key calibration information can now be obtained in a fraction of a second without any effort on the part of the user.

The effects of laser irradiation on the mechanical response of polycrystalline zirconium (Zr) have been investigated. Zr samples were irradiated with an excimer (KrF) laser (λ ≈ 248 nm, τ ≈ 18 ns and repetition rate ≈ 30 Hz). The irradiation was performed in the ambient environment of a gas mixture containing (CO 2 : N 2 : He) under a filling pressure of 20 Torr by varying laser fluences ranging from 3.8 to 5.1 J cm −2. The surface and structural modification of the irradiated targets were investigated using a scanning electron microscope (SEM) and x-ray diffractometer (XRD). In order to explore the mechanical properties of the irradiated Zr, the tensile testing and Vickers microhardness testing techniques were employed. SEM analysis reveals the grain growth on the irradiated Zr surfaces; however, for increasing fluence up to 4.7 J cm −2 , the appearance of the grains becomes more distinct with an increase in their number density and decrease in size. For the maximum fluence of 5.1 J cm −2 , the grains completely vanish and the surface becomes diffusive. XRD analysis reveals the appearance of new phases of ZrN and ZrO 2. The variation in the peak intensity is observed to be anomalous, whereas the decreasing trend in the crystallite size and residual stresses is observed with increasing fluence. The microhardness analysis reveals the increasing trend in surface hardness with increasing fluence. The tensile testing demonstrates the anomalous behaviour of the yield stress and ultimate tensile strength with increasing fluence.

Femtosecond laser irradiation followed by chemical etching (FLICE) with hydrogen fluoride (HF) is an emerging technique for the fabrication of directly buried, three-dimensional microfluidic channels in silica. The procedure, as described in literature, consists of irradiating a silica slab followed by chemical etching using hydrogen fluoride. With aqueous HF the etching process is diffusion-limited and is self-terminating, leading to maximum microchannel lengths of about 1.5 mm, while the use of low-pressure gaseous HF etchant can quickly produce 3 mm long channels with an aspect ratio (Length/Diameter) higher than 25. By utilizing this methodology the aspect ratio is not constant, but depends on the length of the channel. When the microchannel is short the aspect ratio increases quickly until it reaches a maximum length at around 1400 µm. Thereafter the aspect ratio starts to decrease slowly. In this paper we present a variation of the low-pressure gaseous HF etching method, which is based on the dynamic displacement of the etchant. This method results in a 13% increase in the aspect ratio (L/D = 29) at the expense of a low etching speed (4 µm/min).

The spectral properties and Z-scan technique were used to study the nonlinear absorption coefficient (β) and nonlinear refractive coefficient (n2) of α-Chlorophyll dye solutions. A (100 mW) Neodymium-doped Yttrium Garnet (Nd: YAG) continuous laser (CW) with second harmonic generate at wavelength (532 mW) was used to evaluate open and closed zscan setup. It is shown that the n2, β, and χ (3) is of the order of 10-12 , 10-2 and 10-10 respectively.

This book discusses my equations (Ali’s equations) compared with related scientific papers and already made devices that are working now, these devices are made for some purposes such as:
High power energetic laser applications: such as nuclear exploration, astrophysics, Electromagnetic Bomb or Gun, Weather controlling by high density Laser (Teramobile), and so on.
Industrial applications such as: laser cutting machines, laser welding, photochemical reactions, communications, and so on.
Medicines purposes: cancer medications, dentistry’s applications, physiotherapy’s applications, laser for LASIK, Wound healing, pain relief and healing with, laser therapy, osteoarthritis, laser for Glaucoma, and so on.
I will use here in my paper some given information like (photon energies and intensities) which obtained from Device’s Catalog and then substitute these information on my equations to evaluate and modify it.
This strange idea came out after all my failed attempts to do confirmed experiments.
In this paper I adopt the screenshots I took from advertising devices’ companies with putting web links to them, then I discuss through comparing with my equations.
In the beginning I will give an introduction to Ali’s equations and pointing to my reading about, then I will discuss with pictures-if I could- and papers why these equipment act like that. This step is servicing my situation because there are no experiments done to approve my equations so I adopt the comparison between my results and devices’ parameters or papers’ results.
In this book I follow a systemic graduation from high dense and energetic lasers to moderate until very low energy and density trying to give physical explanation according to my equations.
Then I adopt new ideas about the optimum using of these equations especially in telecommunications and satellite efficiency.
Finally I would like to thank my God to give me the power for writing this book. And I dedicate this book to my daughter Isra and to all mankind.

- by Ali Yousif Hassan Edriss
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- Chemical Engineering, Physics, Nuclear Physics, Quantum Physics

Optical fiber cables are materials whose core is made of silica and other materials such as chalcogenide glasses; they transmit a digital signal via light pulses through an extremely thin strand of glass. The light propagates and is being guided by the core which is surrounded by the cladding. Light travels in the optical fiber in the form of total internal reflection in the core of the fibers. The flexibility, low tensile strength, low signal loss, high bandwidth and other characteristics of optical fibers favors it for use as a delay medium in many applications. Another favorable characteristic of optical fiber delay lines is are their relative insensitivities to environmental effects and electromagnetic interferences. The immunity of optical fibers to interferences and their less weight added advantages to it for use as delay medium. Single-mode and multi-mode are the two most popular types of optical fibers. Single-mode fibers have good propagation and delay properties with a minimal loss that allows the signal to propagate in a large distance with insignificant distortion or attenuation. The percentage of power transmission of single-mode fibers is found to be higher than that of the multi-mode fibers. It is, therefore, a preferred type for use as a delay line. In this paper, relative studies of the two optical fibers modes, and the results of power input/output measurement of the two modes are presented with a view to coming up with a better type for use as a delay medium.

In this paper, a model describing the thermal effects on the optical parametric oscillator (OPO) of Gaussian continuous waves in double-pass cavities is presented. Eight equations, including forward and backward non-linear waves, heat, and thermally induced phase mismatching equations, were coupled and solved simultaneously to investigate the effect of heat generation on the OPO's efficiency. The model was applied for a periodically poled MgO:LiNbO 3 crystal with an excellent agreement with experimental data. The numerical calculations have been carried out by a homemade code written in Intel FORTRAN, which used a finite difference method.

The absorption, scattering, and anisotropy coefficients of the fat emulsion Intralipid-10% have been measured at 457.9, 514.5, 632.8, and 1064 nm. The size and shape distributions of the scattering particles in Intralipid-10% were determined by transmission electron microscopy. Mie theory calculations performed by using the particle size distribution yielded values for the scattering and anisotropy coefficients from 400 to 1100 nm. The agreement with experimental values is better than 6%.

Gold nanoparticles (NPs) exhibit strong surface plasmon resonance (SPR) in the visible spectral region. Lithium Zinc Calcium Fluoroborate glasses embedded with Au NPs were synthesized by conventional melt quench technique. The gold NPs embedded glasses exhibited dichroic nature. A small kink around 44.61 ∘ in the X-ray diffraction (XRD) pattern suggests the presence of Au (2 0 0) in the matrix. High resolution-transmission electron microscopic (HR-TEM) measurements further confirmed the existence of spherical and ellipsoidal Au NPs. Thermogravimetric analysis (TGA) reveals the role of network modifiers in the matrix as the glasses that contained higher concentration of lithium oxide exhibits lower T g thereby resulting in creation of more non bridging oxides (NBO's). The Z-Scan studies were performed under non-resonant condition (800 nm) to analyze the application of these glasses for optical limiting devices.