1. Preparação do Substrato <ol><li> Corte de 1 cm x 1 substratos de silício de um centímetro lâmina de silício, silício é bom para a caracterização SEM (vista de avião e seção transversal). </li><li> Cortar vidro de 1 cm x 1 cm (de soda-cal, 1 mm de espessura), o vidro é ideal para a caracterização óptica e eléctrica. </li><li> Se os contactos são necessárias em substratos de vidro, os contactos Au pode ser evaporado em vácuo, usando uma máscara. Depósito de 10 nm de Cr como uma camada intermediária para melhorar a adesão de Au, depósito 50 nm de Au. </li><li> Cortada 1 cm x 1 cm de amostra de polímero (por exemplo, etileno tetrafluoroetileno, ETFE). </li><li> Limpar os substratos por sonicação em isopropanol, durante 5-10 min e enxaguar em isopropanol, seca utilizando um fluxo de N 2. </li></ol> 2. Alinhamento a laser e Seleção de parâmetros do laser <ol><li> De aquecimento a laser Nd: YAG e seleccione emissão IV harmónica (266 nm de comprimento de onda), utilizando um gerador de harmónicas quarto (FHG), constituído por dois sigeradores cond harmônicas (SHG) em cascata. </li><li> Montar um peso de 2%. Al 2 O 3:. ZnO alvo circular (diâmetro de 2 &quot;), em que o manipulador alvo Alinhar o ponto de laser no centro do alvo, iniciar a rotação e translação de destino e definir o intervalo vertical máxima Verificar que o ponto de laser nunca toca a externa. anel de aço utilizado para fixar o alvo. O alvo é movido com um movimento de roto-translacional de ter de ablação uniforme de toda a superfície do alvo. </li><li> Selecione a taxa de repetição (por exemplo, 10 Hz) e pulso de energia (por exemplo, 75 mJ). Ajuste de pulso de energia e monitorar a estabilidade do laser por um medidor de energia. </li><li> Mover a lente de focagem para a posição seleccionada e usar um pedaço de papel sensível ligado ao alvo para medir o tamanho do ponto. Para qualquer posição de focagem das lentes de incêndio disparos de laser 1-5 sobre o papel. Seleccionar uma posição da lente para ter uma fluência do laser de cerca de 1 J / cm 2. </li></ol> 3. Criação de um PLDSeleção d de parâmetros de deposição <ol><li> Alinhamento da posição do substrato <ol><li> Montar uma chapa circular de papel de cerca de 2 &quot;de diâmetro como um substrato para os testes de alinhamento. </li><li> Mover o suporte do substrato a uma distância do alvo-para-substrato TS d = 50 mm. </li><li> Iniciar o bombeamento para baixo na câmara de com bombas primárias e turbomolecular até que o nível de vácuo atinge 10 -2 Pa. </li><li> Selecione um tipo de gás (oxigênio, por exemplo) e ajustar a velocidade de bombeamento e fluxo de gás para ter a pressão de gás adequado (ver secções 4 e 5). Ajuste xy posição do manipulador de substrato fora do eixo em relação ao centro da pluma de obter a espessura da película uniforme sobre uma coroa circular. </li><li> Comece a ablação, removendo o feixe metros rolha / potência. Se o alvo é novo ou se não tiver sido utilizada durante muito tempo, esta pré-ablação é necessário limpar o alvo. </li><li> Pare ablação quando um depósito pode ser visto no paper olhando de uma janela. </li></ol></li><li> Determinação do comprimento da pluma plasma <ol><li> Siga os passos 3.1.1. a 3.1.5, durante a ablação tirar fotos com uma câmera digital com 0,5 - 1 vez acumulação de seg a média de plumas de plasma diferentes. </li><li> Medir o comprimento da pluma visível plasma a partir das imagens, tendo d TS como referência (ver figura 3). </li></ol></li><li> A calibração da espessura do filme <ol><li> Mover o substrato longe do alvo (ou seja, de 100 mm e mais) e deslocar o equilíbrio Micro-quartzo (QCM), a uma distância igual a d TS a partir do alvo. </li><li> Depósito 1000 laser (ou seja, 1 &#39;40&#39;&#39;) e medir o valor da massa depositada, em seguida, passar a QCM distância. </li><li> Montar um substrato de Si como em 1.1. </li><li> Depositar uma amostra de teste (por exemplo, 18.000 disparos de laser, ou seja, 30 &#39;) e usar imagens seccionais cruzadas SEM para calibrate a taxa de deposição (nm / pulso). </li></ol></li></ol> 4. Deposição de nanoengineered AZO Films <ol><li> Montar os substratos preparados como no ponto 1 em que o manipulador suporte de amostras usando fita adesiva. </li><li> Siga os passos 3.1.2 - 3.1.3. </li><li> Iniciar a rotação do substrato. </li><li> Deposição de filmes compactos AZO <ol><li> Ligar a pistola de iões e de energia de iões conjunto a 100 eV de energia de RF, a 75-100 W e do fluxo de gás Ar a 20 sccm (a pressão está na gama de 10 Pa -2). Substratos limpos com Ar + íon de armas por 5-10 min. Após a entrada de gás de tratamento de limpeza e estreita para baixo da câmara de bomba para remover Argon. </li><li> Insira o gás oxigênio e ajustar bombeamento velocidade e fluxo de gás para ter dois de oxigênio Pa. </li><li> começar a ablação e depósito para 18.000 disparos (30 &#39;). Durante a ablação de verificação de que o comprimento da pluma é o mesmo, tal como determinado no passo 3.2. </li><li> parar de ablação, g pertocomo entrada, bombear a câmara. </li></ol></li><li> Deposição de filmes hierarquicamente estruturados AZO <ol><li> Insira o gás oxigênio e ajustar a velocidade de bombeamento e fluxo de gás para ter 160 oxigênio Pa. </li><li> começar a ablação e depósito para 18.000 disparos (30 &#39;). Durante a ablação de verificação de que o comprimento da pluma é o mesmo, tal como determinado no passo 3.2. </li><li> parar de ablação, entrada de gás perto, bombear a câmara. </li></ol></li><li> Alivie a câmara e recolher amostras </li></ol> 5. Caracterização elétrica e óptica <ol><li> Medir as propriedades de avião-transporte, utilizando quatro sondas de técnicas (ou seja, Van der Pauw método). Ver Figura 4 para um esquema dos contatos. Os valores típicos da corrente estão na sonda mA 1-10 mA. As medições são realizadas através de uma área de amostra reduzido para 0,7 cm x 0,7 centímetros de assegurar uma melhor uniformidade de espessura (cerca de 5%). </li><li> Medir a optical transmitância da amostra e do substrato nu. Corrigir os espectros para a contribuição de substrato através da criação de uma intensidade na interface vidro / película. Para um processo de correcção preciso garantir que a amostra é montada com o substrato de vidro voltada para o feixe incidente. Determinar a transparência da luz visível por meio do cálculo da transmitância média na gama de 400-700 nm. Use uma esfera de diâmetro 150 milímetros integrando para medir a fracção da luz dispersa, o factor de Haze pode ser calculada dividindo a fracção dispersa pela luz total transmitida (ou seja, para a frente e dispersa transmitida), ver Figura 5. </li></ol>

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A forma pluma plasma está intimamente relacionado com o processo de ablação, em especial na presença de um gás; monitorização da pluma plasma por inspecção visual é importante para controlar a deposição. Ao depositar um óxido de metal por ablação de um alvo de óxido, o oxigênio é necessário para suportar as perdas de oxigênio durante o processo de ablação. Com menor pressão de gás de oxigénio de fundo, o material depositado pode ter vagas de oxigénio. Este efeito é reduzido através do aumento...

A deposição laser pulsada (PLD) emprega a ablação por laser de um alvo sólido que resulta na formação de um plasma de espécies extirpadas que podem ser depositados sobre um substrato de um filme para crescer (ver Figura 1) 1. A interacção com a atmosfera do fundo (inerte ou reactivo) podem ser utilizados para induzir a nucleação homogénea aglomerado na fase de gás (veja a Figura 2) 2,3. A nossa estratégia para a síntese de material por PLD é baseada na afinação das propriedades dos materiais em uma abordagem de baixo para cima através do controlo rigoroso da dinâmica do plasma gerado no processo de PLD. Tamanho do cluster energia cinética e composição pode ser variada por uma configuração apropriada dos parâmetros de deposição, que afectam o crescimento de filmes e resultam em alterações morfológicas e estruturais, 4,5. Ao explorar o método descrito aqui, foi demonstrado, por um certo número de óxidos (por exemplo, WO 3, Ag 4 O 4, Al 2 O 3 and TiO 2), com a capacidade de afinar a morfologia, a densidade, a porosidade, grau de ordem estrutural, estequiometria e fase, modificando a estrutura do material no 6-11 nanoescala. Isto permite que o desenho de materiais para aplicações específicas 12-16. Com referência às aplicações fotovoltaicas, sintetizamos TiO 2 nanoestruturado hierarquicamente organizado por nanopartículas de montagem (&lt;10 nm) de um nano-e mesoestrutura que se assemelha a uma &#39;floresta de árvores &quot;13 mostrando resultados interessantes quando empregado como fotoanodos em corantes em células solares sensibilizadas (DSSC ) 17. Com base nestes resultados anteriores que descrevem o protocolo para a deposição de Al-ZnO dopados (AZO) filmes como um óxido condutor transparente. Óxidos transparentes condutores (TCOs) são bandgap elevada (&gt; 3 eV) materiais convertidos em condutores por dopagem pesada, exibindo resistividade &lt;10 -3 ohm-cm e mais de 80% transmi ópticottance na faixa visível. Eles são um elemento chave para muitas aplicações, tais como telas de toque e células solares 18-21 e eles são normalmente cultivadas por diferentes técnicas, tais como sputtering deposição por laser, pulsante, deposição de vapor químico, spray pirólise e com métodos de solução à base de químicos. Entre TCOs, índio-estanho-óxido (ITO) tem sido largamente estudada por sua resistividade baixa, mas tem o inconveniente do custo elevado e baixa disponibilidade de índio. A investigação está agora caminhando para índio sistemas livres como 2 SnO F-dopado (FTO), Al-dopado com ZnO (AZO) e F-dopado com ZnO (FZO). Eletrodos capazes de proporcionar uma gestão inteligente da luz incidente (armadilhas de luz) são particularmente interessantes para aplicações fotovoltaicas. Para explorar a possibilidade de dispersão de luz visível por meio de estruturas e morfologias modulados a uma escala comparável com o comprimento de onda da luz (por exemplo, 300-1,000 nm), um bom controlo sobre omorfologia filme e em arquiteturas de montagem de cluster é necessário. Em particular, descreve-se como a afinar a morfologia e estrutura de filmes AZO. Compact AZO depositados a baixa pressão (2 oxigénio Pa) e à temperatura ambiente, é caracterizada por baixa resistividade (4,5 x 10 ohm cm -4) e a transparência da luz visível (&gt; 90%), que é competitiva com AZO depositado a altas temperaturas, enquanto AZO estruturas hierárquicas são obtidos por ablação de O 2 em pressões superiores a 100 Pa. Estas estruturas exibem uma capacidade de espalhamento de luz forte com um factor de névoa de até 80% e mais 22,23.

<table border="1"><tbody><tr><td> Nome do reagente / Material </td><td> Companhia </td><td> Número de catálogo </td></tr><tr><td> Laser pulsado </td><td> Continuum-Quantronix </td><td> Powerlite 8010 </td></tr><tr><td> Medidor de energia </td><td> Coerente </td><td> FieldMaxII-TO </td></tr><tr><td> Ion Gun </td><td> Dep. Mantis </td><td> RFMax60 </td></tr><tr><td> Controlador de fluxo de massa </td><td> Mks </td><td> 2179 ° </td></tr><tr><td> Microbalança de Cristal de Quartzo </td><td> Infcon </td><td> XTC / 2 </td></tr><tr><td> Gás de fundo </td><td> Rivoira-Praxair </td><td> 5,0 oxigênio </td></tr><tr><td> Alvo </td><td> Kurt Lesker </td><td> (Feito a pedido) </td></tr><tr><td> Isopropanol </td><td> Sigma Aldrich </td><td> 190764-2L </td></tr><tr><td> Fonte metros </td><td> Keithley </td><td> K2400 </td></tr><tr><td> Ímã Kit </td><td> Ecopia </td><td> 0.55T-Kit </td></tr><tr><td> Espectrofotômetro </td><td> PerkinElmer </td><td> Lambda 1050 </td></tr></tbody></table>

fabrication of nano-engineered transparent conducting oxides by pulsed laser deposition

Nanossegundo deposição por laser pulsado (PLD), na presença de um gás de fundo permite a deposição de óxidos de metal com sintonizável morfologia, estrutura, densidade e estequiometria de um controlo adequado das plasmáticas dinâmica de expansão da pluma. Tal versatilidade pode ser explorada para produzir filmes nanoestruturados de nanoporoso compacto e denso que caracterizado por um conjunto hierárquico de nano-agregados. Em particular, descrevemos a metodologia detalhada para fabricar dois tipos de Al-ZnO dopados (AZO) filmes como eléctrodos transparentes em dispositivos fotovoltaicos: 1) a baixa pressão de O2, filmes compactos com uma condutividade eléctrica e fechar a transparência óptica do estado da arte óxidos condutores transparentes (TCO) podem ser depositados à temperatura ambiente, para ser compatível com materiais sensíveis ao calor, tais como os polímeros utilizados em células fotovoltaicas orgânicas (OPV), 2) de dispersão de luz altamente estruturas hierárquicas semelhante a uma floresta de nano-árvores são produced a pressões mais elevadas. Estas estruturas mostram factor de Haze elevada (&gt; 80%) e pode ser explorada para aumentar a capacidade de captura de luz. O método aqui descrito para os filmes AZO pode ser aplicado a outros óxidos metálicos relevantes para aplicações tecnológicas, tais como o TiO 2, Al 2 O 3, WO 3 e 4 Ag O 4.

A deposição de AZO pelo PLD em atmosfera de oxigênio produz compactos filmes transparentes condutores com baixa pressão de gás de fundo (ou seja, 2 Pa) e mesoporosos floresta-como estruturas constituídas por conjuntos montados hierarquicamente a altas pressões (ou seja, 160 Pa). O material é constituído por domínios nanocristalinos, cujo tamanho é máxima (30 nm) a 2 Pa 22. Devido a colisões entre as espécies extirpadas e os gases de fundo, a forma e...

Watch this Scientific Journal Video about Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition at JoVE.com

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Descreve-se o método experimental para depositar finas películas de óxidos nanoestruturados por nanossegundo deposição por laser pulsado (PLD), na presença de um gás de fundo. Ao usar esse método Al-dopados ZnO (AZO) filmes, de compacto para hierarquicamente estruturado como nano-árvores de florestas, pode ser depositado.

Fabricação de Nano-engenharia transparentes Óxidos Realização por deposição por laser pulsado

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

fabrication-nano-engineered-transparent-conducting-oxides-pulsed

Research

JoVE Journal

Engineering

15.4K visualizações.  Politecnico di Milano. Descreve-se o método experimental para depositar finas películas de óxidos nanoestruturados por nanossegundo deposição por laser pulsado (PLD), na presença de um gás de fundo. Ao usar esse método Al-dopados ZnO (AZO) filmes, de compacto para hierarquicamente estruturado como nano-árvores de florestas, pode ser depositado.

Vídeo: Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment1-11.
Early plasma evolution has been captured through pump-probe shadowgraphy1-3 and interferometry1,4-7. However, the studied time frames and applied laser parameter ranges are limited. For example, direct examinations of plasma front locations and electron number densities within a delay time of 100 picosecond (ps) with respect to the laser pulse peak are still very few, especially for the ultrashort pulse of a duration around 100 femtosecond (fs) and a low power density around 1014 W/cm2. Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions12. The detailed setup strategy and procedures of this high precision measurement will be illustrated in this paper. The rationale of the measurement is optical pump-probe shadowgraphy: one ultrashort laser pulse is split to a pump pulse and a probe pulse, while the delay time between them can be adjusted by changing their beam path lengths. The pump pulse ablates the target and generates the early plasma, and the probe pulse propagates through the plasma region and detects the non-uniformity of electron number density. In addition, animations are generated using the calculated results from the simulation model of Ref. 12 to illustrate the plasma formation and evolution with a very high resolution (0.04 ~ 1 ps).
Both the experimental method and the simulation method can be applied to a broad range of time frames and laser parameters. These methods can be used to examine the early plasma generated not only from metals, but also from semiconductors and insulators.

An experimental method to examine the early plasma evolution induced by ultrashort laser pulses is described. Using this method, high quality images of early plasma are obtained with high temporal and spatial resolutions. A novel integrated atomistic model is used to simulate and explain the mechanisms of early plasma.

Investigação da Evolução Plasma Precoce Induzida por Pulsos ultracurtos de laser

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a ...

Engenharia

Fabrication of Spatially Confined Complex Oxides

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from the inherent strong electron correlations that reside within them. These materials can also possess electronic phase separation in which regions of vastly different resistive and magnetic behavior can coexist within a single crystal alloy material. By reducing the scale of these materials to length scales at and below the inherent size of the electronic domains, novel behaviors can be exposed. Because of this and the fact that spin-charge-lattice-orbital order parameters each involve correlation lengths, spatially reducing these materials for transport measurements is a critical step in understanding the fundamental physics that drives complex behaviors. These materials also offer great potential to become the next generation of electronic devices 1-3. Thus, the fabrication of low dimensional nano- or micro-structures is extremely important to achieve new functionality. This involves multiple controllable processes from high quality thin film growth to accurate electronic property characterization. Here, we present fabrication protocols of high quality microstructures for complex oxide manganite devices. Detailed descriptions and required equipment of thin film growth, photo-lithography, and wire-bonding are presented.

We describe the use of pulsed laser deposition (PLD), photolithography and wire-bonding techniques to create micrometer scale complex oxides devices. The PLD is utilized to grow epitaxial thin films. Photolithography and wire-bonding techniques are introduced to create practical devices for measurement purposes.

Fabricação de óxidos complexos espacialmente confinados

Complex materials such as high Tc superconductors, multiferroics, and colossal magnetoresistors have electronic and magnetic properties that arise from ...

Making Record-efficiency SnS Solar Cells by Thermal Evaporation and Atomic Layer Deposition

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent thermal evaporation, and it absorbs visible light strongly. However, for a long time the record power conversion efficiency of SnS solar cells remained below 2%. Recently we demonstrated new certified record efficiencies of 4.36% using SnS deposited by atomic layer deposition, and 3.88% using thermal evaporation. Here the fabrication procedure for these record solar cells is described, and the statistical distribution of the fabrication process is reported. The standard deviation of efficiency measured on a single substrate is typically over 0.5%. All steps including substrate selection and cleaning, Mo sputtering for the rear contact (cathode), SnS deposition, annealing, surface passivation, Zn(O,S) buffer layer selection and deposition, transparent conductor (anode) deposition, and metallization are described. On each substrate we fabricate 11 individual devices, each with active area 0.25 cm2. Further, a system for high throughput measurements of current-voltage curves under simulated solar light, and external quantum efficiency measurement with variable light bias is described. With this system we are able to measure full data sets on all 11 devices in an automated manner and in minimal time. These results illustrate the value of studying large sample sets, rather than focusing narrowly on the highest performing devices. Large data sets help us to distinguish and remedy individual loss mechanisms affecting our devices.

Tin sulfide (SnS) is a candidate material for Earth-abundant, non-toxic solar cells. Here, we demonstrate the fabrication procedure of the SnS solar cells employing atomic layer deposition, which yields 4.36% certified power conversion efficiency, and thermal evaporation which yields 3.88%.

Fazendo Record-eficiência SnS Células solares por evaporação térmica e Deposição Camada Atómica

Tin sulfide (SnS) is a candidate absorber material for Earth-abundant, non-toxic solar cells. SnS offers easy phase control and rapid growth by congruent ...

Selective Area Modification of Silicon Surface Wettability by Pulsed UV Laser Irradiation in Liquid Environment

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of biosensing devices. We report on a protocol of using KrF and ArF lasers irradiating Si (001) samples immersed in a liquid environment with low number of pulses and operating at moderately low pulse fluences to induce Si wettability modification. Wafers immersed for up to 4 hr in a 0.01% H2O2/H2O solution did not show measurable change in their initial contact angle (CA) ~75&#176;. However, the 500-pulse KrF and ArF lasers irradiation of such wafers in a microchamber filled with 0.01% H2O2/H2O solution at 250 and 65 mJ/cm2, respectively, has decreased the CA to near 15&#176;, indicating the formation of a superhydrophilic surface. The formation of OH-terminated Si (001), with no measurable change of the wafer&#8217;s surface morphology, has been confirmed by X-ray photoelectron spectroscopy and atomic force microscopy measurements. The selective area irradiated samples were then immersed in a biotin-conjugated fluorescein-stained nanospheres solution for 2 hr, resulting in a successful immobilization of the nanospheres in the non-irradiated area. This illustrates the potential of&#160;the method for selective area biofunctionalization and fabrication of advanced Si-based biosensing architectures. We also describe a similar protocol of irradiation of wafers immersed in methanol (CH3OH) using ArF laser operating at pulse fluence of 65 mJ/cm2 and in situ formation of a strongly hydrophobic surface of Si (001) with the CA of 103&#176;. The XPS results indicate ArF laser induced formation of Si&#8211;(OCH3)x compounds responsible for the observed hydrophobicity. However, no such compounds were found by XPS on the Si surface irradiated by KrF laser in methanol, demonstrating the inability of the KrF laser to photodissociate methanol and create -OCH3 radicals.

We report on a process of in situ alteration of HF treated Si (001) surface into a hydrophilic or hydrophobic state by irradiating samples in microfluidic chambers filled with&#160;H2O2/H2O solution (0.01%-0.5%) or methanol solutions using pulsed UV laser of a relative low pulse fluence.

Seletiva Área Modificação de Superfície Wettability Silicon por Pulsed Laser irradiação UV em meio líquido

The wettability of silicon (Si) is one of the important parameters in the technology of surface functionalization of this material and fabrication of ...

Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.

A protocol to detect and automate mode locking in a pre-adjusted nonlinear polarization rotation fiber laser is presented. The detection of a sudden change in the output polarization state when mode locking occurs is used to command the alignment of an intra-cavity polarization controller in order to find mode-locking conditions.

Automação de Modo de bloqueio em uma rotação do laser da fibra não-linear de polarização através de medidas de polarização de saída

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a ...

Fabrication of 1-D Photonic Crystal Cavity on a Nanofiber Using Femtosecond Laser-induced Ablation

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using femtosecond laser-induced ablation. We show that thousands of periodic nano-craters are fabricated on an optical nanofiber by irradiating with just a single femtosecond laser pulse. For a typical sample, periodic nano-craters with a period of 350 nm and with diameter gradually varying from 50 - 250 nm over a length of 1 mm are fabricated on a nanofiber with diameter around 450 - 550 nm. A key aspect of such a nanofabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. Moreover, the single-shot fabrication makes it immune to mechanical instabilities and other fabrication imperfections. Such periodic nano-craters on nanofiber, act as a 1-D PhC and enable strong and broadband reflection while maintaining the high transmission out of the stopband. We also present a method to control the profile of the nano-crater array to fabricate apodized and defect-induced PhC cavities on the nanofiber. The strong confinement of the field, both transverse and longitudinal, in the nanofiber-based PhC cavities and the efficient integration to the fiber networks, may open new possibilities for nanophotonic applications and quantum information science.

We present a protocol for fabricating 1-D photonic crystal cavities on subwavelength diameter silica fibers (optical nanofibers) using femtosecond laser-induced ablation.

Fabricação de 1-D cristal fotônico cavidade em um nanofibras com ablação induzida por laser femtosegundo

We present a protocol for fabricating 1-D Photonic Crystal (PhC) cavities on subwavelength-diameter tapered optical fibers, optical nanofibers, using ...

Fabrication of Polymer Microspheres for Optical Resonator and Laser Applications

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, interface precipitation, and mini-emulsion. In all methods, well-defined, micrometer-sized spheres are obtained from a self-assembling process in solution. The vapor diffusion method can result in spheres with the highest sphericity and surface smoothness, yet the types of the polymers able to form these spheres are limited. On the other hand, in the mini-emulsion method, microspheres can be made from various types of polymers, even from highly crystalline polymers with coplanar, &#960;-conjugated backbones. The photoluminescent (PL) properties from single isolated microspheres are unusual: the PL is confined inside the spheres, propagates at the circumference of the spheres via the total internal reflection at the polymer/air interface, and self-interferes to show sharp and periodic resonant PL lines. These resonating modes are so-called "whispering gallery modes" (WGMs). This work demonstrates how to measure WGM PL from single isolated spheres using the micro-photoluminescence (&#181;-PL) technique. In this technique, a focused laser beam irradiates a single microsphere, and the luminescence is detected by a spectrometer. A micromanipulation technique is then used to connect the microspheres one by one and to demonstrate the intersphere PL propagation and color conversion from coupled microspheres upon excitation at the perimeter of one sphere and detection of PL from the other microsphere. These techniques, &#181;-PL and micromanipulation, are useful for experiments on micro-optic application using polymer materials.

Protocols for the synthesis of microspheres from polymers, the manipulation of microspheres, and micro-photoluminescence measurements are presented.

Fabricação de Microsferas de Polímeros para Resonadores Ópticos e Aplicações Laser

This paper describes three methods of preparing fluorescent microspheres comprising &#960;-conjugated or non-conjugated polymers: vapor diffusion, ...

Scalable Solution-processed Fabrication Strategy for High-performance, Flexible, Transparent Electrodes with Embedded Metal Mesh

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a polymer film. This paper also presents a low-cost, vacuum-free fabrication method for this novel TE; the approach combines lithography, electroplating, and imprint transfer (LEIT) processing. The embedded nature of the EMTEs offers many advantages, such as high surface smoothness, which is essential for organic electronic device production; superior mechanical stability during bending; favorable resistance to chemicals and moisture; and strong adhesion with plastic film. LEIT fabrication features an electroplating process for vacuum-free metal deposition and is favorable for industrial mass production. Furthermore, LEIT allows for the fabrication of metal mesh with a high aspect ratio (i.e., thickness to linewidth), significantly enhancing its electrical conductance without adversely losing optical transmittance. We demonstrate several prototypes of flexible EMTEs, with sheet resistances lower than 1 &#937;/sq and transmittances greater than 90%, resulting in very high figures of merit (FoM) &#8211; up to 1.5 x 104 &#8211; which are amongst the best values in the published literature.

This protocol describes a solution-based fabrication strategy for high-performance, flexible, transparent electrodes with fully-embedded, thick metal mesh. Flexible transparent electrodes fabricated by this process demonstrate among the highest reported performances, including ultra-low sheet resistance, high optical transmittance, mechanical stability under bending, strong substrate adhesion, surface smoothness, and environmental stability.

Estratégia de fabricação processada e escalável para eletrodos flexíveis e transparentes de alto desempenho com malha metálica embutida

Here, the authors report the embedded metal-mesh transparent electrode (EMTE), a new transparent electrode (TE) with a metal mesh completely embedded in a ...

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

Fabricação de filmes de cor ultra-fino com altamente absorvente Media usando ângulo oblíquo deposição

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...

Production of Single Tracks of Ti-6Al-4V by Directed Energy Deposition to Determine the Layer Thickness for Multilayer Deposition

Directed Energy Deposition (DED), which is an additive manufacturing technique, involves the creation of a molten pool with a laser beam where metal powder is injected as particles. In general, this technique is employed to either fabricate or repair different components. In this technique, the final characteristics are affected by many factors. Indeed, one of the main tasks in building components by DED is the optimization of process parameters (such as laser power, laser speed, focus, etc.) which is usually carried out through an extensive experimental investigation. However, this sort of experiment is extremely lengthy and costly. Thus, in order to accelerate the optimization process, an investigation was conducted to develop a method based on the melt pool characterizations. In fact, in these experiments, single tracks of Ti-6Al-4V were deposited by a DED process with multiple combinations of laser power and laser speed. Surface morphology and dimensions of single tracks were analyzed, and geometrical characteristics of melt pools were evaluated after polishing and etching the cross-sections. Helpful information regarding the selection of optimal process parameters can be achieved by examining the melt pool features. These experiments are being extended to characterize the larger blocks with multiple layers. Indeed, this manuscript describes how it would be possible to quickly determine the layer thickness for the massive deposition, and avoid over or under-deposition according to the calculated energy density of the optimum parameters. Apart from the over or under-deposition, time and materials saving are the other great advantages of this approach in which the deposition of multilayer components can be started without any parameter optimization in terms of layer thickness.

In this research, a rapid method based on melt pool characterization is developed to estimate the layer thickness of Ti-6Al-4V components produced by directed energy deposition.

Produção de Single Tracks de Ti-6Al-4V pela deposição de energia dirigida para determinar a espessura de camada para deposição de várias camada

Directed Energy Deposition (DED), which is an additive manufacturing technique, involves the creation of a molten pool with a laser beam where metal ...