The financial support by DFG (German research foundation, project CZ 55/30-1) for parts of this work is gratefully acknowledged.

1. Montagem do Setup Experimental <ol><li> Preparando o lado proximal <ol><li> Colocar e fixar o laser fornecer um feixe de luz colimada - ou usar um laser de fibra-acoplado com óptica de colimação na faceta de saída da fibra. </li><li> Coloque o divisor de feixe de polarização (PBS) para dividir o feixe de laser para referência e feixe do objeto. Virar a orientação das placas de meia onda (HWP) rodando o HWP na sua rotação de montagem até que a energia de feixe de referência e feixe de objecto (no lado distal) é aproximadamente a mesma. Verifique isso colocando uma tela em ambos os de referência e feixe do objeto. Escolha da orientação do PBS, de forma que a polarização do feixe de referência se encaixa o modulador de luz espacial sensível à polarização (SLM). </li><li> Coloque um divisor de feixe (BS) para o feixe de referência para dividir o feixe de referência em dois feixes. Coloque os moduladores ópticos (OM) de tal forma que estes dois feixes provenientes de BS1 podem passar OM1 e OM2, respectivamente. &lt;/ Li&gt; <li> Combine os dois feixes que passam OM1 e OM2 em BS2 empregando dois espelhos. Ajuste os divisores de feixe e espelhos para que ambos os feixes são separados espacialmente. </li><li> alinhar cuidadosamente BS5 para assegurar que a direcção de incidência de ambas as vigas é perpendicular ao plano de pixel da SLM, ignorando BS3 e BS4 em primeiro lugar. Em primeiro lugar, nada é apresentado na SLM, isto é, actua como um espelho, até ao final da calibração (em todo o passo 2). </li><li> Ajustar a posição e a distância entre as duas lentes (L), que constitui um telescópio Kepler, a fim de obter uma imagem nítida do plano SLM na câmara complementar semicondutor de óxido metálico (CMOS). Assista a orientação correta de L1 e L2 (lados planos estão enfrentando uns aos outros) para minimizar aberrações. </li></ol></li><li> Preparação do lado distal <ol><li> Use BS7 para dividir o feixe do objeto em dois feixes e combiná-los em BS8 empregando dois espelhos. Mais uma vez, ajuste os divisores de feixe e mirrors de modo que ambos os feixes estão espacialmente separadas. </li><li> Desviar ambas as vigas usando BS9 para apontar-los para a objetiva do microscópio (OBJ). Focagem obj2 na extremidade distal da fibra multimodo (MMF). Verifique o foco observando o reflexo de volta do MMF empregando L3 e um dispositivo de câmara de carga acoplada (CCD). </li></ol></li><li> Conexão proximal e distal <ol><li> Colimar a luz do feixe do objeto sair do MMF empregando Obj1. </li><li> Dividir o feixe do objeto usando BS6, ignorar o polarizador linear (LP) em primeiro lugar. Combinar as duas vigas de objeto com as duas vigas de referência em BS3 e BS4 empregando um espelho. Ajustar os espelhos divisores de feixe e de modo que cada par de referência e feixe de objecto sobreposição na SLM, cruzando com um pequeno ângulo (inferior a 1 °). </li><li> Assegure-se que a potência de referência e o feixe de objecto são aproximadamente iguais, rodando a orientação do HWP, de acordo com o passo 1.1.2. </li><li> Verifique a interferência pattern (fora do eixo holograma) para a câmera CMOS e ajustar o ângulo de cruzamento em conformidade. Aumentar o ângulo, até que o espaçamento franja de interferência aproximadamente igual ao tamanho de dois pixels na câmara CMOS. </li><li> Ajustar a orientação do LP para coincidir com a polarização do objecto e feixe de referência, a fim de obter um máximo contraste do padrão de interferência na imagem da câmara CMOS, de modo que a imagem da câmara mostra franjas distintas. </li></ol></li></ol> 2. Calibração do Sistema <ol><li> Calibrar a relação de pixel entre SLM e CMOS <ol><li> Iluminar toda a SLM utilizando apenas um dos feixes de referência e bloquear a outra referência e objetos vigas. </li><li> Capturar uma imagem do SLM com a câmera CMOS. </li><li> Obter as coordenadas do canto superior esquerdo da SLM na imagem da câmara CMOS, por exemplo, usando o software de gráficos e o cursor do mouse no PC. Use essas coordenadas de pixel como o ponto de origemsobre a SLM. </li><li> Remova todos os blocos de feixe. </li></ol></li><li> Calibrar os caminhos de sinal <ol><li> Bloquear tanto de referência da viga 2 e objeto feixe 2. </li><li> Capturar uma imagem do holograma com a câmara CMOS. Avaliar a fase no holograma gravado usando o método espectro angular 19. Calcula-se a fase invertida na região correspondente do feixe 1. </li><li> Retirar os antigos blocos de feixe e agora bloquear tanto de referência da viga 1 e objeto feixe 1. </li><li> Capturar uma imagem do holograma com a câmara CMOS. Medir a fase no holograma gravada usando o método espectro angular novamente. Calcula-se a fase invertida na região correspondente da travessa 2. </li><li> Remova todos os blocos de feixe. </li></ol></li></ol> 3. transmitir os sinais <ol><li> Bloquear o feixe objeto. </li><li> Costurar as imagens de fase invertida calculados às regiões correspondentes do feixe 1 e 2 juntos e exibir otoda imagem na SLM, geralmente usando a porta de computação gráfica. </li><li> Comece a modulação dos sinais de entrada 1 e 2, ativando OM1 e OM2. </li><li> Observe os sinais de saída 1 e 2 na câmara CCD. </li></ol>

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The authors have nothing to disclose.

A montagem do dispositivo experimental (passo 1 no protocolo) requer um alinhamento completa dos componentes ópticos em relação uns aos outros. O aspecto mais importante é a incidência rectangular dos feixes de referência para o SLM, a fim de assegurar um elevado PBR. A fim de aumentar a configuração de mais de dois sinais transmitidos, pode ser utilizado divisores de feixe adicionais. Como uma alternativa, uma aplicação à base de fibras seria mais compacta e robusta permitindo qu...

A transmissão de sinais múltiplos de luz através de uma fibra multimodo (MMF) é evidente em comunicação de engenharia 1 e 2 biofotónica. Na engenharia de comunicações, acredita-se que a multiplexação por divisão de espaço (SDM) como uma solução viável para melhorar a capacidade de transmissão de fibras ópticas para aplicações de transferência de dados futuras que beneficiam de uma maior utilização do espaço limitado, em comparação com várias fibras monomodo 3. Em biophotonics, amostras biológicas são manipulados pela transmissão da luz através de um endoscópio MMF 4. Por exemplo, o dispositivo de controlo óptico independente de neurónios individuais usando endoscópios MMF é de interesse para Optogenetics, a fim de estudar as redes neuronais no cérebro 5. No entanto, a luz projetada sobre a faceta de entrada MMF está sujeito a distorção devido à mistura de modo e dispersão durante a propagação para o Output faceta do MMF. Como resultado, a propagação da luz é alterada, o que torna a transmissão de sinal desafiador. Wavefront moldar métodos 6, 7 são aplicados na dispersão mídia usando moduladores de luz espacial (SLM) e permitir a compensação para a distorção devido à dispersão durante a propagação da luz 8. Existem abordagens iterativos que otimizam a saída usando uma realimentação óptica 9. Estas abordagens são bastante demorado devido à necessidade de numerosas iterações e o elevado grau de liberdade, correspondendo a um grande número de elementos de modulador. Outra abordagem é para determinar completamente a distorção dentro do MMF descrito por sua matriz de transmissão 10. Se o número de modos a serem transmitidos é grande, este irá ser demorado bem. Em contraste, a conjugação de fase digital óptico (DOPC) é considerado como sendorápido e vantajoso aqui, uma vez que apenas alguns pontos focais têm que ser gerado no faceta do MMF saída. Abordagens conjugação de fase também foram demonstradas para a focagem de imagem ou através do tecido biológico 12, 13, 14. Até agora, DOPC foi empregue para um único sinal de tempo de apenas 15, 16, e foi aplicada para a transmissão de luz através de um MMF 17. Uma abordagem DOPC para vários sinais independentes não foi realizado. Desenvolvemos um método de DOPC melhorada proporcionando o transporte independente de sinais de luz múltiplas utilizando frente de onda individuais que constituem para cada sinal que emprega uma única fase apenas SLM 18. Para este objectivo, o SLM é segmentado em regiões, um para cada sinal a ser transmitido. A configuração experimental proposto é mostrado na Figura 1, Onde uma calibração é realizado em a), antes da transmissão efectiva acontece em b). <img alt="figura 1" src="/files/ftp_upload/55407/55407fig1.jpg" /> Figura 1: Instalação experimental. BS = divisor de feixe, CCD = charge-coupled device, OM = modulador óptico, CMOS = complementar semicondutor de óxido de metal, HWP = meia placa onda, L = lente, LP = polarizador linear, MMF = fibra multimodo, objetiva obj = microscópio, PBS = polarização divisor de feixe, SLM = modulador de luz espacial (fase única) - apenas vigas relevantes para (a) a calibração e (b) a transmissão são representados <a href="http://ecsource.jove.com/files/ftp_upload/55407/55407fig1large.jpg" target="_blank">por favor clique aqui para ver uma versão maior desta figura.</a>

<table><tbody><tr><td>spatial light modulator</td><td>Holoeye</td><td>PLUTO-VIS-016</td><td></td></tr><tr><td>CMOS camera</td><td>Mikrotron</td><td>MC4082</td><td></td></tr><tr><td>diode-pumped solid state laser</td><td>Laser Quantum</td><td>torus 532</td><td></td></tr><tr><td>CCD camera</td><td>IDS</td><td>U3-3482LE-M CMOS</td><td>camera; suitable as well</td></tr><tr><td>lens 1</td><td>Qioptiq</td><td>G063204000</td><td></td></tr><tr><td>lens 2</td><td>Qioptiq</td><td>G063203000</td><td></td></tr><tr><td>lens 3</td><td>Thorlabs</td><td>AC508-180-A-ML</td><td></td></tr><tr><td>multimode fiber</td><td>Thorlabs</td><td>M14L02</td><td></td></tr><tr><td>beam splitters</td><td>Thorlabs</td><td>BS013</td><td>9x</td></tr><tr><td>polarizing beam splitters</td><td>Thorlabs</td><td>PBS251</td><td></td></tr><tr><td>mirrors</td><td>Thorlabs</td><td>PF10-03-P01</td><td>5x</td></tr><tr><td>microscope objectives</td><td>Thorlabs</td><td>RMS20X</td><td>2x</td></tr><tr><td>half wave plates</td><td>Thorlabs</td><td>WPH10M-532</td><td>2x</td></tr><tr><td>linear polarizer</td><td>Thorlabs</td><td>LPVISB050-MP2</td><td></td></tr><tr><td>optical modulators</td><td>Thorlabs</td><td>MC2000B-EC</td><td>2x</td></tr><tr><td>linear and rotation stage for CMOS camera</td><td>Thorlabs</td><td>XYR1/M</td><td></td></tr><tr><td>fiber connector</td><td>Thorlabs</td><td>S120-SMA</td><td>2x</td></tr><tr><td>reducing ring for microscope objectives</td><td>Qioptiq</td><td>G061621000</td><td>2x</td></tr><tr><td>xy adjustment for objective adapters</td><td>Qioptiq</td><td>G061025000</td><td>2x</td></tr><tr><td>z translation mount for fiber adapter</td><td>Thorlabs</td><td>SM1Z</td><td>2x</td></tr><tr><td>rods for fiber alignment to objectives</td><td>Qioptiq</td><td>G061210000</td><td>8x</td></tr><tr><td>mounts for lenses 1 and 2 plus two phantom mounts</td><td>Qioptiq</td><td>G061047000</td><td>4x</td></tr><tr><td>rail carriers for objective and lens mounts</td><td>Qioptiq</td><td>G061372000</td><td>6x</td></tr><tr><td>rail for rail carriers</td><td>Qioptiq</td><td>G061359000</td><td>2x</td></tr><tr><td>adapter for CCD camera to 1 post</td><td></td><td></td><td>in-house</td></tr><tr><td>adapter for laser to 4 posts</td><td></td><td></td><td>in-house</td></tr><tr><td>mount for lens 3</td><td>Thorlabs</td><td>LMR2/M</td><td></td></tr><tr><td>mounts for half wave plates</td><td>Thorlabs</td><td>RSP1D/M</td><td>2</td></tr><tr><td>mounts for mirrors</td><td>Thorlabs</td><td>KM100</td><td>5x</td></tr><tr><td>mount for linear polarizer</td><td>Thorlabs</td><td>RSP05/M</td><td></td></tr><tr><td>mounts for beam splitters and SLM</td><td>Thorlabs</td><td>KM100PM/M</td><td>11x</td></tr><tr><td>clamping arms for beam splitters and SLM</td><td>Thorlabs</td><td>PM4/M</td><td>11x</td></tr><tr><td>posts for mounts, rail carriers and adapters</td><td>Thorlabs</td><td>TR75/M</td><td>29x</td></tr><tr><td>holders for posts</td><td>Thorlabs</td><td>PH50/M</td><td>29x</td></tr><tr><td>pedestals for holders</td><td>Thorlabs</td><td>BE1/M</td><td>29x</td></tr><tr><td>clamping forks for pedestals</td><td>Thorlabs</td><td>CF125</td><td>29x</td></tr></tbody></table>

transmission of multiple signals through an optical fiber using wavefront shaping

A transmissão de sinais ópticos múltiplos independentes, através de uma fibra multimodo é realizado utilizando moldagem de frente de onda, a fim de compensar a distorção durante a propagação da luz no interior da fibra. Nossa metodologia é baseada na conjugação de fase digital óptico empregando apenas um único modulador de luz espacial, onde a frente de onda óptico é modulado individualmente em diferentes regiões do modulador, uma região por sinal luminoso. abordagens de conjugação de fase óptica digitais são considerados para ser mais rápido do que outras abordagens de frente de onda moldar, onde (por exemplo) é realizada uma determinação completa do comportamento de propagação da onda da fibra. Em contraste, a abordagem apresentada é rápida e eficiente uma vez que requer apenas uma calibração por cada sinal de luz. O método proposto é potencialmente adequado para a multiplexação por divisão espacial em engenharia de comunicações. Outros campos de aplicação são a entrega de luz endoscópica em biophotonics, especialmente em optogenetics, onde as células individuais no tecido biológico tem que ser iluminada seletivamente com alta resolução espacial e temporal.

<html> Sinais de saída típica no lado distal da fibra longa de 2 m estão descritos na Figura 2. Note-se que o ponto focal desejado (pico) é acompanhado por um padrão de manchas indesejadas (background), o que é devido à imperfeição da DOPC como uma questão de princípio. O correspondente rácio de pico-a-fundo (PBR) ascende a 53 (apenas um sinal 1 é &#39;on&#39;), 36 (apenas o sinal 2 é &#39;ligado&#39;) e 20 (ambos os sinais 1 e 2 são &#39;on&#39;) aqui, res...

Watch this Scientific Journal Video about Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping at JoVE.com

Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping

We demonstrate the transmission of multiple independent signals through a multimode fiber using wavefront shaping employing a single spatial light modulator. By modulating the wavefront for each signal individually, spatially separated foci are transmitted. Potential applications are multiplexed data transfer in communications engineering and endoscopic light delivery in biophotonics.

Transmissão de múltiplos sinais através de uma fibra óptica Usando Wavefront Shaping

The transmission of multiple independent optical signals through a multimode fiber is accomplished using wavefront shaping in order to compensate for the ...

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9.8K visualizações.  TU Dresden. We demonstrate the transmission of multiple independent signals through a multimode fiber using wavefront shaping employing a single spatial light modulator. By modulating the wavefront for each signal individually, spatially separated foci are transmitted. Potential applications are multiplexed data transfer in communications engineering and endoscopic light delivery in biophotonics.

Vídeo: Transmission of Multiple Signals through an Optical Fiber Using Wavefront Shaping

Quasi-light Storage for Optical Data Packets

Today's telecommunication is based on optical packets which transmit the information in optical fiber networks around the world. Currently, the processing of the signals is done in the electrical domain. Direct storage in the optical domain would avoid the transfer of the packets to the electrical and back to the optical domain in every network node and, therefore, increase the speed and possibly reduce the energy consumption of telecommunications. However, light consists of photons which propagate with the speed of light in vacuum. Thus, the storage of light is a big challenge. There exist some methods to slow down the speed of the light, or to store it in excitations of a medium. However, these methods cannot be used for the storage of optical data packets used in telecommunications networks. Here we show how the time-frequency-coherence, which holds for every signal and therefore for optical packets as well, can be exploited to build an optical memory. We will review the background and show in detail and through examples, how a frequency comb can be used for the copying of an optical packet which enters the memory. One of these time domain copies is then extracted from the memory by a time domain switch. We will show this method for intensity as well as for phase modulated signals.

The article describes a procedure to store optical data packets with an arbitrary modulation, wavelength, and data rate. These packets are the basis of modern telecommunications.

Armazenamento Quasi-luz para os pacotes de dados ópticos

Today's telecommunication is based on optical packets which transmit the information in optical fiber networks around the world. Currently, the processing ...

Engenharia

Fabrication and Characterization of Disordered Polymer Optical Fibers for Transverse Anderson Localization of Light

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed polymer optical fiber is composed of 80,000 strands of poly (methyl methacrylate) (PMMA) and polystyrene (PS) that are randomly mixed and drawn into a square cross section optical fiber with a side width of 250 &mu;m. Initially, each strand is 200 &mu;m in diameter and 8-inches long. During the mixing process of the original fiber strands, the fibers cross over each other; however, a large draw ratio guarantees that the refractive index profile is invariant along the length of the fiber for several tens of centimeters. The large refractive index difference of 0.1 between the disordered sites results in a small localized beam radius that is comparable to the beam radius of conventional optical fibers. The input light is launched from a standard single mode optical fiber using the butt-coupling method and the near-field output beam from the disordered fiber is imaged using a 40X objective and a CCD camera. The output beam diameter agrees well with the expected results from the numerical simulations. The disordered optical fiber presented in this work is the first device-level implementation of 2D Anderson localization, and can potentially be used for image transport and short-haul optical communication systems.

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. This microstructured fiber can transport a small localized beam with a radius that is comparable to the beam radius of conventional optical fibers.

Fabricação e caracterização de polímeros desordenados fibras ópticas para Transverse Anderson localização da Luz

We develop and characterize a disordered polymer optical fiber that uses transverse Anderson localization as a novel waveguiding mechanism. The developed ...

Writing Bragg Gratings in Multicore Fibers

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong suppression at a single wavelength requires that all cores have matching transmission profiles. These gratings cannot be inscribed using the same method as for single-core fibers because the curved surface of the cladding acts as a lens, focusing the incoming UV laser beam and causing variations in exposure between cores. Therefore we use an additional optical element to ensure that the beam shape does not change while passing through the cross-section of the multicore fiber. This consists of a glass capillary tube which has been polished flat on one side, which is then placed over the section of the fiber to be inscribed. The laser beam enters the fiber through the flat surface of the capillary tube and hence maintains its original dimensions. This paper demonstrates the improvements in core-to-core uniformity for a 7-core fiber using this method. The technique can be generalized to larger multicore fibers.

We describe a technique for inscribing identical fiber Bragg gratings into each core of a multicore fiber. This is achieved by introducing an additional surface into the optical path to mitigate lensing by the curved surface of the fiber cladding.

Escrevendo redes de Bragg em fibras Multicore

Fiber Bragg gratings in multicore fibers can be used as compact and robust filters in astronomical and other research and commercial applications. Strong ...

Generation and Coherent Control of Pulsed Quantum Frequency Combs

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional states on-chip in a practical way have remained elusive due to the increasing complexity of the quantum circuitry needed to prepare and process such states. Here, we outline how high-dimensional, frequency-bin entangled, two-photon states can be generated at a stable, high generation rate by using a nested-cavity, actively mode-locked excitation of a nonlinear micro-cavity. This technique is used to produce pulsed quantum frequency combs. Moreover, we present how the quantum states can be coherently manipulated using standard telecommunications components such as programmable filters and electro-optic modulators. In particular, we show in detail how to accomplish state characterization measurements such as density matrix reconstruction, coincidence detection, and single photon spectrum determination. The presented methods form an accessible, reconfigurable, and scalable foundation for complex high-dimensional state preparation and manipulation protocols in the frequency domain.

A protocol is presented for the practical generation and coherent manipulation of high-dimensional frequency-bin entangled photon states using integrated micro-cavities and standard telecommunications components, respectively.

Geração e controle coerente de pentes de frequência pulsada Quantum

We present a method for the generation and coherent manipulation of pulsed quantum frequency combs. Until now, methods of preparing high-dimensional ...

High-Throughput Total Internal Reflection Fluorescence and Direct Stochastic Optical Reconstruction Microscopy Using a Photonic Chip

Total internal reflection fluorescence (TIRF) is commonly used in single molecule localization based super-resolution microscopy as it gives enhanced contrast due to optical sectioning. The conventional approach is to use high numerical aperture microscope TIRF objectives for both excitation and collection, severely limiting the field of view and throughput. We present a novel approach to generating TIRF excitation for imaging with optical waveguides, called chip-based nanoscopy. The aim of this protocol is to demonstrate how chip-based imaging is performed in an already built setup. The main advantage of chip-based nanoscopy is that the excitation and collection pathways are decoupled. Imaging can then be done with a low magnification lens, resulting in large field of view TIRF images, at the price of a small reduction in resolution. Liver sinusoidal endothelial cells (LSECs) were imaged using direct stochastic optical reconstruction microscopy (dSTORM), showing a resolution comparable to traditional super-resolution microscopes. In addition, we demonstrate the high-throughput capabilities by imaging a 500 &#181;m x 500 &#181;m region with a low magnification lens, providing a resolution of 76 nm. Through its compact character, chip-based imaging can be retrofitted into most common microscopes and can be combined with other on-chip optical techniques, such as on-chip sensing, spectroscopy, optical trapping, etc. The technique is thus ideally suited for high throughput 2D super-resolution imaging, but also offers great opportunities for multi-modal analysis.

Chip-based super-resolution optical microscopy is a novel approach to fluorescence microscopy and offers advantages in cost effectiveness and throughput. Here, the protocols for chip preparation and imaging are shown for TIRF microscopy and localization-based super-resolution microscopy.

Fluorescência de reflexão interna total de alta taxa de transferência e microscopia de reconstrução óptica estocástica direta usando um chip fotônico

Total internal reflection fluorescence (TIRF) is commonly used in single molecule localization based super-resolution microscopy as it gives enhanced ...

Bioquímica

Shaping the Amplitude and Phase of Laser Beams by Using a Phase-only Spatial Light Modulator

The aim of this article is to visually demonstrate the utilization of an interferometric method for encoding complex fields associated with coherent laser radiation. The method is based on the coherent sum of two uniform waves, previously encoded into a phase-only spatial light modulator (SLM) by spatial multiplexing of their phases. Here, the interference process is carried out by spatial filtering of light frequencies at the Fourier plane of certain imaging system. The correct implementation of this method allows arbitrary phase and amplitude information to be retrieved at the output of the optical system.
It is an on-axis, rather than off-axis encoding technique, with a direct processing algorithm (not an iterative loop), and free from coherent noise (speckle). The complex field can be exactly retrieved at the output of the optical system, except for some loss of resolution due to the frequency filtering process. The main limitation of the method might come from the inability to operate at frequency rates higher than the refresh rate of the SLM. Applications include, but are not limited to, linear and non-linear microscopy, beam shaping, or laser micro-processing of material surfaces.

We show how to encode the complex field of laser beams by using a single phase element. A common-path interferometer is employed to mix the phase information displayed into a phase-only spatial light modulator to finally retrieve the desired complex field pattern at the output of an optical imaging system.

Moldar a Amplitude e a fase dos feixes de Laser, usando um modulador de luz somente fase espacial

The aim of this article is to visually demonstrate the utilization of an interferometric method for encoding complex fields associated with coherent laser ...

Low-cost Custom Fabrication and Mode-locked Operation of an All-normal-dispersion Femtosecond Fiber Laser for Multiphoton Microscopy

A protocol is presented to build a custom low-cost yet high-performance femtosecond (fs) fiber laser. This all-normal-dispersion (ANDi) ytterbium-doped fiber laser is built completely using commercially available parts, including $8,000 in fiber optic and pump laser components, plus $4,800 in standard optical components and extra-cavity accessories. Researchers new to fiber optic device fabrication may also consider investing in basic fiber splicing and laser pulse characterization equipment (~$63,000). Important for optimal laser operation, methods to verify true versus apparent (partial or noise-like) mode-locked performance are presented. This system achieves 70 fs pulse duration with a center wavelength of approximately 1,070 nm and a pulse repetition rate of 31 MHz. This fiber laser exhibits the peak performance that may be obtained for an easily assembled fiber laser system, which makes this design ideal for research laboratories aiming to develop compact and portable fs laser technologies that enable new implementations of clinical multiphoton microscopy and fs surgery.

A method is presented to build a custom low-cost, mode-locked femtosecond fiber laser for potential applications in multiphoton microscopy, endoscopy, and photomedicine. This laser is built using commercially available parts and basic splicing techniques.

Fabricação personalizada de baixo custo e operação bloqueada pelo modo de um laser de fibra femtosecond de dispersão normal para microscopia multifoton

A protocol is presented to build a custom low-cost yet high-performance femtosecond (fs) fiber laser. This all-normal-dispersion (ANDi) ytterbium-doped ...

Characterization of SiN Integrated Optical Phased Arrays on a Wafer-Scale Test Station

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for moving mechanical parts. This technology is particularly useful for beam steering applications. Here, we focus on OPAs integrated into SiN photonic circuits for a wavelength in the near infrared. A characterization method of such circuits is presented, which allows the output beam of integrated OPAs to be shaped and steered. Furthermore, using a wafer-scale characterization setup, several devices can easily be tested across multiple dies on a wafer. In this way, fabrication variations can be studied, and high-performance devices identified. Typical images of OPA beams are shown, including beams emitted from OPAs with and without a uniform waveguide length, and with varying numbers of channels. In addition, the evolution of output beams during the phase optimization process and beam steering in two dimensions is presented. Finally, a study of the variation in the beam divergence of identical devices is performed with respect to their position on the wafer.

Here, we describe the operation of a SiN integrated photonic circuit containing optical phased arrays. The circuits are used to emit low divergence laser beams in the near infrared and steer them in two dimensions.

Caracterização de arrays em fases ópticas integradas siN em uma estação de teste em escala de wafer

Optical phased arrays (OPAs) can produce low-divergence laser beams and can be used to control the emission angle electronically without the need for ...

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor fluorescence detection in droplet microfluidics typically involves bulky and complex epifluorescence microscope-based detection systems. Here we describe a compact and modular multicolor detection scheme that utilizes an array of optical fibers to temporally encode multicolor data collected by a single photodetector.

Multicolor detecção de fluorescência para Gota microfluídica Utilizando Fibras Ópticas

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as ...

Bioengenharia

Optimizing Brillouin Optical Time-Domain Analyzers Based on Gain Spectrum Engineering

Demonstrated is a unique method for sensing performance enhancement in Brillouin optical time-domain analyzers (BOTDA). A Brillouin gain spectrum (BGS) is superimposed with two symmetric Brillouin loss spectra (BLS). This leads to a complex engineered spectrum shape that is more resistant to the sensing system noise. Instead of only one pump and probe interaction as in the conventional BOTDA setup, three optical probe waves are exploited, with one probe located in the BGS and the other two symmetrically in the BLS. Due to the resistance and insensitivity of the engineered spectrum shape to the noise, the sensing performance is enhanced by 60% and the measurand resolution is doubled.

A protocol for Brillouin optical time-domain analyzers based on gain spectrum engineering is presented. Enhancements in the sensing performance, including sensing range and measurand resolution are achieved and the excess Brillouin intensity noise is studied. The protocol introduces a new way to enhance distributed Brillouin sensing performance.

Demonstrated is a unique method for sensing performance enhancement in Brillouin optical time-domain analyzers (BOTDA). A Brillouin gain spectrum (BGS) is ...