Name: characterization of anisotropic leaky mode modulators for holovideo
Uploaded: 2016-03-19T15:00:00.000+00:00
Duration: 9 min 36 s
Description: Watch this Scientific Journal Video about Characterization of Anisotropic Leaky Mode Modulators for Holovideo at JoVE.com

Los autores agradecen el apoyo financiero del Air Force Research Laboratory contrato FA8650-14-C-6571 y desde DAQRI LLC.

<ol>
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SPIE. 1932, 298-311 (1993).</li><li>Ito, K., Kawamoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+optical+deflector+using+collinear+acoustooptic+coupling+fabricated+on+proton-exchanged+LiNbO+3.">An optical deflector using collinear acoustooptic coupling fabricated on proton-exchanged LiNbO 3.</a> Jpn. J. Appl. Phys. 37 (9R), 4858 (1998).</li><li>Smalley, D., Smithwick, Q., Barabas, J., Jolly, S., DellaSilva, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Holovideo+for+everyone:+a+low-cost+holovideo+monitor.">Holovideo for everyone: a low-cost holovideo monitor.</a> J Phys Conf Ser. 415 (1), 012055 (2013).</li><li>McClaughlin, S., Leach, C., Henrie, A., Smalley, D., Jolly, S., Bove, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Frequency+Division+of+Color+for+Holovideo+Displays+using+Anisotropic+Leaky+Mode+Couplers.">Frequency Division of Color for Holovideo Displays using Anisotropic Leaky Mode Couplers.</a> Optical Society of America, 2015. , (2015).</li><li>McLaughlin, S., Leach, C., Henrie, A., Smalley, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimized+guided-to-leaky-mode+device+for+graphics+processing+unit+controlled+frequency+division+of+color.">Optimized guided-to-leaky-mode device for graphics processing unit controlled frequency division of color.</a> Appl. Opt. 54 (12), 3732-3736 (2015).</li><li>Jackel, J., Rice, C., Veselka, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proton+exchange+for+high-index+waveguides+in+LiNbO3.">Proton exchange for high-index waveguides in LiNbO3.</a> Appl. Phys. Lett. 41 (7), 607-608 (1982).</li><li>Wong, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Properties of lithium niobate. , (2002).</li><li>Tien, P., Ulrich, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theory+of+prism-film+coupler+and+thin-film+light+guides.">Theory of prism-film coupler and thin-film light guides.</a> JOSA. 60 (10), 1325-1337 (1970).</li><li>Tsai, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Guided-wave acousto-optics: interactions, devices, and applications. , (1990).</li><li>Proklov, V., Korablev, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multichannel+waveguide+devices+using+collinear+acousto-optic+interaction.">Multichannel waveguide devices using collinear acousto-optic interaction.</a> Proc. SPIE. 1932, 298-311 (1993).</li><li>Li, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Circuit Design. , (2012).</li><li>Lawrence, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+mechanics+of+spin+coating+of+polymer+films.">The mechanics of spin coating of polymer films.</a> Phys. Fluids. 31 (10), 2786-2795 (1988).</li><li>Fontana, R., Katine, J., Rooks, M., Viswanathan, R., Lille, J., MacDonald, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=E-beam+writing:+a+next-generation+lithography+approach+for+thin-film+head+critical+features.">E-beam writing: a next-generation lithography approach for thin-film head critical features.</a> IEEE Trans. Magn. 38 (1), 95-100 (2002).</li><li>Robertson, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Substrate Surface Preparation Handbook. , (2011).</li><li>Monneret, S., Flory, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=M-lines+technique:+prism+coupling+measurement+and+discussion+of+accuracy+for+homogeneous+waveguides.">M-lines technique: prism coupling measurement and discussion of accuracy for homogeneous waveguides.</a> J Opt A-Pure Appl Op. 2 (3), 188 (2000).</li></ol>

Los autores no tienen nada que revelar.

El diseño de cada dispositivo tiene dos pasos críticos, intercambio de protones y de desarrollo de la LOR. De los dos, el tiempo de intercambio de protones determina la profundidad de la guía de ondas, que a su vez determina el número de transiciones guiada a fugas modo, el ancho de banda de frecuencia controlable, y todos los parámetros clave de diseño para cada color de la luz. se desean dos modos guiados en rojo. Si más existe, entonces se sacrifica ancho de banda. Si existen menos entonces no guiado a modo de...

La mayoría de las tecnologías de pantallas holográficas, tales como válvulas de luz pixelada así como los dispositivos MEMS y moduladores acústico-ópticos de onda mayor, son demasiado complejos para permitir una amplia participación en su desarrollo. Moduladores pixelados, especialmente aquellos con capas de filtro y planos traseros activas pueden requerir docenas de pasos de modelado para construir 5 y puede ser limitado por fan-out 6. Cuanto mayor es el número de patrones pasos cuanto mayor es la complejidad del dispositivo, y cuanto más apretado el protocolo de fabricación debe ser lograr un rendimiento razonable dispositivo 7. Moduladores acústico-ópticos de onda mayor no se prestan a la oblea procesos basados ​​8,9. Anisotrópicas modo que gotea moduladores, sin embargo, requieren sólo dos pasos de modelado para fabricar y utilizar técnicas de microfabricación relativamente estándar 10,11. La accesibilidad de estos procesos hacen posible que cualquier institución a instalaciones de fabricación modestos para participar en el desarrollo de hLa tecnología de visualización de vídeo ológrafo 12. La simplicidad de la fabricación del dispositivo puede ser seductora, sin embargo, como el correcto funcionamiento de los dispositivos es fuertemente dependiente de las guías de ondas que deben ser cuidadosamente medido y ajustado para conseguir las características deseadas del dispositivo. Por ejemplo, si la guía de onda es demasiado profundo, ancho de banda operativo del dispositivo se reducirá 13. Si la guía de onda es demasiado bajo, el dispositivo no puede trabajar para iluminación roja. Si la guía de ondas es recocido demasiado largo, la forma del perfil de profundidad de la guía de ondas será distorsionada, y las transiciones de color rojo, verde y azul no puede sentarse adyacente en el dominio de la frecuencia 14. En este trabajo los autores presentan las herramientas y técnicas para realizar esta caracterización. El modulador de modo que gotea se compone de un protón intercambió guía de ondas indiffused en la superficie de un piezoeléctrico, X-Cut sustrato de niobato de litio 15,16. En un extremode la guía de ondas es un transductor interdigital de aluminio, véase la figura 1. La luz se introduce en la guía de ondas usando un acoplador de prisma 17. El transductor entonces lanza ondas acústicas que interactúan contralinearly con la luz en la guía de ondas a lo largo del eje y la superficie. Esta interacción parejas guiadas luz en un modo de fugas que se escapa de la guía de ondas en la masa y, finalmente, sale del sustrato desde el borde de la cara 18,19. Esta interacción también gira la polarización de la luz guiada TE polarizado de luz polarizada TM modo de fugas. El patrón de ondas acústicas de superficie es el holograma, y ​​es capaz de escanear y la configuración de la luz de salida para formar una imagen holográfica. La guía de onda es creada por intercambio de protones. En primer lugar, el aluminio se deposita sobre el sustrato. A continuación, el aluminio es el modelo foto-litografía y grabado para exponer regiones del sustrato a ser canales de guía de ondas. El aluminio restante actúa como un discomáscara. El sustrato se sumerge en una masa fundida de ácido benzoico que altera el índice de superficie en las regiones expuestas. El dispositivo se retira, se limpia y recocida en un horno de mufla. La profundidad final de la guía de onda determina el número de transiciones de modo que gotean. La profundidad de la guía de ondas también determina la frecuencia de cada transiciones guiadas a modo para cada color 4. Los transductores de aluminio se forman por el despegue. Después se forman las guías de ondas, un E-beam resistir se hila sobre el sustrato. Un transductor interdigital se modela con un haz de electrones para formar un transductor modulada pulsada diseñado para responder a la banda de 200 MHz responsable de controlar el color en los dispositivos de guía de ondas. El período de dedo se determina por Λƒ = v donde, Λ, es el período de dedo, v, es la velocidad del sonido en el sustrato y, ƒ, es la frecuencia de radio (RF). El transductor tendrá una impedancia que debe ser igualada a 75 ohmios para un funcionamiento eficiente 20. &lt;clase p = &quot;jove_content&quot;&gt; El guiado a la interacción con fugas modo se produce a diferentes frecuencias para diferentes longitudes de onda de luz de iluminación y como resultado la luz roja, verde y azul puede ser controlado en el dominio de la frecuencia. El patrón de onda acústica de superficie es generada por una señal de RF enviado al transductor interdigital. La RF de la señal de entrada se traducen en frecuencias espaciales en el patrón de onda acústica de superficie. La guía de ondas puede ser fabricado de manera que las señales de baja frecuencia de control del barrido angular y la amplitud de la luz roja, mientras que las frecuencias medias de control de luz verde y altas frecuencias de control de luz azul. Los autores han identificado un conjunto de parámetros de guía de ondas que permiten a los tres de estas interacciones deberán estar separados y adyacentes en el dominio de la frecuencia para que los tres colores se pueden controlar con una sola señal de 200 MHz, que es el ancho de banda máximo de unidades de procesamiento gráfico de los productos básicos ( GPU). Haciendo coincidir el ancho de banda de un canal de GPUa la de un modulador de modo que gotea, el sistema se vuelve completamente paralelo y altamente escalable. Mediante la adición de pares emparejados de ancho de banda de las GPU y los canales de modo modulador con fugas, se puede construir pantallas holográficas de tamaño arbitrario. Después de crear el dispositivo, se caracteriza cuidadosamente para verificar que las frecuencias para transición de modo guiado a fugas son apropiados para el control de frecuencia de color. En primer lugar, la ubicación de los modos guiados están determinados por un acoplador de prisma comercial para confirmar que la guía de ondas tiene la profundidad apropiada y el número correcto de modos guiados. Entonces, después de que los dispositivos están montados y empaquetados, se colocan en un acoplador de prisma costumbre que los mapas de las frecuencias de entrada de la luz de salida escaneada. Los datos resultantes da la respuesta de frecuencia de entrada y salida de la respuesta angular para la luz roja, verde y azul para el dispositivo que desea probar. Si el dispositivo ha sido fabricado correctamente, la respuesta del dispositivo de entrada se separa enla frecuencia y la respuesta de salida serán solapamiento en ángulo. Cuando esto se confirma, el dispositivo está listo para su uso en una pantalla de vídeo holográfico. Las primeras mediciones se llevan a cabo antes de que el dispositivo ha sido empaquetado. La profundidad de la guía de onda está determinada por un acoplador de prisma comercial. Esto se puede lograr con una sola longitud de onda de iluminación (típicamente 632 nm rojo) pero los autores han modificado su acoplador de prisma comercial para permitir que reúnen información del modo para la luz roja, verde y azul. Después de envasado, el dispositivo se somete a una segunda medición en un acoplador de prisma de encargo que registra la luz de salida desviada como una función de RF de entrada. Una descripción detallada de estas mediciones sigue. también se dan pasos de fabricación.

<table><tbody><tr><td>X-Cut Lithium Niobate</td><td>Gooch and Housego</td><td>99-00630-01</td><td>Lithium Niobate 3&amp;Prime; Diameter X-CUT Wafer 1&amp;nbsp;mm Polish/Polish</td></tr><tr><td>Positive Photo Resist 1</td><td>EMD Performance Materials</td><td>AZ 3330 F Photoresist</td><td>Used in the creation of the proton exchange mask</td></tr><tr><td>Photoresist Developer</td><td>EMD Performance Materials</td><td>AZ MIF 300</td><td>Develops AZ3330 and LOR 3A</td></tr><tr><td>Aluminium</td><td>International Advanced Materials</td><td>AL13</td><td>99.999% pure</td></tr><tr><td>Aluminium Etch</td><td>Transene</td><td>Type A Aluminum Etchant</td><td></td></tr><tr><td>Benzoic Acid</td><td>Sigma Aldrich</td><td>109479-500G</td><td>99% pure</td></tr><tr><td>Acetone</td><td>Fisher Chemical</td><td>UN1009</td><td></td></tr><tr><td>IPA</td><td>Fisher Chemical</td><td>UN1219</td><td>99.5% pure isopropyl alcohol</td></tr><tr><td>Acidic Piranha etch</td><td>Cyantek Corperation</td><td>Nanostrip</td><td></td></tr><tr><td>Under Layer Resist</td><td>Micro Chem</td><td>LOR 3A</td><td>Bottom layer used for liftoff</td></tr><tr><td>Positive Photo Resist</td><td>Micro Chem</td><td>950 PMMA A9</td><td>Top layer used for liftoff</td></tr><tr><td>Anisole</td><td>Micro Chem</td><td>A Thinner</td><td></td></tr><tr><td>Conductive polymer aqueous solution</td><td>Mitsubishi Rayon Company</td><td>AquaSAVE</td><td></td></tr><tr><td>MIBK (4-methyl-2-pentanone)</td><td>Sigma Aldrich</td><td>360511</td><td>Develops PMMA</td></tr><tr><td>NMP (1-methyl-2-pyrrolidone)</td><td>Sigma Aldrich</td><td>328634</td><td>Used for liftoff</td></tr><tr><td>E-beam Evaporator&amp;nbsp;</td><td>Denton Vacuum&amp;nbsp;</td><td>Integrity 20</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Thin Film Spinner</td><td>Laurell Technologies Corporation</td><td>WS-400A-6NPP-LITE</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Mask Aligner&amp;nbsp;</td><td>Karl Suss America Inc.</td><td>MA 150 CC</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Automatic Dicing Saw&amp;nbsp;</td><td>Disco Corperation</td><td>Disco Dad 320</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Muffle Furnace</td><td>Thermo Scientific</td><td>FB1415M</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Electron Microscope</td><td>FEI</td><td>XL30 ESEM</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Dehydration Oven</td><td>Lab-Line Instruments&amp;nbsp;</td><td>Ultra-Clean 100&amp;nbsp; (3497M-3)</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Hot Plate</td><td>Thermo Scientific</td><td>SP131325</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Polisher</td><td>Ultra Tec Mfg., Inc.</td><td>Ultrapol End &amp;amp; Edge Polisher</td><td>Any equivalent equipment would suffice.</td></tr><tr><td>Class IIIb 12&amp;nbsp;V RBG Lasers: Wavelengths (nm): 638, 532, and 445</td><td></td><td></td><td>Bought second-hand. Probably pulled from a laser projector. Any equivalent equipment would suffice.</td></tr><tr><td>Signal Generator</td><td>Agilent</td><td>8648D</td><td>Now found at Keysight. Obsolete. Any equivalent equipment would suffice. Needed Frequency sweep 9 kHz-1,000 MHz.</td></tr><tr><td>Signal Amplifier</td><td>Mini-Circuits</td><td>TB-17</td><td>Necessary only to overcome the limitations of the signal generator.</td></tr><tr><td>Power Meter Controller</td><td>ThorLabs</td><td>PM100D</td><td>With power meter model S130C. Any equivalent equipment would suffice. Needed sensitivity 500&amp;nbsp;pW.</td></tr><tr><td>Linear Actuator Controller</td><td>Newport</td><td>ESP7000</td><td>With linear actuator model MFN25PP. Any equivalent equipment would suffice. Needs 0.1&amp;nbsp;mm accuracy.</td></tr><tr><td>AutomatedDeviceCharacterization.vi&amp;nbsp;</td><td>LabView</td><td>Experimental Control Software by BYU</td><td>Found in the appendix</td></tr><tr><td>CompareWDMmodes.m</td><td>MATLab</td><td>Analytical Software by BYU</td><td>Found in the appendix</td></tr></tbody></table>

characterization of anisotropic leaky mode modulators for holovideo

Holovideo displays are based on light-bending spatial light modulators. One such spatial light modulator is the anisotropic leaky mode modulator. This modulator is particularly well suited for holographic video experimentation as it is relatively simple and inexpensive to fabricate1-3. Some additional advantages of leaky mode devices include: large aggregate bandwidth, polarization separation of signal light from noise, large angular deflection and frequency control of color1. In order to realize these advantages, it is necessary to be able to adequately characterize these devices as their operation is strongly dependent on waveguide and transducer parameters4. To characterize the modulators, the authors use a commercial prism coupler as well as a custom characterization apparatus to identify guided modes, calculate waveguide thickness and finally to map the device's frequency input and angular output of leaky mode modulators. This work gives a detailed description of the measurement and characterization of leaky mode modulators suitable for full-color holographic video.

Los resultados principales del protocolo anterior son la medición modo guiado del acoplador de prisma comercial muestra en la Figura 2, la frecuencia única, los datos de entrada sin procesar / salida recogidos del acoplador de prisma personalizado muestran en la Figura 8 y las curvas multicolores muestran en la Figura 9. en los siguientes párrafos se discute la información para la acción producida por cada una de estas salidas. ...

Watch this Scientific Journal Video about Characterization of Anisotropic Leaky Mode Modulators for Holovideo at JoVE.com

Characterization of Anisotropic Leaky Mode Modulators for Holovideo

Caracterización de anisotrópico de modo que gotean moduladores para holovídeo

This work describes fabrication and characterization of anisotropic leaky mode modulators for holographic video.

Holovideo displays are based on light-bending spatial light modulators.  One such spatial light modulator is the anisotropic leaky mode modulator.  This ...

characterization-of-anisotropic-leaky-mode-modulators-for-holovideo

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

7.9K vistas.  Brigham Young University. This work describes fabrication and characterization of anisotropic leaky mode modulators for holographic video.

Video: Characterization of Anisotropic Leaky Mode Modulators for Holovideo

Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The optical modes are frequently referred to as "whispering gallery modes" (WGM) or "morphology dependent resonances" (MDR) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology. The WGM-based sensor applications include those in biology7, trace gas detection8, and impurity detection in liquids9. Mechanical sensors based on microsphere resonators have also been proposed, including those for force10,11, pressure12, acceleration13 and wall shear stress14. In the present, we demonstrate a WGM-based electric field sensor, which builds on our previous studies15,16. A candidate application of this sensor is in the detection of neuronal action potential.
The electric field sensor is based on polymeric multi-layered dielectric microspheres. The external electric field induces surface and body forces on the spheres (electrostriction effect) leading to elastic deformation. This change in the morphology of the spheres, leads to shifts in the WGM. The electric field-induced WGM shifts are interrogated by exciting the optical modes of the spheres by laser light. Light from a distributed feedback (DFB) laser (nominal wavelength of ~ 1.3 &mu;m) is side-coupled into the microspheres using a tapered section of a single mode optical fiber. The base material of the spheres is polydimethylsiloxane (PDMS). Three microsphere geometries are used: (1) PDMS sphere with a 60:1 volumetric ratio of base-to-curing agent mixture, (2) multi layer sphere with 60:1 PDMS core, in order to increase the dielectric constant of the sphere, a middle layer of 60:1 PDMS that is mixed with varying amounts (2% to 10% by volume) of barium titanate and an outer layer of 60:1 PDMS and (3) solid silica sphere coated with a thin layer of uncured PDMS base. In each type of sensor, laser light from the tapered fiber is coupled into the outermost layer that provides high optical quality factor WGM (Q ~ 106). The microspheres are poled for several hours at electric fields of ~ 1 MV/m to increase their sensitivity to electric field.

A high-sensitivity photonic micro sensor was developed for electric field detection. The sensor exploits the optical modes of a dielectric sphere. Changes in the external electric field perturb the sphere morphology leading to shifts in its optical modes. The electric field strength is measured by monitoring these optical shifts.

Desarrollo de la Whispering Gallery Mode poliméricos micro-ópticos Sensores de campos eléctricos

Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The ...

Investigación

Ingeniería

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.

Almacenamiento cuasi-luz de los datos ópticos de paquetes

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

Compact Lens-less Digital Holographic Microscope for MEMS Inspection and Characterization

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and automotive. However, effective inspection and characterization metrology systems are needed to ensure the functional reliability of MEMS. This study presents a system based on digital holography as a tool for MEMS metrology. Digital holography has gained increasing attention in the past 20 years. With the fast development and decreasing cost of sensor arrays, resolution of such systems has increased broadening potential applications. Thus, it has attracted attention from both research and industry sides as a potential reliable tool for industrial metrology. Indeed, by recording the interference pattern between an object beam (which contains sample height information) and a reference beam on a CCD camera, one can retrieve the quantitative phase information of an object. However, most of digital holographic systems are bulky and thus not easy to implement on industry production lines. The novelty of the system presented is that it is lens-less and thus very compact. In this study, it is shown that the Compact Digital Holographic Microscope (CDHM) can be used to evaluate several characteristics typically consider as criteria in MEMS inspections. The surface profiles of MEMS in both static and dynamic conditions are presented. Comparison with AFM is investigated to validate the accuracy of the CDHM.

We present a compact reflection digital holographic system (CDHM) for inspection and characterization of MEMS devices. A lens-less design using a diverging input wave providing natural geometrical magnification is demonstrated. Both static and dynamic studies are presented.

Compacto holográfica microscopio digital Lente menos por MEMS Inspección y Caracterización

A micro-electro-mechanical-system (MEMS) is a widely used component in many industries, including energy, biotechnology, medical, communications, and ...

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.

Automatización de modo de bloqueo de rotación en un láser de fibra no lineal de polarización a través de mediciones de polarización de salida

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 ...

Design and Characterization Methodology for Efficient Wide Range Tunable MEMS Filters

Here, we demonstrate the advantages of the laser Doppler vibrometer (LDV) over conventional techniques (the network analyzer), as well as the techniques to create an application-based microelectromechanical systems (MEMS) filter and how to use it efficiently (i.e., tuning the tuning-capability and avoiding both failure and stiction). LDV enables crucial measurements that are impossible with the network analyzer, such as higher mode detection (highly sensitive biosensor application) and resonance measurement for very small devices (fast prototyping). Accordingly, LDV was used to characterize the frequency tuning range and resonance frequency at different modes of the MEMS filters built for this study. This wide range frequency tuning mechanism is based simply on Joule heating from the embedded heaters and relatively high thermal stress with respect to the temperature of a fixed-fixed beam. However, we demonstrate that another limitation of this method is the resulting high thermal stress, which can burn the devices. Further improvement was achieved and shown for the first time in this study, such that the tuning capability was increased by 32% through an increase in the applied DC bias voltage (25 V to 35 V) between the two adjacent beams. This important finding eliminates the need for the extra Joule heating at the wider frequency tuning range. Another possible failure is through stiction and requirement of structure optimization: We propose a simple and easy technique of low frequency square wave signal application that can successfully separate the beams and eliminates the need for the more sophisticated and complicated methods given in the literature. The above findings necessitate a design methodology, and so we also provide an application-based design.

A protocol for a fixed-fixed beam design using a laser Doppler vibrometer (LDV), including the measurement of frequency tuning, modification of tuning capability, and avoidance of device failure and stiction, is presented. The superiority of the LDV method over the network analyzer is demonstrated due to its higher mode capability.

Diseño y metodología de caracterización para filtros de MEMS Tunable eficiente toda la gama

Here, we demonstrate the advantages of the laser Doppler vibrometer (LDV) over conventional techniques (the network analyzer), as well as the techniques ...

An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The cholesteric LC is composed of a nematic LC 4&#39;-pentyloxy-4-cyanobiphenyl (5OCB), redox-responsive chiral dopant (FcD), and a supporting electrolyte 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIm-OTf). The most important component is FcD. This molecule changes its helical twisting power (HTP) value in response to redox reactions. Therefore, in situ electrochemical redox reactions in the LC mixture allow for the device to change its reflection color in response to electrical stimuli. The LC mixture was introduced, by a capillary action, into a sandwich-type ITO glass cell comprising two glass slides with patterned indium tin oxide (ITO) electrodes, one of which was coated with poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol) doped with perchlorate (PEDOT+). Upon application of +1.5 V, the reflection color of the device changed from blue (467 nm) to green (485 nm) in 0.4 s. Subsequent application of 0 V made the device recover the original blue color in 2.7 s. This device is characterized by its fastest electrical response and lowest operating voltage among any previously reported cholesteric LC device. This device could pave the way for the development of next generation reflective displays with low energy consumption rates.

A protocol for the fabrication of a reflective cholesteric liquid crystalline display device containing a redox-responsive chiral dopant allowing quick and low-voltage operation is presented.

Un dispositivo cristalino líquido colestérico electroquímico para modulación de Color rápida y de baja tensión

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The ...

Química

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.

Que forma la amplitud y fase de rayos láser mediante el uso de un modulador de luz espacial sólo fase

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

Fabrication and Characterization of Thickness Mode Piezoelectric Devices for Atomization and Acoustofluidics

We present a technique to fabricate simple thickness mode piezoelectric devices using lithium niobate (LN). Such devices have been shown to atomize liquid more efficiently, in terms of &#64258;ow rate per power input, than those that rely on Rayleigh waves and other modes of vibration in LN or lead zirconate titanate (PZT). The complete device is composed of a transducer, a transducer holder, and a &#64258;uid supply system. The fundamentals of acoustic liquid atomization are not well known, so techniques to characterize the devices and to study the phenomena are also described. Laser Doppler vibrometry (LDV) provides vibration information essential in comparing acoustic transducers and, in this case, indicates whether a device will perform well in thickness vibration. It can also be used to &#64257;nd the resonance frequency of the device, though this information is obtained more quickly via impedance analysis. Continuous &#64258;uid atomization, as an example application, requires careful &#64258;uid flow control, and we present such a method with high-speed imaging and droplet size distribution measurements via laser scattering.

Fabrication of piezoelectric thickness mode transducers via direct current sputtering of plate electrodes on lithium niobate is described. Additionally, reliable operation is achieved with a transducer holder and &#64258;uid supply system and characterization is demonstrated via impedance analysis, laser doppler vibrometry, high-speed imaging, and droplet size distribution using laser scattering.

Fabricación y caracterización de dispositivos piezoeléctricos en modo de espesor para atomización y acoustofluídicos

We present a technique to fabricate simple thickness mode piezoelectric devices using lithium niobate (LN). Such devices have been shown to atomize liquid ...

Demonstration of Spin-Multiplexed and Direction-Multiplexed All-Dielectric Visible Metaholograms

The optical holography technique realized by metasurfaces has emerged as a novel approach to projective volumetric display and information encryption display in the form of ultrathin and almost flat optical devices. Compared to the conventional holographic technique with spatial light modulators, the metahologram has numerous advantages such as miniaturization of optical setup, higher image resolution and larger field of visibility for holographic images. Here, a protocol is reported for the fabrication and optical characterization of optical metaholograms that are sensitive to the spin and direction of incident light. The metasurfaces are composed of hydrogenated amorphous silicon (a-Si:H), which has large refractive index and small extinction coefficient in the entire visible range resulting in high transmittance and diffraction efficiency. The device produces different holographic images when the spin or direction of incident light are switched. Therefore, they can encode multiple types of visual information simultaneously. The fabrication protocol consists of film deposition, electron beam writing and subsequent etching. The fabricated device can be characterized using a customized optical setup that consists of a laser, a linear polarizer, a quarter waveplate, a lens and a charge-coupled device (CCD).

We present a protocol for fabrication of spin- and direction-multiplexed visible metaholograms, then conduct an optical experiment to verify their function. These metaholograms can easily visualize encoded information, so they can be used for projective volumetric display and information encryption.

Demostración de metahologramas visibles girados multiplexados y multiplexados por dirección

The optical holography technique realized by metasurfaces has emerged as a novel approach to projective volumetric display and information encryption ...

Multi-step Variable Height Photolithography for Valved Multilayer Microfluidic Devices

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to entry for non-specialists who would benefit greatly from the ability to develop their own microfluidic devices to address research questions. Particularly lacking has been the open dissemination of protocols related to photolithography, a key step in the development of a replica mold for the manufacture of polydimethylsiloxane (PDMS) devices. While the fabrication of single height silicon masters has been explored extensively in literature, fabrication steps for more complicated photolithography features necessary for many interesting device functionalities (such as feature rounding to make valve structures, multi-height single-mold patterning, or high aspect ratio definition) are often not explicitly outlined. 
Here, we provide a complete protocol for making multilayer microfluidic devices with valves and complex multi-height geometries, tunable for any application. These fabrication procedures are presented in the context of a microfluidic hydrogel bead synthesizer and demonstrate the production of droplets containing polyethylene glycol (PEG diacrylate) and a photoinitiator that can be polymerized into solid beads. This protocol and accompanying discussion provide a foundation of design principles and fabrication methods that enables development of a wide variety of microfluidic devices. The details included here should allow non-specialists to design and fabricate novel devices, thereby bringing a host of recently developed technologies to their most exciting applications in biological laboratories.

Multilayer microfluidic devices often involve the fabrication of master molds with complex geometries for functionality. This article presents a complete protocol for multi-step photolithography with valves and variable height features tunable to any application. As a demonstration, we fabricate a microfluidic droplet generator capable of producing hydrogel beads.

Múltiples pasos Fotolitografia variable Altura de múltiples capas con válvula dispositivos de microfluidos

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to ...