Data compressive paradigm for spectral sensing and classification using electrically tunable detectors

This dissertation contains three major parts: (1) demonstration of the algorithmic spectrometry in the mid-IR sensing regime using spectrally tunable quantum dots-in-a-well (DWELL) IR detector without employing any spectral filters; (2) further demonstration of the spectral-classification capability of tunable DWELL IR focal-plane array (FPA), again without using any spectral filters; and (3) development of a generalized filter-free data-compressive spectral sensing paradigm using the DWELL detector that enables arbitrarily specified MS sensing (e.g., spectral matched filtering, slope sensing, multicolor sensing, etc.) without using any spectral filters and possibly under constrained acquisition times

Spectral LADAR: Active Range-Resolved Imaging Spectroscopy

Imaging spectroscopy using ambient or thermally generated optical sources is a well developed technique for capturing two dimensional images with high per-pixel spectral resolution. The per-pixel spectral data is often a sufficient sampling of a material's backscatter spectrum to infer chemical properties of the constituent material to aid in substance identification. Separately, conventional LADAR sensors use quasi-monochromatic laser radiation to create three dimensional images of objects at high angular resolution, compared to RADAR. Advances in dispersion engineered photonic crystal fibers in recent years have made high spectral radiance optical supercontinuum sources practical, enabling this study of Spectral LADAR, a continuous polychromatic spectrum augmentation of conventional LADAR. This imaging concept, which combines multi-spectral and 3D sensing at a physical level, is demonstrated with 25 independent and parallel LADAR channels and generates point cloud images with three spatial dimensions and one spectral dimension. The independence of spectral bands is a key characteristic of Spectral LADAR. Each spectral band maintains a separate time waveform record, from which target parameters are estimated. Accordingly, the spectrum computed for each backscatter reflection is independently and unambiguously range unmixed from multiple target reflections that may arise from transmission of a single panchromatic pulse. This dissertation presents the theoretical background of Spectral LADAR, a shortwave infrared laboratory demonstrator system constructed as a proof-of-concept prototype, and the experimental results obtained by the prototype when imaging scenes at stand off ranges of 45 meters. The resultant point cloud voxels are spectrally classified into a number of material categories which enhances object and feature recognition. Experimental results demonstrate the physical level combination of active backscatter spectroscopy and range resolved sensing to produce images with a level of complexity, detail, and accuracy that is not obtainable with data-level registration and fusion of conventional imaging spectroscopy and LADAR. The capabilities of Spectral LADAR are expected to be useful in a range of applications, such as biomedical imaging and agriculture, but particularly when applied as a sensor in unmanned ground vehicle navigation. Applications to autonomous mobile robotics are the principal motivators of this study, and are specifically addressed

LASER Tech Briefs, September 1993

This edition of LASER Tech briefs contains a feature on photonics. The other topics include: Electronic Components and Circuits. Electronic Systems, Physical Sciences, Materials, Computer Programs, Mechanics, Machinery, Fabrication Technology, Mathematics and Information Sciences, Life Sciences and books and reports

Advanced arrayed waveguide gratings: models, design strategies and experimental demonstration

[EN] The present PhD thesis deals on the model, design and experimental demonstration of Arrayed Waveguide Grating (AWG) with advanced features. Firstly, building upon existing AWG formulations, design equations are provided, libraries developed and all this is experimentally validated with devices in Indium Phosphide (InP) and Silicon-on-insulator (SOI) technologies. Next, a model and experimental validation is reported for an Interleave-Chirped Arrayed Waveguide Grating (IC-AWG), which is able to process optical signals as WDM demultiplexer, polarization splitter and phase diversity component all in a single device. This device was fabricated and tested in InP technology. The second innovative AWG demonstrated in this thesis, a Reflective type (R-AWG), whose layout allows for tailoring the pass-band shape and to change the spectral resolution. A demonstration of design and fabrication for this device is provided in SOI technology. The last AWG with innovative concepts is one driven by Surface Acoustic Waves (AWG-SAW), where the spectral channels can be tuned by means of acousto-optic effect. The device was fabricated in Aluminium Gallium Arsenide (AlGaAs) technology, and measurements are provided to validate the concept and design flow. In parallel this thesis has resulted in the development of different AWG layouts for a wide number of (generic) technologies and foundries, coded into design libraries, of use in a de-facto standard software employed for the design of photonic integrated circuits. These design libraries have been licensed to the UPV spin-off company VLC Photonics S.L.[ES] La presente tesis se ha centrado en el modelado, diseño y demostración experimental del dispositivo Arrayed Waveguide Grating (AWG) con funcionalidades avanzadas. Primero, usando la formulación existente sobre AWGs se aportan ecuaciones y librerías de diseño, y se validan experimentalmente por medio de dispositivos fabricados en tecnologías de Indium Phosphide (InP) y Silicon-on-insulator (SOI). Después, se reporta un modelo y demostración experimental para un Interleave-Chirped Arrayed Waveguide Grating (IC-AWG), el cual es capaz de procesar señales ópticas como demultiplexor WDM, divisor de polarización y componente de diversidad de fase en un único dispositivo. Este dispositivo fue fabricado y probado en tecnología de InP. El segundo AWG innovador demostrado en esta tesis es de tipo Reflectante (R-AWG), cuyo diseño permite modificar la forma espectral del canal y cambiar su resolución espectral, incluyendo una demostración de diseño y fabricación de este dispositivo en tecnología de SOI. El último AWG que incluye conceptos innovadores es uno sintonizable por Acoustic Waves (AWGSAW), donde los canales espectrales pueden ser sintonizados por medio del efecto acusto-óptico. Dicho dispositivo fue fabricado en tecnología de Aluminium Gallium Arsenide (AlGaAs), y se han incluido medidas experimentales para validar el concepto y el flujo de diseño. En paralelo junto con esta tesis se han desarrollado diferentes diseños para el AWG en un amplio número de tecnologías (genéricas) y plataformas de fabricación, implementadas en unas librerías de diseño para uno de los softwares m¿as utilizados para el diseño de circuitos integrados ópticos, siendo actualmente el estándar de facto. Dichas librerías de diseño han sido licenciadas a la compañía VLC Photonics S.L., spin-off de la UPV.[CA] La present tesi ha estat centrada en el modelatge, disseny i demostració experimental del dispositiu Arrayed Waveguide Grating (AWG) amb funcionalitats avançades. Primer, usant la formulació existent sobre AWGs s'aporten equacions i llibreries de disseny, i es validen experimentalment per mitjà de dispositius fabricats en tecnologies de Indium Phosphide (InP) i Silicon-on-insulator (SOI). Després, es reporta un model i demostració experimental per a un Interleave-Chirped Arrayed Waveguide Grating (IC-AWG), el qual és capaç de processar senyals òptiques com demultiplexor WDM, divisor de polarització i component de diversitat de fase en un únic dispositiu. Aquest dispositiu va ser fabricat i provat en tecnologia de InP. El segon AWG innovador demostrat en aquesta tesi és de tipus Reflector (R-AWG), amb un disseny que permet modificar la forma espectral del canal i canviar la seua resolució espectral, incloent una demostració de disseny i fabricació d'aquest dispositiu en tecnologia de SOI. L'últim AWG que inclou conceptes innovadors és un sintonitzable per Acoustic Waves (AWG-SAW), on els canals espectrals poden ser sintonitzats per mitjà de l'efecte acusto-òptic. Aquest dispositiu va ser fabricat en tecnologia de Aluminium Gallium Arsenide (AlGaAs), i s'han inclòs mesures experimentals per validar el concepte i el flux de disseny. En paral.lel juntament amb aquesta tesi s'han desenvolupat diferents dissenys per al AWG en un ampli nombre de tecnologies (genèriques) i plataformes de fabricació, implementades en unes llibreries de disseny per a un dels programaris més utilitzats per al disseny de circuits integrats òptics, sent actualment l'estàndard de facto. Aquestes llibreries de disseny han estat llicenciades a la companyia VLC Photonics S.L., spin-off de la UPV.Gargallo Jaquotot, BA. (2016). Advanced arrayed waveguide gratings: models, design strategies and experimental demonstration [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/74646TESI

Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries

This report summarizes technical progress during the program “Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries”, performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The objective of this program was to use technology recently invented at Virginia Tech to develop and demonstrate the application of self-calibrating optical fiber temperature and pressure sensors to several key energy-intensive industries where conventional, commercially available sensors exhibit greatly abbreviated lifetimes due primarily to environmental degradation. A number of significant technologies were developed under this program, including • a laser bonded silica high temperature fiber sensor with a high temperature capability up to 700°C and a frequency response up to 150 kHz, • the world’s smallest fiber Fabry-Perot high temperature pressure sensor (125 x 20 μm) with 700°C capability, • UV-induced intrinsic Fabry-Perot interferometric sensors for distributed measurement, • a single crystal sapphire fiber-based sensor with a temperature capability up to 1600°C. These technologies have been well demonstrated and laboratory tested. Our work plan included conducting major field tests of these technologies at EPRI, Corning, Pratt & Whitney, and Global Energy; field validation of the technology is critical to ensuring its usefulness to U.S. industries. Unfortunately, due to budget cuts, DOE was unable to follow through with its funding commitment to support Energy Efficiency Science Initiative projects and this final phase was eliminated

NASA SBIR abstracts of 1992, phase 1 projects

The objectives of 346 projects placed under contract by the Small Business Innovation Research (SBIR) program of the National Aeronautics and Space Administration (NASA) are described. These projects were selected competitively from among proposals submitted to NASA in response to the 1992 SBIR Program Solicitation. The basic document consists of edited, non-proprietary abstracts of the winning proposals submitted by small businesses. The abstracts are presented under the 15 technical topics within which Phase 1 proposals were solicited. Each project was assigned a sequential identifying number from 001 to 346, in order of its appearance in the body of the report. Appendixes to provide additional information about the SBIR program and permit cross-reference of the 1992 Phase 1 projects by company name, location by state, principal investigator, NASA Field Center responsible for management of each project, and NASA contract number are included

Fiber optic sensors and self-reference techniques for temperature measurements in different industrial sectors

Mención Internacional en el título de doctorEl objetivo de este trabajo se centra especialmente en el desarrollo de sensores de fibra óptica y técnicas de autoreferencia para la medida de la temperatura en diferentes entornos industriales. El primer objetivo de este trabajo consiste en el diseño y desarrollo de un sensor de fibra óptica de bajo coste para la medida de la temperatura en transformadores de potencia y aplicaciones biomédicas. En estas aplicaciones, el uso de sensores de temperatura tradicionales resulta inadecuado debido a la presencia de fuertes interferencias electromagnéticas que pueden perturbar la lectura de la temperatura. Uno de los requisitos fundamentales para diseñar un sensor de temperatura que pueda usarse en aplicaciones biomédicas es el uso de materiales biocompatibles en su fabricación. En este sentido, una configuración simple que permite cumplir con los requisitos mencionados anteriormente es la modulación por intensidad en fibras poliméricas. Este tipo de sensores basan la lectura de la temperatura en medir las variaciones de potencia óptica en función de los cambios de temperatura que se aplican sobre el sensor. En este contexto, el uso de la tecnología asociada con la fibra óptica de plástico ofrece ventajas competitivas frente a otros materiales, como son: el uso de dispositivos opto-electrónicos de bajo coste, la posibilidad de utilizar conectores de baja precisión, la posibilidad de utilizar multiplexores y demultiplexores de muy bajo coste, entre muchas otras ventajas. A pesar de estas ventajas, los sensores de intensidad necesitan de esquemas de autoreferencia que eviten fluctuaciones de potencia que interfieran en la lectura de la temperatura. Estas fluctuaciones pueden provenir de fluctuaciones de potencia a lo largo del tramo de fibra óptica entre la unidad de control y el sensor, fluctuaciones de la fuente de luz por cambios en la corriente de alimentación, pérdidas de potencia por envejecimiento de la instalación, entre otras causas. El segundo objetivo de este trabajo consiste en promover el estudio y el desarrollo de técnicas de multiplexado y autoreferencia que implementen sensores fabricados en fibra óptica de plástico. Estas topologías deberán de utilizar dispositivos eficientes desde el punto de vista del consumo de potencia para mejorar con ello el balance de potencias del sistema y por tanto, poder utilizar este tipo de esquemas en redes de corto y medio alcance. Para alcanzar este objetivo, en este trabajo se desarrollan técnicas de autoreferencia y multiplexado de bajo coste basadas en multiplexación por longitud de onda vasta (CWDM, Coarse Wavelength Division Multiplexing). Esta técnica se caracteriza por su amplio desarrollo en el campo de telecomunicaciones como estándar para aplicaciones de corto o medio alcance en redes metropolitanas. Los multiplexores y demultiplexores diseñados para esta topología tienen una rejilla de longitudes de onda con una separación entre canales de 20nm. Este espaciado entre canales dificulta la multiplexación de un elevado número de dispositivos o sensores como podría llevarse a cabo si se usaran dispositivos basados en multiplexación por longitud de onda densa (DWDM, Dense Wavelength Division Multiplexing). Pero presentan una clara ventaja competitiva, los esquemas CWDM requieren bajas tolerancias en la fabricación de fuentes de luz, un control menos exhaustivo de la temperatura de la fuente, filtros ópticos de bajo coste y esquemas de diseño menos complejos. Los menores requisitos técnicos de los dispositivos utilizados con esta tecnología hacen que sea una topología interesante para su uso en redes de sensores de bajo coste. El tercer objetivo consiste en desarrollar sensores sin contacto basados en pirometría de dos colores para el sensado de la temperatura en procesos de mecanizado industrial...As a general aim, this work specifically focuses on the development of temperature sensors and self-reference techniques for temperature measurement in different industrial sectors. The first objective of this work is the design and development of a low-cost fiber optic sensor for measuring temperature in power transformers and biomedical applications where the presence of EMI prohibits the use of traditional sensors. Compatibility with the human being is a requirement when the temperature sensors are used in medical applications. Following simple fiber optic configurations, intensity sensors modulate the optical power loss as the temperature changes, thus providing the measurement as an optical intensity modulation signal. Polymer Optical Fiber (POF) technology, with very low-cost components, enables temperature sensing using a low precision connectors and lenses as well as simple multiplexing and demultiplexing devices, especially if compared with glass optical fibers. However, intensity sensors need a self-referencing method to minimize the influences of long-term aging of source and receptor characteristics, as well as undesirable random short-term fluctuations of optical power loss in the fiber link connecting the control unit, where the measurements are taken, to the remote sensing point, where the optical sensor is located. The second objective of this work is to promote, study and develop a multiplexing strategy to implement and scale POF sensor networks using low cost off-the-shelf devices, enhancing the power budget and keeping the self-reference of the measurements. This work focuses on low-cost Coarse WDM (CWDM) technology, where a grid of wavelengths with a 20nm channel spacing for target distance of up to tens of kilometres is specified. CWDM technology have lately been promoted in the field of telecommunication as standard for metro applications with shorter distances, lower network capacity and cost than Dense WDM (DWDM). This topology requires simpler, wider tolerance laser manufacturing, less laser accurate temperature control and reduced design complexity and cost of optical filters. These relaxed requirements make the CWDM technology an interesting approach for building low-cost self-referencing sensors networks. The development of this technology, adapted to the use of POF, can be carried out with the development of fiber Bragg gratings (FBG) in POF, providing an effective and compact strategy for exploiting fiber links for both propagating directions of the light with a single fiber lead. The third objective is to develop a non-contact two-colour fiber-optic pyrometer for temperature measures in the aerospace machining industry, enhancing the location measurement area, reducing the surface emissivity effect and keeping the self-reference of the measurement…The research work of this dissertation has been supported by the following Spanish projects: TEC2009-14718-C03-03 (DEDOS), and TEC2012-37983-C03-02 (CFOOT-TIC) of the Spanish Interministerial Commission of Science and Technology (CICYT); BES-2010-033348, EEBB-I-12-05434 and EEBB-1-13-07511 of the Spanish Ministry of Economy and Competitiveness; PRX12/00007 of Spanish Ministry of Education; P2013/MIT-2790, FACTOTEM-2/2010/00068/001 and S2013/MIT-2790 (SINFOTON-CM) of Autonomous Community of Madrid. Additional financial support was obtained from ICT COST Action TD1001: Novel and Reliable Optical Fiber Sensor Systems for Future Security and Safety Applications (OFSESA) of the European Union.Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y AutomáticaPresidente: Tianxin Yang.- Secretario: Ricardo Vergaz Benito.- Vocal: Kevin Heggart

NASA Tech Briefs, December 1999

Topics include: Imaging/Videos/Cameras; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Books and Reports

Entangled Photon Interferometry: Development of Photonic Systems Towards Quantum Spectroscopy

Entangled photon spectroscopy is an emergent field offering the potential to perform nonlinear and non-classical measurements at low photon fluxes. The entangled photon pairs which are generated using a continuous-wave laser pumped spontaneous parametric downconversion (SPDC) process simultaneously display strong correlations in time and anti-correlations in frequency space. Measuring changes in these correlations provides classical and non-classical information about the underlying dynamics and fluctuations of the sample-system. Further, because these two variables are not Fourier conjugates, entangled photon spectroscopy makes it possible to exploit the spectral resolution of continuous-wave lasers, while leveraging the temporal relationship of the near-simultaneously generated photon pairs which effectively mimics an ultrafast pulsed laser experiment. Nonlinear and ultrafast measurements can therefore be performed with low-power sources while also achieving superior signal-to-noise ratios due to the underlying quantum statistics. As photons in a pair can be separately manipulated, spectroscopic setups using these quantum states of light have marked benefits in contrast to measurements performed using traditional single photon states. Here, we describe our efforts towards implementing quantum interferometers to test the abilities of entangled photon pairs in nonlinear spectroscopic studies. Specifically, we present work on the development of free-space, fiber-optic, and nanophotonic systems that leverage nonlinear materials to generate narrow to broadband entangled photon pairs via SPDC. The numerical methods used for designing and tailoring these entangled photon sources are outlined together with associated experimental limitations. The spectral-temporal correlations of the two-photon states are characterized using fourth-order interferometry, demonstrating Hong-Ou-Mandel interference with picoseconds to femtoseconds coherence times, and wavelengths ranging from the IR to the UV. A monolithic nanophotonics architecture is proposed for completely on-chip, entangled, ultrafast, and nonlinear spectroscopy.</p