Integrated optics technology study

The status and near term potential of materials and processes available for the fabrication of single mode integrated electro-optical components are discussed. Issues discussed are host material and orientation, waveguide formation, optical loss mechanisms, wavelength selection, polarization effects and control, laser to integrated optics coupling fiber optic waveguides to integrated optics coupling, sources, and detectors. Recommendations of the best materials, technology, and processes for fabrication of integrated optical components for communications and fiber gyro applications are given

Integrated optics technology study

The materials and processes available for the fabrication of single mode integrated electrooptical components are described. Issues included in the study are: (1) host material and orientation, (2) waveguide formation, (3) optical loss mechanisms, (4) wavelength selection, (5) polarization effects and control, (6) laser to integrated optics coupling,(7) fiber optic waveguides to integrated optics coupling, (8) souces, (9) detectors. The best materials, technology and processes for fabrication of integrated optical components for communications and fiber gyro applications are recommended

Optical and visual characterization of multifocal contact lenses and multifocal intraocular lenses

Vision is presented and universally accepted as the most precious of the human senses.lt is structured in three main parts: the optical system {eye), the photo-sensor {eye's retina), and the data processor (brain). If one of them is affected by any disease or dysfunction, vision will be terrible or even nonexistent One of the most common dysfunction is presbyopia.lt i s an age-related disorder that is undergone by all the population s ince their mid-late-40s and it is consists in the loss of the ability to focus near objects (accommodation). A huge number of possible corrections of it can be easily found. On one hand, there are temporary corrections ,as progressive spectacle tenses or multifocal contact tenses. On the other hand, permanent corrections as multifocal i ntraocular lenses, multifocal cornea! ablation, accommodating intraocular tenses, monovision systems, or scleral modifications are also applied to correct presbyopia. Another age-related dysfunction is cataract. Cataract is the opacification of the crystalline fens and decreases the quality of the visual function. Consequently, it is one of the leading visual impairments in adults over 60 years old, affecting the half of the adults aged between 75-85 years old. The only possible solution far cataract is the extraction of the opacified fibers of the crystalline lens and the replacement of them with an intraocular lens by surgery. Due to the fact that all the patients affected by an age-related cataract are also affected by presbyopia it is totally understandable that a number of patients choose mulltifocal introcular lens to substitute their crystalline tenses .This way, only one surgery is needed to salve both age-related dysfunctions. Usually, young presbyopes choose a temporary correction as a first option to correct presbyopia. Some presbyopia corrections are based on the simultaneous vision principie, as, far example, multifocal contact or intraocular lenses. The optical design of these kind of lenses is very complex. Consequently, It is characterization is also difficult When these lenses were launched into the market, it was only possible to characterize optical quality before the implantation or the adaptation of them (characterization in vitro) and the visual quality after the surgery or the clinical adaptation was performed (characterization) .M. present and thanks to the technological advances, different new commercial instruments that are to perform characterization in vivo of the visual quality before the implantation or the adaptation of simultaneous vis ion tenses. They are based on the simulation of the vision that these tenses give to the implanted eye. Some experimental prototypes and commercial aberrometers or double­ pass systems have used to perform an optical quality characterization in vivo, but some issues have been reported. Taking into account all this information, the main goal of this thesis is the design and the assembly of a new open-field double-pass system with asymmetric focus that is suitable to characterize invivo optical quality in patients implanted or adapted with multifocal intraocular or contact lenses. In order to achieve this aim, different studies and processes were carried out Review of presbyopia corrections and the characterization of them (Clinical study about objective over-refraction wearing multifocal contact lenses); Verification of the suitability of one commerciat simulator (Clinical study with the commercial simulator VirtlOL (10lens S.l.)); Design and assembly of the double-pass system with asymmetric focus (Opto-mechanical design/ Validation of all the elements included in the system/ Optical validation of the system); Programming of the softwares to manage the system; Validation of the new prototype (Two clinical studies characterizing eyes implanted with multifocal introcular tenses by using the new system were done).La visió és entesa i, universalment acceptada, com el sentit humà més valorat .Aquesta esta estructurada en tres parts principals: el sistema òptic (l'ull), el fot-sensor (la retina ocular) iel processador (el cervell). Si una d'aquestes parts es veu afectada per una disfunció o malaltia, la visió pot arribar a ser de molt baixa qualitat i, fins hi tot, inexistent Una de les disfuncions més comunes és la presbícia. La presbícia és una disfunció lligada a l'edat que pateix tota lla població a partir dels 40 anys, aproximadament. Consisteix en la pèrdua de la capacitat d'enfocar objectes propers (acomodació). Actualment, es troba un ampli nombre de possibles correccions. Per una banda, tenim les correccions temporals, com ulleres o lents de contacte progressives, i, per l'altre, correccions permanents, com lents intraoculars multifocals , ablacions corneals multifocals, lents intraoculars acomodatives, sistemes de monovisió, o modificacions esclerals, entre altres. Una altre disfunció associada a l'edat és la cataracta, la qual crea la opacificació del cristal·lí impedint una visió nítida. Conseqüentment, la cataracta és una de la deficiències visuals més estesa a partir dels 60 anys, afectant a la meitat de la població entre els 75 i els 85 anys . La única solució per eliminar les cataractes és eliminant les fibres opacificades i substituir-les per una lent intraocular quirúrgicament. Donat que tots els pacients amb cataractes són, a la vegada, prèsbites, està justificat que un nombre de pacients decideixi implantar-se lents intraoculars multifocals per substituir el seu cristal·lí. D'aquesta manera es solucionen dues degeneracions associades a l'edat en una sola cirurgia. Els joves prèsbites acostumen a optar per correccions prèsbites temporals, mentre que molts dels prèsbites amb cataractes opten per solucions permanents. Algunes de les correccions de la presbícia, com les lents de contacte o intraoculars multifocals , estan basades en el principi de visió simultània. Els dissenys òptics d'aquest tipus de lents són molt complexos, cosa que fa que la seva caracterització sigui molt complicada. Quan aquestes lents van aparèixer al mercat, només era possible caracteritzar-les òpticament abans de la seva implantació o adaptació de manera in vitro, i de caracteritzar-les visualment després de la seva adaptació o implantació de manera in vivo. Actualment, i gracies a tots els avenços tecnològics, diferents instruments clínics han estat desenvolupats per realitzar mesures de les qualitats visuals abans de la seva implantació. Tots ells, es basen en simular-li al pacient la visió que tindria després de ser implantat. Per un altre cantó, alguns prototips experimentals iaberrometres o sistemes de doble-pas comercials han estat utilitzats per dur a terme la caracterització de la qualitat in vim en pacients implantats o adaptats amb sistemes multifocals, pero diferents problemes han estat plantejats. Tenint en compte tota aquesta informació, el principal objectiu d'aquesta tesi ha estat la de dissenyar i muntar un nou sistema de doble-pas d'enfocament asimètric de camp obert que fos capaç de fer una caracterització de la qualitat òptica in vivo de pacients implantats o adaptats amb lents de contacte o intraoculars multifocals. I per arribar a aquest objectiu, s'han dut a terme els següents passos: Revisió de les correccions per a la presbícia i caracterització d'elles (Estudi clínic de la sobre-refracció objectiva de pacients adaptats amb lents de contacte multifocals); Validació de la capacitat de mesura d'un simulador comercial (Estudi clínic amb el simulador comercial VirtlOL (1OLens S.L); Disseny i muntatge del sistema de doble-pas amb enfocament asimètric (Disseny opto-mecànic/ Validació de tots els components del sistema/ Validació òptica del sistema); Programació dels programes informàtics que gestionen el sistema i processe

Optical and visual characterization of multifocal contact lenses and multifocal intraocular lenses

Vision is presented and universally accepted as the most precious of the human senses.lt is structured in three main parts: the optical system {eye), the photo-sensor {eye's retina), and the data processor (brain). If one of them is affected by any disease or dysfunction, vision will be terrible or even nonexistent One of the most common dysfunction is presbyopia.lt i s an age-related disorder that is undergone by all the population s ince their mid-late-40s and it is consists in the loss of the ability to focus near objects (accommodation). A huge number of possible corrections of it can be easily found. On one hand, there are temporary corrections ,as progressive spectacle tenses or multifocal contact tenses. On the other hand, permanent corrections as multifocal i ntraocular lenses, multifocal cornea! ablation, accommodating intraocular tenses, monovision systems, or scleral modifications are also applied to correct presbyopia. Another age-related dysfunction is cataract. Cataract is the opacification of the crystalline fens and decreases the quality of the visual function. Consequently, it is one of the leading visual impairments in adults over 60 years old, affecting the half of the adults aged between 75-85 years old. The only possible solution far cataract is the extraction of the opacified fibers of the crystalline lens and the replacement of them with an intraocular lens by surgery. Due to the fact that all the patients affected by an age-related cataract are also affected by presbyopia it is totally understandable that a number of patients choose mulltifocal introcular lens to substitute their crystalline tenses .This way, only one surgery is needed to salve both age-related dysfunctions. Usually, young presbyopes choose a temporary correction as a first option to correct presbyopia. Some presbyopia corrections are based on the simultaneous vision principie, as, far example, multifocal contact or intraocular lenses. The optical design of these kind of lenses is very complex. Consequently, It is characterization is also difficult When these lenses were launched into the market, it was only possible to characterize optical quality before the implantation or the adaptation of them (characterization in vitro) and the visual quality after the surgery or the clinical adaptation was performed (characterization) .M. present and thanks to the technological advances, different new commercial instruments that are to perform characterization in vivo of the visual quality before the implantation or the adaptation of simultaneous vis ion tenses. They are based on the simulation of the vision that these tenses give to the implanted eye. Some experimental prototypes and commercial aberrometers or double­ pass systems have used to perform an optical quality characterization in vivo, but some issues have been reported. Taking into account all this information, the main goal of this thesis is the design and the assembly of a new open-field double-pass system with asymmetric focus that is suitable to characterize invivo optical quality in patients implanted or adapted with multifocal intraocular or contact lenses. In order to achieve this aim, different studies and processes were carried out Review of presbyopia corrections and the characterization of them (Clinical study about objective over-refraction wearing multifocal contact lenses); Verification of the suitability of one commerciat simulator (Clinical study with the commercial simulator VirtlOL (10lens S.l.)); Design and assembly of the double-pass system with asymmetric focus (Opto-mechanical design/ Validation of all the elements included in the system/ Optical validation of the system); Programming of the softwares to manage the system; Validation of the new prototype (Two clinical studies characterizing eyes implanted with multifocal introcular tenses by using the new system were done).La visió és entesa i, universalment acceptada, com el sentit humà més valorat .Aquesta esta estructurada en tres parts principals: el sistema òptic (l'ull), el fot-sensor (la retina ocular) iel processador (el cervell). Si una d'aquestes parts es veu afectada per una disfunció o malaltia, la visió pot arribar a ser de molt baixa qualitat i, fins hi tot, inexistent Una de les disfuncions més comunes és la presbícia. La presbícia és una disfunció lligada a l'edat que pateix tota lla població a partir dels 40 anys, aproximadament. Consisteix en la pèrdua de la capacitat d'enfocar objectes propers (acomodació). Actualment, es troba un ampli nombre de possibles correccions. Per una banda, tenim les correccions temporals, com ulleres o lents de contacte progressives, i, per l'altre, correccions permanents, com lents intraoculars multifocals , ablacions corneals multifocals, lents intraoculars acomodatives, sistemes de monovisió, o modificacions esclerals, entre altres. Una altre disfunció associada a l'edat és la cataracta, la qual crea la opacificació del cristal·lí impedint una visió nítida. Conseqüentment, la cataracta és una de la deficiències visuals més estesa a partir dels 60 anys, afectant a la meitat de la població entre els 75 i els 85 anys . La única solució per eliminar les cataractes és eliminant les fibres opacificades i substituir-les per una lent intraocular quirúrgicament. Donat que tots els pacients amb cataractes són, a la vegada, prèsbites, està justificat que un nombre de pacients decideixi implantar-se lents intraoculars multifocals per substituir el seu cristal·lí. D'aquesta manera es solucionen dues degeneracions associades a l'edat en una sola cirurgia. Els joves prèsbites acostumen a optar per correccions prèsbites temporals, mentre que molts dels prèsbites amb cataractes opten per solucions permanents. Algunes de les correccions de la presbícia, com les lents de contacte o intraoculars multifocals , estan basades en el principi de visió simultània. Els dissenys òptics d'aquest tipus de lents són molt complexos, cosa que fa que la seva caracterització sigui molt complicada. Quan aquestes lents van aparèixer al mercat, només era possible caracteritzar-les òpticament abans de la seva implantació o adaptació de manera in vitro, i de caracteritzar-les visualment després de la seva adaptació o implantació de manera in vivo. Actualment, i gracies a tots els avenços tecnològics, diferents instruments clínics han estat desenvolupats per realitzar mesures de les qualitats visuals abans de la seva implantació. Tots ells, es basen en simular-li al pacient la visió que tindria després de ser implantat. Per un altre cantó, alguns prototips experimentals iaberrometres o sistemes de doble-pas comercials han estat utilitzats per dur a terme la caracterització de la qualitat in vim en pacients implantats o adaptats amb sistemes multifocals, pero diferents problemes han estat plantejats. Tenint en compte tota aquesta informació, el principal objectiu d'aquesta tesi ha estat la de dissenyar i muntar un nou sistema de doble-pas d'enfocament asimètric de camp obert que fos capaç de fer una caracterització de la qualitat òptica in vivo de pacients implantats o adaptats amb lents de contacte o intraoculars multifocals. I per arribar a aquest objectiu, s'han dut a terme els següents passos: Revisió de les correccions per a la presbícia i caracterització d'elles (Estudi clínic de la sobre-refracció objectiva de pacients adaptats amb lents de contacte multifocals); Validació de la capacitat de mesura d'un simulador comercial (Estudi clínic amb el simulador comercial VirtlOL (1OLens S.L); Disseny i muntatge del sistema de doble-pas amb enfocament asimètric (Disseny opto-mecànic/ Validació de tots els components del sistema/ Validació òptica del sistema); Programació dels programes informàtics que gestionen el sistema i processenPostprint (published version

Silicon-Organic Hybrid Platform for Photonic Integrated Circuits

Die vorliegende Arbeit erkundet das technische Potential einer neuen Plattform für hochintegrierte Optik. Diese Plattform kombiniert ausgewählte organische Materialien mit optischen, integrierten Schaltungen der Silizium-Photonik zu silizium-organischen Hybrid-Bauteilen (SOH) mit außergewöhnlichen Eigenschaften, d.h. Eigenschaften, welche Silizium allein nicht besitzt. Es werden Schlüsselkomponenten wie Laser und Modulatoren konzipiert und mit CMOS-basierten Technologien hergestellt

High-speed low-power modulator driver arrays for medium-reach optical networks

The internet is becoming the ubiquitous tool that is changing the lives of so many citizens across the world. Commerce, government, industry, healthcare and social interactions are all increasingly using internet applications to improve and facilitate communications. This is especially true for videoenabled applications, which currently demand much higher data rates and quality from data networks. High definition TV streaming services are emerging and these again will significantly push the demand for widely deployed, high-bandwidth services. The current access passive optical networks (PONs) use a single wavelength for downstream transmission and a separate one for upstream transmission. Incorporating wavelength-division multiplexing (WDM) in a PON allows for much higher bandwidths in both directions. While WDM technologies have been successfully deployed for many years in metro and core networks, in access networks they are not commonly used yet. This is mainly due to the high costs associated with deploying entire WDM access networks. However, the present optical networks cannot be simply and cost-effectively scaled to provide the capacity for tomorrow’s users. As an effect there is a strong need for new WDM access components which are compact, cost-competitive and mass-manufacturable. Increasing the number of wavelengths for WDM-PON automatically leads to an increase in the number of single pluggable transceivers, which brings substantial design challenges and additional costs. The multitude of TXs and RXs for different wavelength channels increases the total footprint considerably. Photonic integration of transceivers into arrays will significantly reduce the footprint and cost. However, the total power consumption of an array device is an issue. To avoid the use of a thermoelectric cooler, the integration density of components is severely limited by the heat dissipating capabilities offered by their package. As a result the WDM-PON philosophy necessitates the reduction of the transceiver’s power dissipation. From this plea it is apparent that the main technology challenges for realizing future-proof optical (access) networks are reducing active component power consumption, shrinking form factors and lowering assembly costs. In this perspective an over 100 Gb/s throughput component, composed of 10 channels at 11.3 Gb/s per wavelength channel would be a great contribution to the expansion of customer bandwidth. It can provide increased line rates to the end users at speeds of 10 Gb/s per wavelength. As RXs typically consume much less power than externally modulated TXs, they can relatively easily be integrated into an array. Mainly high speed optical transmitters have significant power consumptions and the heat generation caused by power dissipation forms a critical obstacle in the development of a 10-channel transmitter, which again underlines the importance of power reduction. Alongside the introduction of WDM in access networks, also inter-office point-to-point connections in data center environments could benefit from the WDM philosophy. As data center operators often suffer from fiber scarcity or do not own their fiber infrastructure, WDM technologies are essential to deliver reach and capacity extension for these scenarios. Interdata center communication also benefits from cost-, footprint- and energyefficient components operating at high speed to maximize the throughput. As an effect integrated over 100 Gb/s transceivers, such as 4 channels at 28 Gb/s, are highly desirable. The research described in this dissertation was partly funded by the European FP7 ICT project C3PO (Colourless and Coolerless Components for low Power Optical Networks) and the UGent special research fund. The C3PO project aimed to develop a new generation of green Si-photonic compatible components with record low power consumption, that can enable bandwidth growth and constrain the total cost. C3PO envisioned building high-capacity access networks employing reflective photonic components. To achieve this, cost-competitive reflective transmitters based on electroabsorption modulators (EAM) needed to be closely integrated into arrays. A multi-wavelength optical source provides the required wavelength channels for both downstream and upstream signals in the WDM-PON. Chapter 1 gives a short overview of a PON and describes the main implementations of a WDM-PON access network. It introduces integrated low power transmitter arrays for a cost-effective architecture of WDM-PONs and inter-data center communication. Chapter 2 compares different optical transmitters and gives a short overview of their most important characteristics. External modulation through both Mach-Zehnder modulators (MZMs) and EAMs is described. It shows that EAMs are the best choice for low power transmitter array integration, thanks to their lower drive voltage and smaller form factor, compared to MZMs. To achieve a reduced consumption, the electronic modulator driver topology is studied in chapter 3. The challenge in designing modulator drivers is the need to deliver very large currents in combination with high voltage swings. Four distinct output configurations are compared and techniques to reduce the power consumption of the drivers are described. Chapter 5 presents duobinary (DB), a modulation scheme that is gaining interest in today’s optical transmission. As the required bandwidth is about half that of NRZ, it softens the constraints on the transmitter bandwidth. Thanks to its narrow optical spectrum, it has an improved tolerance to dispersion in long haul single mode links and it can improve the spectral efficiency in WDM architectures. For optical DB a precoder is necessary to assure the received signal is equal to the original binary signal. The conducted research that resulted in this dissertation produced 2 low power EAM driver arrays: A 10-channel 113 Gb/s modulator driver array with state-of-the art ultra-low power consumption. A 2-channel 56 Gb/s duobinary driver array with a differential output with low power consumption. Both designs are elaborately analyzed in chapter 4 and 6 respectively. To the best of our knowledge the 10-channel EAM driver array is the first in its kind, while achieving the lowest power consumption for an EAM driver so far reported, 50% below the state of the art in power consumption. The 2-channel EAM driver array is the fastest modulator driver including on-chip duobinary encoding and precoding reported so far. The final chapter provides an overview of the foremost conclusions from the presented research. It is concluded with suggestions for further research

LASER Tech Briefs, Spring 1994

Topics in this Laser Tech Brief include: Electronic Components and Circuits. Electronic Systems, Physical Sciences, Materials, Mechanics, Fabrication Technology, and books and reports

Photodetectors

In this book some recent advances in development of photodetectors and photodetection systems for specific applications are included. In the first section of the book nine different types of photodetectors and their characteristics are presented. Next, some theoretical aspects and simulations are discussed. The last eight chapters are devoted to the development of photodetection systems for imaging, particle size analysis, transfers of time, measurement of vibrations, magnetic field, polarization of light, and particle energy. The book is addressed to students, engineers, and researchers working in the field of photonics and advanced technologies

Optoelectronic devices based on van der Waals heterostructures

In this thesis we investigate the use of van der Waals heterostructures in optoelec- tronic devices. An improvement in the optical and electronic performance of specific devices can be made by combining two or more atomically thin materials in layered structures. We demonstrate a heterostructure photodetector formed by combining graphene with tungsten disulphide. These photodetectors were found to be highly sensitive to light due to a gain mechanism that produced over a million electrons per photon. This arises from the favourable electrical properties of graphene and the strong light-matter interaction in WS2 . An analysis of the photodetector per- formance shows that these devices are capable of detecting light under moonlight illuminations levels at video-frame-rate speeds with applications in night vision ima- ging envisaged. We also report a novel method for the direct laser writing of a high-k dielectric embedded inside a van der Waals heterostructure. Such structures were shown to be capable of both light-detection and light-emission within the same de- vice architecture, paving the way for future multifunctional optoelectronic devices. Finally we address a more fundamental problem in the properties of aligned grap- hene/hBN heterostructures. Strain distributions are shown to modify the electronic properties of graphene due to a change in the interlayer interaction. We demon- strates a method to engineer these strain patterns by contact geometry design and thermal annealing strategies.Engineering and Physical Sciences Research Council (EPSRC