Efficient Optical Couplings for Fiber-Distributed Solar Lighting

Solar Energy ◽  
2003 ◽  
Author(s):  
L. C. Maxey ◽  
M. R. Cates ◽  
S. L. Jaiswal
Keyword(s):  
Optical Fibers ◽  
Optical Waveguides ◽  
Large Core ◽  
Index Matching ◽  
Refractive Index Matching ◽  
Solar Lighting ◽  
The Individual ◽  
Insertion Losses ◽  
The Impact ◽  
Loss Mechanisms

Optical couplings in large core optical waveguides have many similarities with those in conventional optical fibers but pose some unconventional challenges as well. The larger geometry, looser manufacturing tolerances and reduced dimensional stability compound the problems associated with making low-loss couplings in large core waveguides. The individual factors contributing to coupling losses are discussed to develop an understanding of the extant loss mechanisms. Individual methods and materials employed to mitigate the impact of each of the dominant loss mechanisms are discussed in detail. A combination of endface geometry control, axial alignment constraint and refractive index matching are employed to produce highly efficient optical couplings in large core waveguides. The combination of these elements has significantly reduced the insertion losses due to connector couplings. Prior to implementing the current methods losses of 15% and greater were common but these have been reduced to 2%–5% with the current methods.

scholarly journals Fabrication of Polyimide Optical Waveguide on Silicon Dioxide Layer Stacked Silicon Substrate

2017 ◽  
Vol 17 (2) ◽  
pp. 36
Author(s):  
Dadin Mahmudin ◽  
Shobih ◽  
Pamungkas Daud ◽  
Yusuf Nur Wijayanto
Keyword(s):  
Silicon Dioxide ◽  
Optical Fibers ◽  
Silicon Substrate ◽  
Optical Waveguides ◽  
Ultra Violet ◽  
Long Distance ◽  
Distance Communication ◽  
Paper Fabrication ◽  
Insertion Losses ◽  
Planar Optical Waveguides

Optical waveguides are important for guiding lightwave from a place to other places. Propagation and insertion losses of the optical waveguides should be considered to be in low values. Recently, optical waveguides with circular structures, which are optical fibers, are used widely for guiding lightwave in long-distance optical communication with very low propagation and insertion losses. Simultaneously, optical waveguides with planar structure are also developed for short distance communication in optical devices. We have reported design and analysis of the planar optical waveguides. In this paper, fabrication of planar optical waveguides using a polyimide material on thin silicon dioxide combined with the silicon substrate is reported. The polyimide material is used for the core of the optical waveguides. The silicon dioxide located on the silicon substrate and the air is used for cladding of the optical waveguides. Fabrication of the optical waveguides such as oxidation, photoresist coating, masking, ultra-violet exposure, and etching was done. The fabricated optical waveguides were characterized physically using a standard microscope and scanning electron microscope (SEM). The fabrication processes and characterization results are reported and discussed in detail.

Fact and Artefact in Confocal Microscopy

1997 ◽  
Vol 11 (4) ◽  
pp. 433-441 ◽  
Author(s):  
T.F. Watson
Keyword(s):  
Fluorescent Dyes ◽  
Numerical Aperture ◽  
Two Photon ◽  
Maximum Resolution ◽  
Index Matching ◽  
Refractive Index Matching ◽  
A Cell ◽  
Investigative Technique ◽  
The Individual ◽  
Combining Information

High-resolution confocal microscopic images may be made of either the surface of a sample or beneath the surface. These images can be likened to optical tomograms, giving thin (> 0.35 μm) slices up to 200 μm below the surface of a transparent tissue: With microscopes running under normal conditions, the optical section thickness will be >1 μm and the effective penetration into enamel and dentin a maximum of 100 μm. For maximum resolution, high-quality, high-numerical-aperture objectives should be used. Refractive index matching of the lens immersion media and the substrate will avoid distortions of images in the optical axis. Such errors could occur when imaging a considerable distance (> 40 μm) into a cell containing water, with an oil immersion objective above the cover slip. Care should be taken in the interpretation of computerized z axis reconstructions made from serial optical sections: Their validity should be checked with equivalent views made with the sample oriented in the same direction as the reconstruction. The use of fluorescent dyes in microscopy is a very powerful investigative technique. It is important that the dyes used not be labile and that they be well-fixed to the materials being examined, or the images may indicate the dye distribution rather than the material to which it is "attached". Multiple labeling experiments must have crossover control experiments to verify the distribution of the individual dyes. Valuable information can often be gained by combining information from both reflection and fluorescence images. Two-photon laser excitation of dyes gives the potential for greater depth penetration and improved resolution.

THICK PHOTORESIST ORIGINAL MASTER: A NEW TOOL FOR FABRICATION OF POLYMERIC OPTICAL WAVEGUIDES WITH LARGE CORE BY HOT EMBOSSING

2004 ◽  
Vol 13 (03n04) ◽  
pp. 513-517 ◽  
Author(s):  
HIROTAKA MIZUNO ◽  
OKIHIRO SUGIHARA ◽  
TOSHIKUNI KAINO ◽  
YUKA OHE ◽  
NAOMICHI OKAMOTO ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Optical Waveguides ◽  
Low Cost ◽  
Hot Embossing ◽  
Large Core ◽  
Plastic Optical Fibers ◽  
Thick Photoresist ◽  
Rectangular Groove ◽  
Flattening Process ◽  
Exposure Process

A simple and low-cost fabrication method of polymeric optical waveguides with large core sizes for plastic optical fibers is presented. The waveguides are fabricated by hot embossing with a rectangular ridge ultraviolet (UV)-cured epoxy resin stamper. The stamper is fabricated by replication of a rectangular groove mold that is made from silicone rubber replicated from a rectangular ridge original master made from thick photoresist (SU-8). A rectangular ridge shape of the original photoresist master of 1 mm size was realized by using a flattening process, which involves hot embossing before the exposure process and using a UV-cut filter during the exposure process.

A Study on Optical Fiber Damage Due to Optoelectronic Assembly Processes

2005 ◽  
Author(s):  
Kaustubh R. Nagarkar ◽  
Peter Borgesen ◽  
Krishnaswami Srihari
Keyword(s):  
Optical Fibers ◽  
Fiber Optic ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Sem Analysis ◽  
Primary Sources ◽  
Mechanical Degradation ◽  
Fiber Damage ◽  
The Individual ◽  
The Impact

Optoelectronic assembly processes, such as laser and photodiode packaging, connector assembly, and splicing, tend to involve extensive handling of optical fibers. These processes offer considerable likelihood of inducing severe damage to the fibers. Such damage degrades the strength of optical fibers and could result in lower than expected lifetimes in service. The objective of this research was to investigate the impact of fiber-optic assembly processes on the mechanical performance of optical fibers. Certain applications such as fiber-optic splices, connectors, and optoelectronic packages require that the protective coating of the fibers be removed through a process called ‘fiber-stripping’. The process of ‘fiber-stripping’ was characterized to identify the primary sources of mechanical degradation. The related handling and cleaning steps were also evaluated. Further, the process steps in the assembly of fiber optic connectors were closely examined and the impact of assembling fibers into adhesives was tested. Qualitative and quantitative tools have been used to investigate the problems and have been discussed in this paper. Tensile tests were used to compare the mechanical performance of the fibers. Special fixtures and test set-ups were created that enabled the testing of the fibers. Characterization techniques, such as Scanning Electron Microscopy (SEM) analysis and optical microscopy, were also used. The results have enabled to identify the contributions of the individual assembly steps that impair the strength of optical fibers. This paper provides an understanding of the potential sources and mechanisms of degradation due to such processes.

Accent Policy and Accent Modification Enterprises as Potential Indicators of Intercultural Power Relations: A Call for an Updated Research Agenda

2013 ◽  
Vol 3 (1) ◽  
pp. 22-33 ◽  
Author(s):  
Brynne D. Ovalle ◽  
Rahul Chakraborty
Keyword(s):  
International Relations ◽  
Identity Construction ◽  
Social Theory ◽  
Power Relations ◽  
Linguistic Diversity ◽  
Cultural Organization ◽  
Using Data ◽  
The Individual ◽  
The Impact ◽  
The Relationship

This article has two purposes: (a) to examine the relationship between intercultural power relations and the widespread practice of accent discrimination and (b) to underscore the ramifications of accent discrimination both for the individual and for global society as a whole. First, authors review social theory regarding language and group identity construction, and then go on to integrate more current studies linking accent bias to sociocultural variables. Authors discuss three examples of intercultural accent discrimination in order to illustrate how this link manifests itself in the broader context of international relations (i.e., how accent discrimination is generated in situations of unequal power) and, using a review of current research, assess the consequences of accent discrimination for the individual. Finally, the article highlights the impact that linguistic discrimination is having on linguistic diversity globally, partially using data from the United Nations Educational, Scientific and Cultural Organization (UNESCO) and partially by offering a potential context for interpreting the emergence of practices that seek to reduce or modify speaker accents.

Investigating the Relationship Between Self-Esteem and Stigma Among Young Adults With History of Suicide Attempts

Crisis ◽  
2016 ◽  
Vol 37 (4) ◽  
pp. 265-270 ◽  
Author(s):  
Meshan Lehmann ◽  
Matthew R. Hilimire ◽  
Lawrence H. Yang ◽  
Bruce G. Link ◽  
Jordan E. DeVylder
Keyword(s):  
Young Adults ◽  
Suicide Attempts ◽  
Self Esteem ◽  
High Risk Population ◽  
High Functioning ◽  
People With Mental Illness ◽  
History Of ◽  
The Individual ◽  
The Impact ◽  
The Relationship

Abstract. Background: Self-esteem is a major contributor to risk for repeated suicide attempts. Prior research has shown that awareness of stigma is associated with reduced self-esteem among people with mental illness. No prior studies have examined the association between self-esteem and stereotype awareness among individuals with past suicide attempts. Aims: To understand the relationship between stereotype awareness and self-esteem among young adults who have and have not attempted suicide. Method: Computerized surveys were administered to college students (N = 637). Linear regression analyses were used to test associations between self-esteem and stereotype awareness, attempt history, and their interaction. Results: There was a significant stereotype awareness by attempt interaction (β = –.74, p = .006) in the regression analysis. The interaction was explained by a stronger negative association between stereotype awareness and self-esteem among individuals with past suicide attempts (β = –.50, p = .013) compared with those without attempts (β = –.09, p = .037). Conclusion: Stigma is associated with lower self-esteem within this high-functioning sample of young adults with histories of suicide attempts. Alleviating the impact of stigma at the individual (clinical) or community (public health) levels may improve self-esteem among this high-risk population, which could potentially influence subsequent suicide risk.

The Role of Threat and Economic Uncertainty in Support for Scottish Independence

2014 ◽  
Vol 23 (1) ◽  
pp. 103-124 ◽  
Author(s):  
Daniel Kopasker
Keyword(s):  
Economic Consequences ◽  
Perceived Threat ◽  
Constitutional Change ◽  
Lack Of Information ◽  
Economic Expectations ◽  
Scottish Independence ◽  
The Individual ◽  
The Impact ◽  
Levels Of Support

Existing research has consistently shown that perceptions of the potential economic consequences of Scottish independence are vital to levels of support for constitutional change. This paper attempts to investigate the mechanism by which expectations of the economic consequences of independence are formed. A hypothesised causal micro-level mechanism is tested that relates constitutional preferences to the existing skill investments of the individual. Evidence is presented that larger skill investments are associated with a greater likelihood of perceiving economic threats from independence. Additionally, greater perceived threat results in lower support for independence. The impact of uncertainty on both positive and negative economic expectations is also examined. While uncertainty has little effect on negative expectations, it significantly reduces the likelihood of those with positive expectations supporting independence. Overall, it appears that a general economy-wide threat is most significant, and it is conjectured that this stems a lack of information on macroeconomic governance credentials.

Laughter on the Fringes

2019 ◽  
Author(s):  
Anna Peterson
Keyword(s):  
The Other ◽  
Literary Canon ◽  
Autobiographical Writing ◽  
Treasure Trove ◽  
Old Comedy ◽  
Other Hand ◽  
Aggressive Humor ◽  
The One ◽  
The Individual ◽  
The Impact

This book examines the impact that Athenian Old Comedy had on Greek writers of the Imperial era. It is generally acknowledged that Imperial-era Greeks responded to Athenian Old Comedy in one of two ways: either as a treasure trove of Atticisms, or as a genre defined by and repudiated for its aggressive humor. Worthy of further consideration, however, is how both approaches, and particularly the latter one that relegated Old Comedy to the fringes of the literary canon, led authors to engage with the ironic and self-reflexive humor of Aristophanes, Eupolis, and Cratinus. Authors ranging from serious moralizers (Plutarch and Aelius Aristides) to comic writers in their own right (Lucian, Alciphron), to other figures not often associated with Old Comedy (Libanius) adopted aspects of the genre to negotiate power struggles, facilitate literary and sophistic rivalries, and provide a model for autobiographical writing. To varying degrees, these writers wove recognizable features of the genre (e.g., the parabasis, its agonistic language, the stage biographies of the individual poets) into their writings. The image of Old Comedy that emerges from this time is that of a genre in transition. It was, on the one hand, with the exception of Aristophanes’s extant plays, on the verge of being almost completely lost; on the other hand, its reputation and several of its most characteristic elements were being renegotiated and reinvented.

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