Recent advances in solid-state organic lasers

Organic solid-state lasers are reviewed, with a special emphasis on works published during the last decade. Referring originally to dyes in solid-state polymeric matrices, organic lasers also include the rich family of organic semiconductors, paced by the rapid development of organic light emitting diodes. Organic lasers are broadly tunable coherent sources are potentially compact, convenient and manufactured at low-costs. In this review, we describe the basic photophysics of the materials used as gain media in organic lasers with a specific look at the distinctive feature of dyes and semiconductors. We also outline the laser architectures used in state-of-the-art organic lasers and the performances of these devices with regard to output power, lifetime, and beam quality. A survey of the recent trends in the field is given, highlighting the latest developments in terms of wavelength coverage, wavelength agility, efficiency and compactness, or towards integrated low-cost sources, with a special focus on the great challenges remaining for achieving direct electrical pumping. Finally, we discuss the very recent demonstration of new kinds of organic lasers based on polaritons or surface plasmons, which open new and very promising routes in the field of organic nanophotonics

Photonic mode dispersion of a two-dimensional distributed feedback polymer laser

G. A. Turnbull, P. Andrew, William L. Barnes, and I. D. W. Samuel, Physical Review B, Vol. 67, article 165107 (2003). "Copyright © 2003 by the American Physical Society."We present an analysis of the photonic mode dispersion of a two-dimensional (2D) distributed feedback polymer laser based on the conjugated polymer poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene]. We use a combination of a simple model, together with experimental measurements of the photonic mode dispersion in transmission and emission, to explain the operating characteristics of the laser. The laser was found to oscillate at 636 nm on one edge of a photonic stop band in the photonic dispersion. A 2D coupling of modes traveling perpendicular to the orthogonal gratings was found to lead to a low divergence laser emission normal to the waveguide. At pump energies well above the oscillation threshold for this mode, a divergent, cross-shaped far-field emission was observed, resulting from a distributed feedback occurring over a wide range of wave vectors in one band of the photonic dispersion

Recent Advances in Conjugated Polymers for Light Emitting Devices

A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review

ARISTOTLE ON PRINCIPLE JUSTIFICATION

Aristotelian sciences threaten to cause a great scientific scandal. A finished Aristotelian science is a deductive system of all the truths in a domain structured into theorems and the explanatory first principles (axioms, in modern parlance) that they can be explanatorily derived from. But why think these propositions (and not others) are the basic explainers? Until we get such justification, the entire science is on shaky footing. Frege called this the great scientific ‘scandal’. I argue that Aristotle theorized and in his own scientific writings practiced a strategy to overcome it. I call his strategy the downstream-justification of principles as principles. The basic idea is this: when we already accept a proposition Q which belongs to a science, and another proposition P gives an explanation for Q but does not itself have an explanation, P is a good candidate for a first principle. Downstream-justification has not received recognition from scholars. The most salient way in which this lack of recognition has been detrimental to our understanding of Aristotle is that it has prevented us from seeing how he structures his own writings. I show that downstream-justification of principles is the key to making sense of the organization of two of the most important but also most difficult Aristotelian treatises: the Physics and the Posterior Analytics.They are the conceptual entryway into much of Aristotle’s philosophy and yet are commonly thought to be some of his most chaotic, frustrating, and unsatisfying texts. I show that these treatises are in fact organized in a compelling way around a philosophically interesting project: building up sciences from scratch. I accordingly defend three main claims: (1): Aristotle Theorized A Strategy Called Downstream-Justification of Principles as Principles With Which to Overcome the Great Scientific Scandal. (ch.1) (2):The Framework Of Science-Building, And Especially Downstream- Justification Of Principles As Principles Holds The Key To The Structure Of Important Sections of Aristotle’s Foundational Work Of Natural Science, The Physics. (chs.2&3) (3): Epistemology Itself Is A Science. The Posterior Analytics, Aristotle’s Treatise On Epistemology, Records The Efforts Of A Budding Scientist To Identify And Justify Principles Of Epistemology. (ch.4