scholarly journals Advances in Conjugated Polymer Lasers

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 443 ◽  
Author(s):  
Hongyan Xia ◽  
Chang Hu ◽  
Tingkuo Chen ◽  
Dan Hu ◽  
Muru Zhang ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Cross Sections ◽  
Conjugated Polymer ◽  
Low Cost ◽  
Research Direction ◽  
Stimulated Emission ◽  
Laser Materials ◽  
Radiation Mechanism ◽  
The Subject ◽  
Low Cost Manufacturing

This paper provides a review of advances in conjugated polymer lasers. High photoluminescence efficiencies and large stimulated emission cross-sections coupled with wavelength tunability and low-cost manufacturing processes make conjugated polymers ideal laser gain materials. In recent years, conjugated polymer lasers have become an attractive research direction in the field of organic lasers and numerous breakthroughs based on conjugated polymer lasers have been made in the last decade. This paper summarizes the recent progress of the subject of laser processes employing conjugated polymers, with a focus on the photoluminescence principle and excitation radiation mechanism of conjugated polymers. Furthermore, the effect of conjugated polymer structures on the laser threshold is discussed. The most common polymer laser materials are also introduced in detail. Apart from photo-pumped conjugated polymer lasers, a direction for the future development of electro-pumped conjugated polymer lasers is proposed.

Fabrication Technologies for Advanced Heat Transfer Applications

2003 ◽  
Author(s):  
William J. Grande
Keyword(s):  
Heat Transfer ◽  
Emerging Technologies ◽  
Low Cost ◽  
High Volume ◽  
The Subject ◽  
Active Research ◽  
High Level ◽  
Low Cost Manufacturing ◽  
Conventional Machining ◽  
Microchannel Devices

Microchannel devices with channel widths in the range from one micron to several hundred microns have become increasingly important structures for heat transfer applications. This paper will examine several classes of fabrication technologies that are employed in the field. Established technologies, such as bulk and surface micromachining, high aspect ratio machining, and conventional machining have been perfected over the last several decades and are the principal methods of creating microchannel structures. Synthesizing technologies, such as wafer bonding and micromolding techniques, allow these primary structures to be assembled together into working devices or enable high volume, low cost manufacturing using microstructured masters. Established and synthesizing technologies have reached a high level of performance and are generally the subject of refinement efforts rather than innovative investigations. Active research into new materials, processes, and fabrication strategies are found in the class of emerging technologies. This paper will briefly review the dimensional spectrum of microchannels and survey the established and synthesizing technologies. Then an exploration of emerging technologies will be made. The topic of rapid prototyping will be given particular emphasis.

UV-Visible Lasers Based on Rare-Earth Ions

MRS Bulletin ◽  
1999 ◽  
Vol 24 (9) ◽  
pp. 21-26 ◽  
Author(s):  
R. Moncorgé ◽  
L.D. Merkle ◽  
B. Zandi
Keyword(s):  
Rare Earth ◽  
Cross Sections ◽  
Near Infrared ◽  
Yttrium Aluminum Garnet ◽  
Energy Levels ◽  
Wavelength Region ◽  
Rare Earth Ions ◽  
Stimulated Emission ◽  
Laser Materials ◽  
Visible Wavelengths

An issue on novel applications of materials doped with rare-earth (RE) ions can scarcely fail to address lasers, but it need not address all RE-based lasers. Some Nd3+ -doped lasers, particularly Nd:YAG (Y3Al5O12, yttrium aluminum garnet), emitting light with a wavelength of 1064 nm, are very well-established commercial products—by no means novelties.1 Some other near-infrared (NIR) lasers, based on Er3+ or Tm3+, are also available commercially. That wavelength region is relatively easy for RE laser ions, involving energy spacings between initial and final energy levels small enough to give large stimulated emission cross sections for useful, long upper-state life-times, yet large enough to minimize thermal deexcitation mechanisms. On the other hand, RE-doped lasers for ultraviolet (UV) and visible wavelengths are quite novel, since efficient laser operation is more difficult to achieve in these spectral ranges. Intriguing progress on such devices has been made in recent years, driven by several important applications.In this article, we begin by noting some of the alternative ways to obtain laser light at these wavelengths, including their advantages and drawbacks. We then discuss basic properties of RE-doped laser materials and how these can be advantageous. We then review a few of the most important and recent RE-doped laser materials and techniques for obtaining UV and visible output.

scholarly journals Charge Accumulation of Amplified Spontaneous Emission in a Conjugated Polymer Chain and Its Dynamical Phonon Spectra

Molecules ◽  
2020 ◽  
Vol 25 (13) ◽  
pp. 3003
Author(s):  
Zhe Lin ◽  
Jiahao Chen ◽  
Yusong Zhang ◽  
Jianguo Shen ◽  
Sheng Li ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Spontaneous Emission ◽  
Polymer Chain ◽  
Conjugated Polymer ◽  
Optical Pumping ◽  
Amplified Spontaneous Emission ◽  
Electric Polarization ◽  
Stimulated Emission ◽  
Charge Accumulation ◽  
Phonon Spectra

In this article, the detailed photoexcitation dynamics which combines nonadiabatic molecular dynamics with electronic transitions shows the occurrence of amplified spontaneous emission (ASE) in conjugated polymers, accompanied by spontaneous electric polarization. The elaborate molecular dynamic process of ultrafast photoexcitation can be described as follows: Continuous external optical pumping (laser of 70 µJ/cm2) not only triggers the appearance of an instantaneous four-level electronic structure but causes population inversion for ASE as well. At the same time, the phonon spectrum of the conjugated polymer changes, and five local infrared lattice vibrational modes form at the two ends, which break the original symmetry in the system and leads to charge accumulation at the ends of the polymer chain without an external electric field. This novel phenomenon gives a brand-new avenue to explain how the lattice vibrations play a role in the evolution of the stimulated emission, which leads to an ultrafast effect in solid conjugated polymers.

scholarly journals Highly Selective Ultrafast Circularly Polarized Photodiodes Based on π-Conjugated Polymers

2021 ◽  
Author(s):  
Matthew Ward ◽  
Jess Wade ◽  
Xingyuan Shi ◽  
Jenny Nelson ◽  
Alasdair Campbell ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Optical Communication ◽  
Conjugated Polymer ◽  
Dynamic Range ◽  
Low Cost ◽  
Linear Dynamic Range ◽  
Circularly Polarized ◽  
Molecular Systems ◽  
Fast Switching ◽  
Dark Currents

Chiral π-conjugated molecular systems that are intrinsically sensitive to the handedness of circularly polarized (CP) light potentially allow for miniaturized, low-cost CP detection devices. Such devices promise to transform several technologies, including biosensing, quantum optics and communication of data encrypted by exploiting the spin angular momentum of light. Here we realize a simple, bilayer organic photodiode (CP OPD) comprising an achiral π-conjugated polymer–chiral additive blend as the electron donor layer and an achiral C<sub>60</sub> electron acceptor layer. These devices exhibit considerable photocurrent dissymmetry <i>g</i><sub>ph</sub>, with absolute values as high as 0.85 and dark currents as low as 10 pA. Impressively, they showcase a linear dynamic range of 80 dB, and rise and fall times of 50 and 270 ns respectively, which significantly outperforms all previously reported CP selective photodetectors. Mechanistically, we show that the <i>g</i><sub>ph</sub> is sensitive to the thickness of <i>both</i> the chiral donor and achiral acceptor layers and that a trade-off exists between the external quantum efficiency (EQE) and <i>g</i><sub>ph</sub>. The fast-switching speeds of these devices, coupled with their large dynamic range and highly selective response to CP light, opens up the possibility of their direct application in CP sensing and optical communication.

scholarly journals Highly Selective Ultrafast Circularly Polarized Photodiodes Based on π-Conjugated Polymers

2021 ◽  
Author(s):  
Matthew Ward ◽  
Jess Wade ◽  
Xingyuan Shi ◽  
Jenny Nelson ◽  
Alasdair Campbell ◽  
...  
Keyword(s):  
Conjugated Polymers ◽  
Optical Communication ◽  
Conjugated Polymer ◽  
Dynamic Range ◽  
Low Cost ◽  
Linear Dynamic Range ◽  
Circularly Polarized ◽  
Molecular Systems ◽  
Fast Switching ◽  
Dark Currents

Chiral π-conjugated molecular systems that are intrinsically sensitive to the handedness of circularly polarized (CP) light potentially allow for miniaturized, low-cost CP detection devices. Such devices promise to transform several technologies, including biosensing, quantum optics and communication of data encrypted by exploiting the spin angular momentum of light. Here we realize a simple, bilayer organic photodiode (CP OPD) comprising an achiral π-conjugated polymer–chiral additive blend as the electron donor layer and an achiral C<sub>60</sub> electron acceptor layer. These devices exhibit considerable photocurrent dissymmetry <i>g</i><sub>ph</sub>, with absolute values as high as 0.85 and dark currents as low as 10 pA. Impressively, they showcase a linear dynamic range of 80 dB, and rise and fall times of 50 and 270 ns respectively, which significantly outperforms all previously reported CP selective photodetectors. Mechanistically, we show that the <i>g</i><sub>ph</sub> is sensitive to the thickness of <i>both</i> the chiral donor and achiral acceptor layers and that a trade-off exists between the external quantum efficiency (EQE) and <i>g</i><sub>ph</sub>. The fast-switching speeds of these devices, coupled with their large dynamic range and highly selective response to CP light, opens up the possibility of their direct application in CP sensing and optical communication.

Geological Field Sketches and Illustrations

2019 ◽  
Author(s):  
Matthew J. Genge
Keyword(s):  
Cross Sections ◽  
Earth Science ◽  
Three Dimensional ◽  
Worked Examples ◽  
Scientific Publications ◽  
Thin Sections ◽  
Geological Features ◽  
Different Types ◽  
The Subject

Drawings, illustrations, and field sketches play an important role in Earth Science since they are used to record field observations, develop interpretations, and communicate results in reports and scientific publications. Drawing geology in the field furthermore facilitates observation and maximizes the value of fieldwork. Every geologist, whether a student, academic, professional, or amateur enthusiast, will benefit from the ability to draw geological features accurately. This book describes how and what to draw in geology. Essential drawing techniques, together with practical advice in creating high quality diagrams, are described the opening chapters. How to draw different types of geology, including faults, folds, metamorphic rocks, sedimentary rocks, igneous rocks, and fossils, are the subjects of separate chapters, and include descriptions of what are the important features to draw and describe. Different types of sketch, such as drawings of three-dimensional outcrops, landscapes, thin-sections, and hand-specimens of rocks, crystals, and minerals, are discussed. The methods used to create technical diagrams such as geological maps and cross-sections are also covered. Finally, modern techniques in the acquisition and recording of field data, including photogrammetry and aerial surveys, and digital methods of illustration, are the subject of the final chapter of the book. Throughout, worked examples of field sketches and illustrations are provided as well as descriptions of the common mistakes to be avoided.

scholarly journals Temperature-Dependent Stimulated Emission Cross-Section in Nd3+:YLF Crystal

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 431
Author(s):  
Giorgio Turri ◽  
Scott Webster ◽  
Michael Bass ◽  
Alessandra Toncelli
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Room Temperature ◽  
Radiative Decay ◽  
Emission Cross Section ◽  
Spectroscopic Properties ◽  
Stimulated Emission ◽  
Different Temperatures ◽  
Stimulated Emission Cross Section ◽  
Semi Empirical

Spectroscopic properties of neodymium-doped yttrium lithium fluoride were measured at different temperatures from 35 K to 350 K in specimens with 1 at% Nd3+ concentration. The absorption spectrum was measured at room temperature from 400 to 900 nm. The decay dynamics of the 4F3/2 multiplet was investigated by measuring the fluorescence lifetime as a function of the sample temperature, and the radiative decay time was derived by extrapolation to 0 K. The stimulated-emission cross-sections of the transitions from the 4F3/2 to the 4I9/2, 4I11/2, and 4I13/2 levels were obtained from the fluorescence spectrum measured at different temperatures, using the Aull–Jenssen technique. The results show consistency with most results previously published at room temperature, extending them over a broader range of temperatures. A semi-empirical formula for the magnitude of the stimulated-emission cross-section as a function of temperature in the 250 K to 350 K temperature range, is presented for the most intense transitions to the 4I11/2 and 4I13/2 levels.

Strategies and concepts in n-doped conjugated polymer thermoelectrics

2021 ◽  
Vol 9 (9) ◽  
pp. 5149-5163
Author(s):  
Teck Lip Dexter Tam ◽  
Jianwei Xu
Keyword(s):  
Conjugated Polymers ◽  
Conjugated Polymer ◽  
Chemical Structure ◽  
Structure Engineering

In this review, we discuss strategies & concepts in chemical structure engineering for n-type conjugated polymers & n-dopants that have brought about huge improvements in the performance of n-doped conjugated polymer thermoelectrics in recent years.

scholarly journals Synthesis and characterization of an electron-deficient conjugated polymer based on pyridine-flanked diketopyrrolopyrrole

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12995-13003
Author(s):  
Jialin Yang ◽  
Li Yang ◽  
Qianqian Chen ◽  
Keke Guo ◽  
Ji-Min Han
Keyword(s):  
Conjugated Polymers ◽  
Electrochemical Properties ◽  
Conjugated Polymer ◽  
Synthesis And Characterization

We report a pyridine-flanked diketopyrrolopyrrole monomer and all-acceptor conjugated polymers synthesized therefrom. Photophysical, thermal and electrochemical properties of the polymers have been determined.

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