Broadly tunable CW green-to-red laser source based on frequency doubling of a quantum-dot external cavity diode laser in a PPKTP waveguide

Here we present a compact tunable all-room-temperature frequency-doubling scheme, using a periodically poled potassium titanyl phosphate (PPKTP) waveguide and a QD-ECDL. A broad wavelength tunability of the second harmonic generated light (SHG) in the spectral region between 567.7 and 629.1 nm was achieved, with maximum conversion efficiencies in range of 0.34%-7.9%. The maximum output power for the SHG light was 4.11 mW at 591.5 nm, achieved for 52 mW of launched pump power at 1183 nm, resulting in a conversion efficiency of 7.9%.

Generation of CW tunable visible light by SHG of QD laser in a PPKTP waveguide

We demonstrate a CW tunable compact all-room-temperature laser system in the visible spectral region from 567.7 nm to 629.1 nm, by frequency doubling in a periodically-poled KTP waveguide crystal using a tunable quantum-dot external-cavity diode laser.

Generation of orange light from a PPKTP waveguide end-pumped by a quantum-dot tuneable laser

Here we present a compact all-room-temperature frequency-doubling scheme generating orange light, using a PPKTP waveguide and a quantum-dot external cavity diode laser (QD-ECDL). The maximum output power for the second harmonic generated light (SHG) was 1.43 mW at 613 nm, achieved for 70 mW of launched pump power at 1226 nm. This represents an important step towards a compact and wall-plug-efficient coherent orange light source, operating at room temperature.

Green-to-red tunable SHG of a quantum-dot laser in a PPKTP waveguide

Quasi-phase-matching is an important and widelyused technique in nonlinear optics enabling efficient frequency up-conversion. However, since its introduction almost half a century ago, this technique is well developed for near infrared (IR) but is intrinsically limited in spectral tunability in the visible range by the strict conditions set by the spatial modulation which compensates the momentum mismatch imposed by the dispersion. Here, we provide a fundamental generalization of quasi-phase-matching based on the utilization of a significant difference in the effective refractive indices of the high- and low-order modes in multimode waveguides. This concept enables to match the period of poling in a very broad wavelength range and opens up a new avenue for an order-ofmagnitude increase in wavelength range for frequency conversion from a single crystal. Using this approach, we demonstrate an all-room-temperature continuous-wave (CW) second harmonic generation (SHG) with over 60 nm tunability from green to red in a periodically-poled potassium titanyl phosphate (PPKTP) waveguide pumped by a single broadly-tunable quantumdot laser diode. © 2012 by Astro, Ltd.

Efficient generation of orange light by frequency-doubling of a quantum-dot laser radiation in a PPKTP waveguide

Orange light with maximum conversion efficiency exceeding 10% and CW output power of 12.04 mW, 10.45 mW and 6.24 mW has been generated at 606, 608, and 611 nm, respectively, from a frequency-doubled InAs/GaAs quantum-dot external-cavity diode laser by use of a periodically-poled KTP waveguides with different cross-sectional areas. The wider waveguide with the cross-sectional area of 4×4 μm demonstrated better results in comparison with the narrower waveguides (3×5 μm and 2×6 μm) which corresponded to lower coupling efficiency. Additional tuning of second harmonic light (between 606 and 614 nm) with similar conversion efficiency was possible by changing the crystal temperature. © 2014 Copyright SPIE.

Generation of tunable visible picosecond pulses by frequency-doubling of a quantum-dot laser in a PPKTP waveguide

We demonstrate a compact all-room-temperature picosecond laser source broadly tunable in the visible spectral region between 600 nm and 627 nm. The tunable radiation is obtained by frequency-doubling of a tunable quantum-dot external-cavity mode-locked laser in a periodically-poled KTP multimode waveguide. In this case, utilization of a significant difference in the effective refractive indices of the high- and low-order modes enables to match the period of poling in a very broad wavelength range. The maximum achieved second harmonic output peak power is 3.25 mW at 613 nm for 71.43 mW of launched pump peak power at 1226 nm, resulting in conversion efficiency of 4.55%. © 2013 Copyright SPIE.

Teams leading teams: Examining the role of leadership in multi-team systems

A major challenge of modern teams lies in the coordination of the efforts not just of individuals within a team, but also of teams whose efforts are ultimately entwined with those of other teams. Despite this fact, much of the research on work teams fails to consider the external dependencies that exist in organizational teams and instead focuses on internal or within team processes. Multi-Team Systems Theory is used as a theoretical framework for understanding teams-of-teams organizational forms (Multi-Team Systems; MTS's); and leadership teams are proposed as one remedy that enable MTS members to dedicate needed resources to intra-team activities while ensuring effective synchronization of between-team activities. Two functions of leader teams were identified: strategy development and coordination facilitation; and a model was developed delineating the effects of the two leader roles on multi-team cognitions, processes, and performance.^ Three hundred eighty-four undergraduate psychology and business students participated in a laboratory simulation that modeled an MTS; each MTS was comprised of three, two-member teams each performing distinct but interdependent components of an F-22 battle simulation task. Two roles of leader teams supported in the literature were manipulated through training in a 2 (strategy training vs. control) x 2 (coordination training vs. control) design. Multivariate analysis of variance (MANOVA) and mediated regression analysis were used to test the study's hypotheses. ^ Results indicate that both training manipulations produced differences in the effectiveness of the intended form of leader behavior. The enhanced leader strategy training resulted in more accurate (but not more similar) MTS mental models, better inter-team coordination, and higher levels of multi-team (but not component team) performance. Moreover, mental model accuracy fully mediated the relationship between leader strategy and inter-team coordination; and inter-team coordination fully mediated the effect of leader strategy on multi-team performance. Leader coordination training led to better inter-team coordination, but not to higher levels of either team or multi-team performance. Mediated Input-Process-Output (I-P-O) relationships were not supported with leader coordination; rather, leader coordination facilitation and inter-team coordination uniquely contributed to component team and multi-team level performance. The implications of these findings and future research directions are also discussed. ^

A history of a policy-level curriculum change in California

With the publication of A Nation at Risk (1983) educational reform has had a prominent place on the agenda of virtually every one of the sovereign states. As in many other states California focused much of its reform effort on the teaching of reading. In a political battle over the reading curriculum, California went from the English/Language Arts Framework of 1987, widely viewed as giving the state's imprimatur to whole language (an approach rooted in the learner's experience), to the English/Language Arts Frameworks (a more traditional or basic approach) of 1998 that called for the inclusion of phonemic awareness as the building block of reading instruction in all elementary schools. This study examined the historical record to determine the major forces behind this curriculum change. The results of this study are helpful to those who wish to better understand the relationship between political forces and curriculum change in the current age of educational reform. ^ This study utilized qualitative research methods and is presented as humanistic historical research (Landes & Tilly, 1971). The organizational framework for the study is taken from the work of M. Frances Klein (1991) which identifies seven different levels of curriculum decision-making. In this analysis particular attention was paid to the interaction of academic, formal, and societal levels, as the problem under consideration casts curriculum decision-making in the political realm. Three sources of information were used to provide the historical record. They include articles from popular newspapers and magazines, government documents, and interviews with individuals directly involved in the political process. ^ The results of this study demonstrate the power of societal forces over formal authority in making curriculum policy decisions. ^

The Battle for National History Standards

The Common Core State Standards has revived the discourse of voluntary national standards, which in the discipline of history has been extremely contentious. What is the relationship between the federal government and the formulation of national history standards? National standards could be the key to raising student achievement.

Cuba’s Role in Venezuela’s Control of the Internet and Online Social Networks

The arrival of Cuba’s Information Technology (IT) and Communications Minister Ramiro Valdés to Venezuela in the Spring of 2010 to serve as a ‘consultant’ to the Venezuelan government awakened a new reality in that country. Rampant with deep economic troubles, escalating crime, a murder rate that has doubled since Chávez took over in 1999, and an opposition movement led by university students and other activists who use the Internet as their primary weapon, Venezuela has resorted to Cuba for help. In a country where in large part traditional media outlets have been censored or are government-controlled, the Internet and its online social networks have become the place to obtain, as well as disseminate, unfiltered information. As such, Internet growth and use of its social networks has skyrocketed in Venezuela, making it one of Latin America’s highest Web users. Because of its increased use to spark political debate among Venezuelans and publish information that differs with the official government line, Chávez has embarked on an initiative to bring the Internet to the poor and others who would otherwise not have access, by establishing government-sponsored Internet Info Centers throughout the country, to disseminate information to his followers. With the help of Cuban advisors, who for years have been a part of Venezuela’s defense, education, and health care initiatives, Chávez has apparently taken to adapting Cuba’s methodology for the control of information. He has begun to take special steps toward also controlling the type of information flowing through the country’s online social networks, considering the implementation of a government-controlled single Internet access point in Venezuela. Simultaneously, in adapting to Venezuela’s Internet reality, Chávez has engaged online by creating his own Twitter account in an attempt to influence public opinion, primarily of those who browse the Web. With a rapidly growing following that may soon reach one million subscribers, Chávez claims to have set up his own online trench to wage cyber space battle.

A state of war: Florida from 1939 to 1945

World War II profoundly impacted Florida. The military geography of the State is essential to an understanding the war. The geostrategic concerns of place and space determined that Florida would become a statewide military base. Florida's attributes of place such as climate and topography determined its use as a military academy hosting over two million soldiers, nearly 15 percent of the GI Army, the largest force the US ever raised. One-in-eight Floridians went into uniform. Equally, Florida's space on the planet made it central for both defensive and offensive strategies. The Second World War was a war of movement, and Florida was a major jump off point for US force projection world-wide, especially of air power. Florida's demography facilitated its use as a base camp for the assembly and engagement of this military power. In 1940, less than two percent of the US population lived in Florida, a quiet, barely populated backwater of the United States. But owing to its critical place and space, over the next few years it became a 65,000 square mile training ground, supply dump, and embarkation site vital to the US war effort. Because of its place astride some of the most important sea lanes in the Atlantic World, Florida was the scene of one of the few Western Hemisphere battles of the war. The militarization of Florida began long before Pearl Harbor. The pre-war buildup conformed to the US strategy of the war. The strategy of theUS was then (and remains today) one of forward defense: harden the frontier, then take the battle to the enemy, rather than fight them in North America. The policy of "Europe First," focused the main US war effort on the defeat of Hitler's Germany, evaluated to be the most dangerous enemy. In Florida were established the military forces requiring the longest time to develop, and most needed to defeat the Axis. Those were a naval aviation force for sea-borne hostilities, a heavy bombing force for reducing enemy industrial states, and an aerial logistics train for overseas supply of expeditionary campaigns. The unique Florida coastline made possible the seaborne invasion training demanded for US victory. The civilian population was employed assembling mass-produced first-generation container ships, while Floridahosted casualties, Prisoners-of-War, and transient personnel moving between the Atlantic and Pacific. By the end of hostilities and the lifting of Unlimited Emergency, officially on December 31, 1946, Floridahad become a transportation nexus. Florida accommodated a return of demobilized soldiers, a migration of displaced persons, and evolved into a modern veterans' colonia. It was instrumental in fashioning the modern US military, while remaining a center of the active National Defense establishment. Those are the themes of this work.

Fractional order of poling period for broadly tunable second harmonic generation

We demonstrate the possibility to use a fractional order of poling period of nonlinear crystal waveguides for tunable second harmonic generation. This approach allows one to extend wavelength coverage in the visible spectral range by frequency doubling in a single crystal waveguide.

Map of n. eastern Virginia and vicinity of Washington /

Relief shown by hachures. Depths shown by soundings.

A State of War: Florida from 1939 to 1945

World War II profoundly impacted Florida. The military geography of the State is essential to an understanding the war. The geostrategic concerns of place and space determined that Florida would become a statewide military base. Florida’s attributes of place such as climate and topography determined its use as a military academy hosting over two million soldiers, nearly 15 percent of the GI Army, the largest force theUS ever raised. One-in-eight Floridians went into uniform. Equally,Florida’s space on the planet made it central for both defensive and offensive strategies. The Second World War was a war of movement, and Florida was a major jump off point forUSforce projection world-wide, especially of air power. Florida’s demography facilitated its use as a base camp for the assembly and engagement of this military power. In 1940, less than two percent of the US population lived in Florida, a quiet, barely populated backwater of the United States.[1] But owing to its critical place and space, over the next few years it became a 65,000 square mile training ground, supply dump, and embarkation site vital to the US war effort. Because of its place astride some of the most important sea lanes in the Atlantic World,Florida was the scene of one of the few Western Hemisphere battles of the war. The militarization ofFloridabegan long before Pearl Harbor. The pre-war buildup conformed to theUSstrategy of the war. The strategy of theUS was then (and remains today) one of forward defense: harden the frontier, then take the battle to the enemy, rather than fight them inNorth America. The policy of “Europe First,” focused the main US war effort on the defeat of Hitler’sGermany, evaluated to be the most dangerous enemy. In Florida were established the military forces requiring the longest time to develop, and most needed to defeat the Axis. Those were a naval aviation force for sea-borne hostilities, a heavy bombing force for reducing enemy industrial states, and an aerial logistics train for overseas supply of expeditionary campaigns. The unique Florida coastline made possible the seaborne invasion training demanded for USvictory. The civilian population was employed assembling mass-produced first-generation container ships, while Floridahosted casualties, Prisoners-of-War, and transient personnel moving between the Atlantic and Pacific. By the end of hostilities and the lifting of Unlimited Emergency, officially on December 31, 1946, Floridahad become a transportation nexus. Florida accommodated a return of demobilized soldiers, a migration of displaced persons, and evolved into a modern veterans’ colonia. It was instrumental in fashioning the modern US military, while remaining a center of the active National Defense establishment. Those are the themes of this work. [1] US Census of Florida 1940. Table 4 – Race, By Nativity and Sex, For the State. 14.

Hunting the Beast on YouTube : The framing of nature in social media

Humans’ perceived relationship to nature and non-human lifeforms is fundamental for sustainable development; different framings of nature – as commodity, as threat, as sacred etc. – imply different responses to future challenges. The body of research on nature repre-sentations in various symbolic contexts is growing, but the ways in which nature is framed by people in the everyday has received scant attention. This paper aims to contribute to our understanding of the framing of nature by studying how wild-boar hunting is depicted on YouTube. The qualitative frame analysis identified three interrelated frames depicting hunting as battle, as consumption, and as privilege, all of which constitute and are constituted by the underlying notion of human as superior to nature. It is suggested that these hegemonic nature frames suppress more constructive ways of framing the human-nature relationship, but also that the identification of such potential counter-hegemonic frames enables their discursive manifestation.