4,113 research outputs found
Characterization and modeling of microstructured chalcogenide fibers for efficient mid-infrared wavelength conversion
No full textWe experimentally demonstrate wavelength conversion in the 2 micron region by four-wave mixing in an AsSe and a GeAsSe chalcogenide photonic crystal fibers. A maximum conversion efficiency of -25.4 dB is measured for 112 mW of coupled continuous wave pump in a 27 cm long fiber. We estimate the dispersion parameters and the nonlinear refractive indexes of the chalcogenide PCFs, establishing a good agreement with the values expected from simulations. The different fiber geometries and glass compositions are compared in terms of performance, showing that GeAsSe is a more suited candidate for nonlinear optics at 2 micron. Building from the fitted parameters we then propose a new tapered GeAsSe PCF geometry to tailor the waveguide dispersion and lower the zero dispersion wavelength (ZDW) closer to the 2 mu m pump wavelength. Numerical simulations shows that the new design allows both an increased conversion efficiency and bandwidth, and the generation of idler waves further in the mid-IR regions, by tuning the pump wavelength in the vicinity of the fiber ZDW
Second- and third-order nonlinear wavelength conversion in an all-optically poled Si3N4 waveguide
No full textSilicon nitride (Si3N4) is commonly employed to integrate third-order nonlinear optical processes on a chip. Its amorphous state, however, inhibits significant second-order nonlinear response. Recently, second-harmonic generation enhancement has been observed in Si3N4 waveguides after an all-optical poling (AOP) method. Here we demonstrate that, after AOP of a Si3N4 waveguide, for up to 2 W of coupled pump power, the same telecom-band signal undergoes larger interband wavelength conversion efficiency, based on sum-frequency generation (SFG), than intraband wavelength conversion, based on four-wave mixing. We also confirm the appearance of a phase-matching condition after AOP by measuring the conversion bandwidth and efficiency of SFG at different pump wavelengths. (C) 2018 Optical Society of AmericaLPQMPHOS
Mid infrared gas spectroscopy using efficient fiber laser driven photonic chip-based supercontinuum
No full textDirectly accessing the middle infrared, the molecular functional group spectral region, via supercontinuum generation processes based on turn-key fiber lasers offers the undeniable advantage of simplicity and robustness. Recently, the assessment of the coherence of the mid-IR dispersive wave in silicon nitride (Si3N4) waveguides, pumped at telecom wavelength, established an important first step towards mid-IR frequency comb generation based on such compact systems. Yet, the spectral reach and efficiency still fall short for practical implementation. Here, we experimentally demonstrate that large cross-section Si3N4 waveguides pumped with 2 mu m fs-fiber laser can reach the important spectroscopic spectral region in the 3-4 mu m range, with up to 35% power conversion and milliwatt-level output powers. As a proof of principle, we use this source for detection of C2H2 by absorption spectroscopy. Such result makes these sources suitable candidate for compact, chip-integrated spectroscopic and sensing applications
PiLa-CS Professional Learning Community - Workshop 2 Resources
No full textDuring the Summer of 2021 and 2022, the Participating in Literacies and Computer Science (PiLa-CS) Research Practice Partnership convened and supported a community of practice to learn more about how to enable better CS teaching for emergent bilinguals. These are materials from Workshop 2 of the PLC.Sponsored by the National Science Foundation under NSF grant CNS-1738645 and DRL-1837446. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation
Translanguaging Pedagogy in CS Ed
No full textEpisode 3: Translanguaging pedagogy in CS Education
This video looks at how multilingual students already use translanguaging in their computer science classes and discusses how CS educators can further support them with translanguaging pedagogy, a framework that prompts teachers to consider their stance, design, and shifts.
Featuring team members from Participating in Literacies and Computer Science (PiLa-CS), https://www.pila-cs.orgEpisode 3: Translanguaging pedagogy in CS Education
This video looks at how multilingual students already use translanguaging in their computer science classes and discusses how CS educators can further support them with translanguaging pedagogy, a framework that prompts teachers to consider their stance, design, and shifts.
Featuring team members from Participating in Literacies and Computer Science (PiLa-CS), https://www.pila-cs.orgSponsored by the National Science Foundation under NSF grant CNS-1738645 and DRL-1837446. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation
PiLa-CS Professional Learning Community - Design Journal Template
No full textDuring the Summer of 2021 and 2022, the Participating in Literacies and Computer Science (PiLa-CS) Research Practice Partnership convened and supported a community of practice to learn more about how to enable better CS teaching for emergent bilinguals. These are materials from from the PLC for a Design Journal to act as a planing template for teachers.Sponsored by the National Science Foundation under NSF grant CNS-1738645 and DRL-1837446. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation
Arizona Then and Now: Exploring Arizona's Five Cs Through Photography
No full textabstract: Arizona Then and Now: Exploring Arizona's Five Cs Through Photography is a photographic exploration of the evolution of Arizona's five Cs: cotton, copper, citrus, cattle, and climate. This project first looks to the past to see how these five elements shaped the state of Arizona. Photographs were taken across the valley of these elements, or lack thereof, discovering what Arizona has transformed into in the process. Each chapter of the book begins with a brief history of the element focused on in that chapter, followed by an analytical thought about the photographs taken and how the element has evolved. Each chapter shows two historical photographs followed by a series of photographs taken during the project that the author thought depicted what is seen today. The book ends on a final positive note about how the five Cs are not dead, but soon could be completely taken over. This project was a way for a non-art major to explore the state that she grew up while also challenging herself by more than just taking pictures. The photographs displayed in the book depict a sampling of what the author saw that is left of the five Cs
IR-improved DGLAP-CS QCD parton showers in Pythia8
No full textAbstractWe introduce the recently developed IR-improved DGLAP-CS theory into the showers in Pythia8, as this Monte Carlo event generator is in wide use at LHC. We show that, just as it was true in the IR-improved shower Monte Carlo Herwiri, which realizes the IR-improved DGLAP-CS theory in the Herwig6.5 environment, the soft limit in processes such as single heavy gauge boson production is now more physical in the IR-improved DGLAP-CS theory version of Pythia8. This opens the way to one’s getting a comparison between the actual detector simulations for some of the LHC experiments between IR-improved and unimproved showers as Pythia8 is used in detector simulations at LHC whereas Herwig6.5, the environment of the only other IR-improved DGLAP-CS QCD MC in the literature, Herwiri1.031, is not any longer so used. Our achieving the availability of the IR-improved DGLAP-CS Pythia8 then is an important step in the further development of the LHC precision theory program under development by the author and his collaborators
What CS Ed Can Offer Bi/Multilinguals
No full textEpisode 4: What can CS offer multilingual learners?
This video discusses how computer science education can benefit multilingual learners. You will meet a middle school ENL (English as a New Language) teacher who successfully incorporated both translanguaging pedagogy and CS education into her classroom, leading to a memorable experience for one of her students.
Featuring team members from Participating in Literacies and Computer Science (PiLa-CS), https://www.pila-cs.orgEpisode 4: What can CS offer multilingual learners?
This video discusses how computer science education can benefit multilingual learners. You will meet a middle school ENL (English as a New Language) teacher who successfully incorporated both translanguaging pedagogy and CS education into her classroom, leading to a memorable experience for one of her students.
Featuring team members from Participating in Literacies and Computer Science (PiLa-CS), https://www.pila-cs.orgSponsored by the National Science Foundation under NSF grant CNS-1738645 and DRL-1837446. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation
Recent Advances on Nonlinear Optics in Silicon Nitride Waveguides
No full textNonlinear phenomena based on the material 2nd or 3rd order nonlinear susceptibility tensor χ(2) and χ(3), respectively, offer potential in a wide variety of applications by exploiting wave-mixing capabilities. The integration of these nonlinear effects at the chip scale represents the best path towards portable, compact and low power optical signal processing devices. A significant body of work has been done recently in this direction, in particular focusing on CMOS-compatible platforms. While many nonlinear effects have been demonstrated in Silicon, Silicon Nitride has recently sparked significant interest. Owing to a larger band gap, wide transparency window and low loss, the potential of SiN waveguides for linear and nonlinear optics is now well established. In this paper, we report recent results on nonlinear processes in SiN waveguides. In particular we will cover generation of an extremely broad supercontinuum extending 400 THz from the visible to 3.6 μm pumped by a turnkey telecom wavelength pulsed source. We will also report on a tunable pulse source based on dispersive wave generation in an engineered thick waveguide. Finally, we will show that SiN offers some interesting potential for χ(2) based nonlinear effects, an important step towards integrating second order nonlinearity on chip
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