79 research outputs found
Beyond solid-state lighting: Miniaturization, hybrid integration, and applications og GaN nano- and micro-LEDs
Gallium Nitride (GaN) light-emitting-diode (LED) technology has been the revolution in modern lighting. In the last decade, a huge global market of efficient, long-lasting and ubiquitous white light sources has developed around the inception of the Nobel-price-winning blue GaN LEDs. Today GaN optoelectronics is developing beyond lighting, leading to new and innovative devices, e.g. for micro-displays, being the core technology for future augmented reality and visualization, as well as point light sources for optical excitation in communications, imaging, and sensing. This explosion of applications is driven by two main directions: the ability to produce very small GaN LEDs (microLEDs and nanoLEDs) with high efficiency and across large areas, in combination with the possibility to merge optoelectronic-grade GaN microLEDs with silicon microelectronics in a fully hybrid approach. GaN LED technology today is even spreading into the realm of display technology, which has been occupied by organic LED (OLED) and liquid crystal display (LCD) for decades. In this review, the technological transition towards GaN micro- and nanodevices beyond lighting is discussed including an up-to-date overview on the state of the art
Outlook for inverse design in nanophotonics
Recent advancements in computational inverse design have begun to reshape the
landscape of structures and techniques available to nanophotonics. Here, we
outline a cross section of key developments at the intersection of these two
fields: moving from a recap of foundational results to motivation of emerging
applications in nonlinear, topological, near-field and on-chip optics.Comment: 13 pages, 6 figure
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Optimizing Nanophotonics: from Photoreceivers to Waveguides
Optical communication systems are replacing electrical interconnects on shorter and shorter scales, thanks to the large bandwidth they can provide and their better energy efficiency over long distances. Optical circuit boards or even on-chip interconnects are becoming an increasingly attractive possibility, thanks to tighter integration of photonics and electronics in technology platforms such as Silicon photonics. Nevertheless in order for optical links to become competitive with their electrical counterparts at these very short length scales, their energy efficiency must still be drastically improved. State of the art systems today consume ~1pJ/bit of energy to communicate information, which is orders of magnitude above theoretical bounds.In this thesis, the discrepancies between the theoretical limits and real world perfor- mance are explored, with a focus on the photoreceiver, which dictates the sensitivity and therefore much of the energy used by the link.A thorough modeling of optical links is performed, leading to the determination of optimal receiver circuit topologies to improve the sensitivity and reduce the power con- sumption of photoreceiver systems. This enables the identification of crucial performance bottlenecks and the establishment of a technological roadmap for future generations of optical interconnects.Additionally an extremely efficient shape optimization technique using the adjoint method for passive nanophotonics is presented, in order to provide lower loss components thereby also offering a path to improve the performance of optical links
Estimation de l'évolution de l'artificialisation des terres à l'échelle départementale par télédétection : le cas de l'Ille et Vilaine
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