The T-15MD tokamak is equipped with a gyrotron set-up, which currently includes one gyrotron with an operating output frequency of 82.6 GHz and a power of 1 MW. The length of the waveguide path from the gyrotron to th...
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Excitation equations for waveguides and cavities excited by extraneous sources are used for solving problems in electrodynamics, microwave and terahertz electronics. In some monographs authors suggest an algorithm for...
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In this study, we demonstrate direct femtosecond laser writing of -BaB2O4 crystal waveguides in the inside of 47,5BaO-5Al2O3-47,5B2O3 glass. The propagating mode profile was evaluated in the near field as Gaussian wit...
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ISBN:
(纸本)9781665418768
In this study, we demonstrate direct femtosecond laser writing of -BaB2O4 crystal waveguides in the inside of 47,5BaO-5Al2O3-47,5B2O3 glass. The propagating mode profile was evaluated in the near field as Gaussian with slightly elliptical cross-section.
Astrophotonics is a burgeoning field that lies at the interface of photonics and modern astronomical instrumentation. Here we provide a pedagogical review of basic photonic functions that enable modern instruments, an...
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Astrophotonics is a burgeoning field that lies at the interface of photonics and modern astronomical instrumentation. Here we provide a pedagogical review of basic photonic functions that enable modern instruments, and give an overview of recent and future applications. Traditionally, optical fibres have been used in innovative ways to vastly increase the multiplex advantage of an astronomical instrument, e.g. the ability to observe hundreds or thousands of stars simultaneously. But modern instruments are using many new photonic functions, some emerging from the telecom industry, and others specific to the demands of adaptive optics systems on modern telescopes. As telescopes continue to increase in size, we look to a future where instruments exploit the properties of individual photons. In particular, we envisage telescopes and interferometers that build on international developments in quantum networks, the so-called quantum internet. With the aid of entangled photons and quantum logic gates, the new infrastructures seek to preserve the photonic state and timing of individual photons over a coherent network.
Organic thin-film fluorescent sensor is an efficient tool for detecting trace chemical vapor, such as illegal drugs, explosives, nerve agents, and other dangerous substances due to its high sensitivity and quick respo...
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Organic thin-film fluorescent sensor is an efficient tool for detecting trace chemical vapor, such as illegal drugs, explosives, nerve agents, and other dangerous substances due to its high sensitivity and quick response. However, most of the current device structures rely on space optics, which makes it challenging to integrate with complementary metal oxide semiconductor (CMOS) technology, and hence difficult for achieving chip-level implementation. On the other hand, silicon nitride waveguide-based photonics have recently shown strong potential for developing commercial-scale fully integrated on-chip gas sensors. In this work, to the best of the knowledge, the first chemical vapor detector based on fluorescence sensing is reported by the evanescent field of the waveguide on integrated photonic platform. By the simultaneous excitation and collection with the same waveguide, a detection limit of 0.19 and 93.7 ppb for methamphetamine and aniline, respectively, is achieved. Thanks to the good compatibility with CMOS fabrication processes, this on-chip optical sensor can achieve production scalability as well as ease of integration with wearable electronic devices to meet the demands of portable, rapid detection. The technical route presented in this work provides a promising solution for compact, low-cost fluorescence-based gas sensors.
We present the properties and performance of fluorescentwaveguidelattices as coatings for solar cells, designed to address the significantmismatch between the solar cell's spectral response range andthe solar spec...
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We present the properties and performance of fluorescentwaveguidelattices as coatings for solar cells, designed to address the significantmismatch between the solar cell's spectral response range andthe solar spectrum. Using arrays of microscale visible light opticalbeams transmitted through photoreactive polymer resins comprisingacrylate and silicone monomers and fluorescein o,o '-dimethacrylate comonomer, we photopolymerize well-structuredfilms with single and multiple waveguide lattices. The materials exhibitedbright green-yellow fluorescence emission through down-conversionof blue-UV excitation and light redirection from the dye emissionand waveguide lattice structure. This enables the films to collecta broader spectrum of light, spanning UV-vis-NIR overan exceptionally wide angular range of +/- 70 degrees. When employedas encapsulant coatings on commercial silicon solar cells, the polymerwaveguide lattices exhibited significant enhancements in solar cellcurrent density. Below 400 nm, the primary mode of enhancement isthrough down-conversion and light redirection from the dye emissionand collection by the waveguides. Above 400 nm, the primary modesof enhancement were a combination of down-conversion, wide-angle lightcollection, and light redirection from the dye emission and collectionby the waveguides. Waveguide lattices with higher dye concentrationsproduced more well-defined structures better suited for current generationin encapsulated solar cells. Under standard AM 1.5 G irradiation,we observed nominal average current density increases of 0.7 and 1.87mA/cm(2) for single waveguide lattices and two intersectinglattices, respectively, across the full +/- 70 degrees range and revealoptimal dye concentrations and suitable lattice structures for solarcell performance. Our findings demonstrate the significant potentialof incorporating down-converting fluorescent dyes in polymer waveguidelattices for improving the current spectral and angular response ofsolar cell
Integrated photonics is a powerful contender in the race for a fault-tolerant quantum computer, claiming to be a platform capable of scaling to the necessary number of qubits. This necessitates the use of high-quality...
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Integrated photonics is a powerful contender in the race for a fault-tolerant quantum computer, claiming to be a platform capable of scaling to the necessary number of qubits. This necessitates the use of high-quality quantum states, which we create here using an all-around high-performing photon source on an integrated photonics platform. We use a photonic molecule architecture and broadband directional couplers to protect against fabrication tolerances and ensure reliable operation. As a result, we simultaneously measure a spectral purity of 99.1 +/- 0.1%, a pair generation rate of 4.4 +/- 0.1 MHz mW(-2), and an intrinsic source heralding efficiency of 94.0 +/- 2.9%. We also see a maximum coincidence-to-accidental ratio of 1644 +/- 263. We claim over an order of magnitude improvement in the trivariate trade-off among source heralding efficiency, purity, and brightness. Future implementations of the source could achieve in excess of 99% purity and heralding efficiency using the lowest reported propagation losses.
Frequency conversion in nonlinear materials is an extremely useful solution to the generation of new optical frequencies. Often, it is the only viable solution to realize light sources highly relevant for applications...
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Frequency conversion in nonlinear materials is an extremely useful solution to the generation of new optical frequencies. Often, it is the only viable solution to realize light sources highly relevant for applications in science and industry. In particular, supercontinuum generation in waveguides, defined as the extreme spectral broadening of an input pulsed laser light, is a powerful technique to bridge distant spectral regions based on single-pass geometry, without requiring additional seed lasers or temporal synchronization. Owing to the influence of dispersion on the nonlinear broadening physics, supercontinuum generation had its breakthrough with the advent of photonic crystal fibers, which permitted an advanced control of light confinement, thereby greatly improving our understanding of the underlying phenomena responsible for supercontinuum generation. More recently, maturing in fabrication of photonic integrated waveguides has resulted in access to supercontinuum generation platforms benefiting from precise lithographic control of dispersion, high yield, compact footprint, and improved power consumption. This Review aims to present a comprehensive overview of supercontinuum generation in chip-based platforms, from underlying physics mechanisms up to the most recent and significant demonstrations. The diversity of integrated material platforms, as well as specific features of waveguides, is opening new opportunities, as will be discussed here.
An efficient photorefractive effect triggered by pyroelectricity is demonstrated in slab waveguides constituted of magnesium oxide (MgO)-doped LiNbO3 film on insulator. A microwatt-level continuous wave guided at 532 ...
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An efficient photorefractive effect triggered by pyroelectricity is demonstrated in slab waveguides constituted of magnesium oxide (MgO)-doped LiNbO3 film on insulator. A microwatt-level continuous wave guided at 532 nm is self-trapped to form a 10 mu m FWHM beam triggered by only a few degrees of temperature increase of the sample. A fast self-focusing response time on the order of milliseconds is measured for milliwatts of injected beam, more than two orders of magnitude faster than in the undoped LiNbO3 film. Long lived 2-D induced waveguides are found to be written in the films.
To prevent the crosstalk between adjacent waveguides in photonic integrated circuits, the minimum thickness of the cladding layers is around half a wavelength, which imposes a fundamental limitation to further integra...
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To prevent the crosstalk between adjacent waveguides in photonic integrated circuits, the minimum thickness of the cladding layers is around half a wavelength, which imposes a fundamental limitation to further integration and miniaturization of photonic circuits. Here, we reveal that epsilon-near-zero claddings, either isotropic or anisotropic, can break the above bottleneck by prohibiting the crosstalk for the modes with magnetic field polarized in the z direction at a deep-subwavelength thickness (e.g., ? (0)/30, ? (0) is the free-space wavelength), therefore bestowing ultra-compact waveguide systems. The physical origin of this remarkable effect attributes to the divergent impedance of epsilon-near-zero materials far beyond those of dielectric or epsilon-negative claddings. Through full-wave simulations and microwave experiments, we have verified the effectiveness of the ultrathin epsilon-near-zero cladding in crosstalk prohibition. Our finding reveals the significant impact of impedance difference in waveguide designs and opens a promising route toward ultra-compact photonic chips.
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