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Doppler broadening
About: Doppler broadening is a research topic. Over the lifetime, 5509 publications have been published within this topic receiving 92552 citations.
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TL;DR: In this article, the authors studied the formation of turbulence of capillary waves in laboratory experiments and showed that the instability leads to spectral broadening of the harmonics, randomization of their phases, it isolates the wave field from the wall, eventually allows the transition from 4-to 3-wave interactions as the dominant nonlinear process, thus creating the prerequisites assumed in weak turbulence theory.
Abstract: Formation of turbulence of capillary waves is studied in laboratory experiments. The spectra show multiple exponentially decreasing harmonics of the parametrically excited wave which nonlinearly broaden with the increase in forcing. Spectral broadening leads to the development of the spectral continuum which scales as ∝f− 2.8, in agreement with the weak turbulence theory (WTT). Modulation instability of capillary waves is shown to be responsible for the transition from discrete to broadband spectrum. The instability leads to spectral broadening of the harmonics, randomization of their phases, it isolates the wave field from the wall, eventually allows the transition from 4- to 3-wave interactions as the dominant nonlinear process, thus creating the prerequisites assumed in WTT.
37 citations
TL;DR: The spectral broadening mechanism can be generalized to other frequency bands by employing different spacing materials such as silicon nitride and polydimethylsiloxane and can be useful for designing spectrally selective thermal detectors and thermal emitters.
Abstract: Here we numerically and experimentally explore the rich phenomena in the optical responses and local electromagnetic fields of a MIM absorber mediated by the dispersive spacer. We first show that the line shape of the spectral absorption is strongly modified by the interaction between the plasmonic resonances and the optical phonons in the silicon dioxide spacer. Importantly, broadening the spectral absorption in the long wave infrared range is achieved by tuning the strength of coupling. Modification to the local electromagnetic field distribution in the epsilon-near-zero region is also numerically studied. The incident-angle dependence and polarization dependence of the broadened absorption spectrum are evaluated. We also show that the spectral broadening mechanism can be generalized to other frequency bands by employing different spacing materials such as silicon nitride and polydimethylsiloxane. Our results can be useful for designing spectrally selective thermal detectors and thermal emitters.
36 citations
TL;DR: In this article, an approximate general treatment is given for the effect of electric field on the absorption edges of insulating crystals, taking into account electron-hole and carrier-lattice interactions.
36 citations
TL;DR: In this paper, the absorption and electroabsorption (Stark) spectra of eight carotenoids with different molecular structures were derived from glassy solvents and in poly(methyl methacrylate) films at temperatures 108-115 K.
36 citations
TL;DR: This Letter reports on an all-fiber-integrated master-oscillator, power amplifier system at 1.55 μm producing 5-ns, 100-μJ pulses, where the beam is truly diffraction limited, which was independently proven by M2 measurements.
Abstract: This Letter reports on an all-fiber-integrated master-oscillator, power amplifier system at 1.55 μm producing 5-ns, 100-μJ pulses. These pulses are generated at a 100 kHz repetition rate, corresponding to 10 W of average power. The seed source is a low-power, current-modulated, single-frequency, distributed feedback semiconductor laser. System output is obtained from a standard single-mode fiber (Corning SMF-28). Consequently, the beam is truly diffraction limited, which was independently proven by M2 measurements. Further increase of peak power is limited by onset of significant spectral broadening due to nonlinear effects, primarily four-wave mixing. Numerical simulations based on six-level rate equations with full position- and time-dependence were developed to model propagation of pulses through the amplifier chain. This capability allows minimization of the amplified spontaneous emission, which can be directly measured using a fast acousto-optic modulator to gate the pulses.
36 citations