10,412 research outputs found

    A Hamiltonian treatment of stimulated Brillouin scattering in nanoscale integrated waveguides

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    We present a multimode Hamiltonian formulation for the problem of opto-acoustic interactions in optical waveguides. We establish a Hamiltonian representation of the acoustic field and then introduce a full system with a simple opto-acoustic coupling that includes both photoelastic/electrostrictive and radiation pressure/moving boundary effects. The Heisenberg equations of motion are used to obtain coupled mode equations for quantized envelope operators for the optical and acoustic fields. We show that the coupling coefficients obtained coincide with those established earlier, but our formalism provides a much simpler demonstration of the connection between radiation pressure and moving boundary effects than in previous work [C. Wolff et al, Physical Review A 92, 013836 (2015)].Comment: 39 pages: 20 pages for main article + 19 pages supplementary information; 3 figure

    Bayesian modelling of skewness and kurtosis with two-piece scale and shape distributions

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    We formalise and generalise the definition of the family of univariate double two--piece distributions, obtained by using a density--based transformation of unimodal symmetric continuous distributions with a shape parameter. The resulting distributions contain five interpretable parameters that control the mode, as well as the scale and shape in each direction. Four-parameter subfamilies of this class of distributions that capture different types of asymmetry are discussed. We propose interpretable scale and location-invariant benchmark priors and derive conditions for the propriety of the corresponding posterior distribution. The prior structures used allow for meaningful comparisons through Bayes factors within flexible families of distributions. These distributions are applied to data from finance, internet traffic and medicine, comparing them with appropriate competitors
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