Search for dissertations about: "Coherent"
Showing result 1 - 5 of 720 swedish dissertations containing the word Coherent.
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1. Propagation of some coherent and partially coherent laser beams
Abstract : In this thesis, we investigate the propagation of some coherent and partially coherent laser beams, including a dark hollow beam (DHB), an elliptical Gaussian beam (EGB), a flat-topped beam and a twisted anisotropic Gaussian Schell-model (TAGSM) beam, through a paraxial optical system or a turbulent atmosphere. Several theoretical models are proposed to describe a DHB of circular or non-circular symmetry. READ MORE
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2. Space Plasma Dynamics : Instabilities, Coherent Vortices and Covariant Parametrization
Abstract : The magnetospheric cusps are two funnel-like regions of Earth's magnetosphere where solar wind plasma can have direct access to the ionosphere. The cusps are very dynamic regions where wave-particle interactions continuously take place and redistribute energy among different particle populations. READ MORE
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3. Coherent Optical Transmission Systems : Performance and Coding Aspects
Abstract : Since the invention of fiber-optic systems in the 1970s, user demand has driven innovation forward, and each new generation of products has achieved higher data rates than its predecessor. Today, the most promising approach for further increasing data rates is coherent transmission with multi-level modulation and digital signal processing (DSP). READ MORE
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4. Ultrafast Coherent X-ray Diffractive Nanoimaging
Abstract : X-ray lasers are creating unprecedented research opportunities in physics,chemistry and biology. The peak brightness of these lasers exceeds presentsynchrotrons by 1010, the coherence degeneracy parameters exceedsynchrotrons by 109, and the time resolution is 105 times better. READ MORE
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5. Nonlinear Dynamics of Coherent and Partially Coherent Optical Waves
Abstract : In optics an important nonlinear effect is manifested by the fact that the refractive index, in addition to its frequency dependence, also depends on the intensity of the light. Nonlinear effects are present within a wide range of optical applications e.g. the fast growing fields of fiber-optic communication and all-optical signal processing. READ MORE