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Interaction of two counterpropagating laser induced plasmas and shock waves in air
摘要： The interaction of two counterpropagating plasmas and shockwaves due to a 7 ns laser induced breakdown (LIB) of ambient atmospheric air was studied using the 2D emission and shadowgraphic imaging technique. The effect of separation distance (d) between the two plasma sources and their energy ratio on plasma and shockwave evolution is presented. These low density and low temperature plasma sources form a stagnation layer in the interaction zone that showed an interesting dependence on the input energy of the sources. The interaction dynamics of the two counterpropagating plasma plumes and the shock waves in ambient air are compared with that of the respective single plasma source to explicitly bring out the energy exchange during the interaction. The evolution of a plasma jetlet, studied by 2D emission images and shadowgraphic imaging, has shown very good correlation giving valuable insight into the role of a plasma induced shockwave on the expanding plasma. The propagation of the shock front of the high energy source through the plasma of a low energy source is observed to predominantly lead to the formation of a jetlet and its evolution.
关键词： laser induced plasmas,plasma jetlet,plasma interaction,shock waves,counterpropagating,stagnation layer
更新于2025-09-23 15:19:57
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Nonlinear Fiber Optics || Cross-phase modulation
摘要： So far we have focused on optical pulses whose spectrum is centered at a single wavelength. When two or more pulses, launched at different wavelengths, propagate simultaneously inside a fiber, they interact with each other through the fiber’s nonlinearity. In general, such an interaction can generate new waves under appropriate conditions through a variety of nonlinear phenomena such as stimulated Raman or Brillouin scattering and four-wave mixing; these are discussed in Chapters 8 to 10. The nonlinearity can also couple two optical fields through cross-phase modulation (XPM), without inducing any energy transfer between them [1]. The XPM phenomenon is discussed in this chapter. A set of two coupled nonlinear Schr?dinger (NLS) equations is derived in Section 7.1, assuming that each wave maintains its state of polarization. These equations are used in Section 7.2 to discuss how the XPM affects the phenomenon of modulation instability. Section 7.3 focuses on the soliton pairs whose members support each other through their XPM-mediated nonlinear interaction. The effects of XPM on the shape and the spectrum of ultrashort pulses are described in Section 7.4 by solving the coupled NLS equations. Several applications of XPM are discussed in Section 7.5. A vector theory of XPM is developed in Section 7.6 to account for the polarization effects. In Section 7.7 we extend this theory to the case of birefringent fibers. The case of two counterpropagating waves is discussed in Section 7.8.
关键词： modulation instability,soliton pairs,counterpropagating waves,birefringent fibers,polarization effects,ultrashort pulses,nonlinear Schr?dinger equations,cross-phase modulation
更新于2025-09-12 10:27:22
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Counterpropagating continuous-variable entangled states in lossy coupled-cavity optical waveguides
摘要： We present an integrated source of counterpropagating entangled states based on a coupled resonator optical waveguide that is pumped by a classical pulsed source incident from above the waveguide. We investigate theoretically the generation and propagation of continuous-variable entangled states in this coupled-cavity system in the presence of intrinsic loss. Using a tight-binding approximation, we derive analytic time-dependent expressions for the number of photons in each cavity, as well as for the correlation variance between the photons in different pairs of cavities, to evaluate the degree of quantum entanglement. We also derive simple approximate expressions for these quantities that can be used to guide the design of such systems, and discuss how pumping configurations and physical properties of the system affect the photon statistics and the degree of quantum correlation.
关键词： quantum entanglement,lossy coupled-cavity optical waveguides,continuous-variable entangled states,counterpropagating,tight-binding approximation
更新于2025-09-11 14:15:04