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Register a new userThermally driven continuous-wave and pulsed optical vortex
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We demonstrated the continuous-wave (cw) and pulsed optical vortex with topological charges driven by heat generated during the lasing process without introducing the astigmatism effect and reducing lasing efficiency. During the lasing process, the topological charges were changeable by the thermal-induced lens and selected by the mode-matching between the pump and oscillating beams. With a graphene sample as the saturable absorber, the pulsed optical vortex was achieved at the wavelength of 1.36 {mu}m, which identified that graphene could be used as a pulse modulator for the generation of pulsed optical vortex. It could be believed that the thermally driven cw and pulsed optical vortex should have various promising applications based on the compact structure, changeable topological charges and specific wavelength
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We demonstrate numerically novel mechanism providing generation of the flat-top solitonic pulses, platicons, in optical microresonators at normal GVD via negative thermal effects. We found that platicon excitation is possible if the ratio of the photon lifetime to the thermal relaxation time is large enough. We show that there are two regimes of the platicon generation depending on the pump amplitude: the smooth one and the oscillatory one. Parameter ranges providing platicon excitation are found and analysed for different values of the thermal relaxation time, frequency-scan rate and GVD coefficient. Possibility of the turn-key generation regime is also shown.
We analyze two-component spatial optical vortex solitons supported by parametric wave mixing processes in a nonlinear bulk medium. We study two distinct cases of such localised waves, namely, parametric vortex solitons due to phase-matched second-harmonic generation in an optical medium with competing quadratic and cubic nonlinear response, and vortex solitons in the presence of third-harmonic generation in a cubic medium. We find, analytically and numerically, the structure of two-component vortex solitons, and also investigate modulational instability of their plane-wave background. In particular, we predict and analyze in detail novel types of vortex solitons, a `halo-vortex, consisting of a two-component vortex core surrounded by a bright ring of its harmonic field, and a `ring-vortex soliton which is a vortex in a harmonic field that guides a ring-like localized mode of the fundamental-frequency field.
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We present the theory of modulation instability induced by spectrally dependent losses (optical filters) in passive driven nonlinear fiber ring resonators. Starting from an Ikeda map description of the propagation equation and boundary conditions, we derive a mean field model - a generalised Lugiato-Lefever equation - which reproduces with great accuracy the predictions of the map. The effects on instability gain and comb generation of the different control parameters such as dispersion, cavity detuning, filter spectral position and bandwidth are discussed.
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