Kerr-nonlinearity-modulated dressed vortex four-wave mixing from photonic band gap

Inelastic two-wave mixing induced high-efficiency transfer of optical vortices

A scheme for high-efficiency transfer of optical vortices is proposed by an inelastic two-wave mixing (ITWM) process in an inverted-Y four-level atomic medium, which is originally prepared in a coherent superposition of two ground states. The orbital angular momentum (OAM) information in the incident vortex probe field can be transferred to the generated signal field through the ITWM process. Choosing reasonable experimentally realizable parameters, we find that the presence of the off-resonance control field can greatly improve the conversion efficiency of optical vortices, rather than in the absence of a control field. This is caused by the broken of the destructive interference between two one-photon excitation pathways. Furthermore, we also extend our model to an inelastic multi-wave mixing process and demonstrate that the transfer efficiency between multiple optical vortices strongly depends on the superposition of the ground states. Finally, we explore the composite vortex beam generated by collinear superposition of the incident vortex probe and signal fields. It is obvious that the intensity and phase profiles of the composite vortex can be effectively controlled via adjusting the intensity of the control field. Potential applications of our scheme may exist in OAM-based optical communications and optical information processing.

Intensity instability and correlation in amplified multimode wave mixing

The dynamics of optical nonlinearity in the presence of gain and feedback can be complex leading to chaos in certain regimes. Temporal, spectral, spatial, or polarization instability of optical fields can emerge from chaotic response of an optical \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\chi ^{(2)}$$\end{document}χ(2) or \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\chi ^{(3)}$$\end{document}χ(3) nonlinear medium placed between two cavity mirrors or before a single feedback mirror. The complex mode dynamics, high-order correlations, and transition to instability in these systems are not well known. We consider a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\chi ^{(3)}$$\end{document}χ(3) medium with amplified four-wave mixing process and study noise and correlation between multiple optical modes. Although individual modes show intensity instability, we observe relative intensity noise reduction close to the standard quantum noise, limited by the camera speed. We observe a relative noise reduction of more than 20 dB and fourth-order intensity correlation between four spatial modes. More than 100 distinct correlated quadruple modes can be generated using this process.

Azimuthal and radial modulation of double-four-wave mixing in a coherently driven graphene ensemble

We investigate in detail the azimuthal and radial modulation (i.e., the azimuthal order l_j and radial order p_j with j = 1, 2) of double-four-wave mixing (double-FWM) by use of two higher-order Laguerre-Gaussian (LG) beams in a Landau quantized graphene ensemble. A pair of weak probe pulses in the graphene ensemble interacts with two LG beams and thus two vortex FWM fields with the opposite vorticity are subsequently generated. In combination with numerical simulations, we reveal that (i) there appear l₁ + l₂ periods of phase jumps in the phase profiles under any conditions; (ii) p + 1 concentric rings emerge in the intensity profile and the strength is mainly concentrated on the inner ring when the two LG beams have the same radial orders (i.e., p₁ = p₂ = p); (iii) there are p raised narrow rings occurring in the phase profile in the case of p₁ = p₂ = p and l₁ ≠ l₂, and the raised narrow rings would disappear when p₁ = p₂ and l₁ = l₂; (iv) p_max + 1 concentric rings appear in the intensity profile, meanwhile, |p₁ - p₂| convex discs and p_min raised narrow rings emerge in the phase diagram in the case of p₁ ≠ p₂, here p_max = max(p₁, p₂) and p_min = min(p₁, p₂). Moreover, the two generated FWM fields have the same results, and the difference is that the phase jumps are completely opposite. These findings may have potential application in graphene-based nonlinear optical device by using LG beams with adjustable mode orders.