Rujiang Li, Pengfei Li, Lu Li

We design and optimize a waveguide structure consisted of three segments of PT-symmetric coupler. It can amplify the difference mode with the attenuation of the sum mode, so performs an asymmetric optical amplifier. Also, the dependence of the amplification factor for the difference mode and the attenuation factor for the sum mode on the gain/loss is illustrated.

http://arxiv.org/abs/1211.4296

Optics (physics.optics)

Yuliy V. Bludov, Vladimir V. Konotop, Boris A. Malomed

We construct dark solitons in the recently introduced model of the nonlinear dual-core coupler with the mutually balanced gain and loss applied to the two cores, which is a realization of parity-time symmetry in nonlinear optics. The main issue is stability of the dark solitons. The modulational stability of the CW (continuous-wave) background, which supports the dark solitons, is studied analytically, and the full stability is investigated in a numerical form, via computation of eigenvalues for modes of small perturbations. Stability regions are thus identified in the parameter space of the system, and verified in direct simulations. Collisions between stable dark solitons are briefly considered too.

http://arxiv.org/abs/1211.3746

Optics (physics.optics); Pattern Formation and Solitons (nlin.PS)