D. Michaelis

Stable spatial solitons in semiconductor optical amplifiers.

The existence of stable dissipative spatial solitons at low intensities in patterned electrode semiconductor optical amplifiers (SOAs) is predicted theoretically. In contrast to conventional SOAs, this system may support stable solitons because the inherent saturating losses provide subcritical bifurcations for both the plane-wave and the soliton solution.

Dissipative solitons and their critical slowing down near a supercritical bifurcation

The existence of a novel kind of soliton in dissipative systems with competing, noninstantaneous nonlinearities has been predicted and experimentally verified. These subcritically bifurcating solitons exist near a supercritical continuous wave bifurcation. We show that their peculiarities originate from different saturation behavior of nonlinear loss and gain with regard to power and energy. Branches of stable and unstable solitary waves have been identified. For the first time to our best knowledge, we have experimentally proved critical slowing down of solitons.

Bifurcations, stability, and multistability of cavity solitons in parametric downconversion

We systematically study the formation of cavity solitons in a high-finesse, doubly resonant degenerate optical parametric oscillator. Three types of cavity soliton, emanating from different plane-wave critical points, are identified. By means of amplitude equations the bifurcation dynamics of these solutions is studied and classified. We compare cavity solitons calculated from amplitude equations with the full numerical solutions near the critical points and trace their evolution numerically far from bifurcation. We found cavity soliton types previously not identified, namely, dark and oscillating solitons. These numerical studies are complemented by a linear stability analysis of cavity solitons. Various decay situations for unstable cavity solitons are discussed.

Oscillating dark cavity solitons

We show that oscillating dark solitons exist on a stable continuous plane-wave background in a cavity with a saturable defocusing nonlinearity. These oscillations can be attributed to a linear internal mode of the soliton with a complex eigenvalue emerging above a definite input field intensity. Using a simple analytical model, we find that the self-oscillations appear as a consequence of an interaction between the center of the soliton and the surrounding ring.

Incoherent switching between multistable cavity solitons in a semiconductor optical resonator.

We demonstrate numerically a two-dimensional threefold storage scheme based on different types of solitary waves in the transmitted field of a semiconductor planar resonator. Switching between among different solitary waves can be achieved by use of a weak incoherent switching beam.

Dichromatic Cavity Solitons

Abstract We report the existence of mutually locked stable bright solitons in a planar cavitywith a quadratic nonlinearity driven at the fundamental frequency. It is shown that these solitonscan be considered as residuals of a hexagon pattern in a certain domain of parameter space of theplane wave solutions. Moreover, after excitation by a short pulse these solitons persist asindividual localized high transmission states.

Multistable Spatial Solitons in SemiconductorResonators

Abstract Direct semiconductors, as e.g. AlGaAs, exhibit huge nonlinearities for photonenergies slightly below the fundamental band edge. We show that in this domain persistent brightsolitary waves can emerge in a planar resonator. Their existence could pave the way towards anhighly parallel all-optical information processing and storage scheme. The formation of solitarywaves is primarily due to saturation of a defocusing nonlinearity, diffusion and inducedabsorption. Saturation is evoked by prominent many-particle effects like screening and band fillingwhereas the induced absorption stems from the gap renormalization. It turns out that solitarywaves of different topology may exist for the same detuning, thus representing a kind ofmultistability.

Stable spatial solitons in semiconductor optical amplifiers

The existence of stable dissipative spatial solitons at low intensities in patterned electrode semiconductor optical amplifiers (SOAs) is predicted theoretically. In contrast to conventional SOAs, this system may support stable solitons because the inherent saturating losses provide subcritical bifurcations for both the plane-wave and the soliton solution.

From resting to moving localized structures due to symmetry breaking

Summary form only given. Polarization fronts in intracavity second harmonic generation (SHG) are a representative example for localized structures or cavity solitons in dissipative systems. We use this particular example to demonstrate that nonlinear structures may destabilize due to symmetry breaking where a linear internal mode passes the translational mode. As a result a resting symmetric structure may transform into a moving asymmetric one. In the mean-field limit type II intracavity SHG is observed.

On the precise measurement of the wavevector mismatch in quadratic nonlinear crystals

The exact determination of wavevector mismatch is a crucial issue for many modern nonlinear optical applications such as all-optical signal processing, beam shaping and spatial quadratic solitons. We extend an approach to measure the wavevector mismatch in quadratic nonlinear crystals towards moderate conversion efficiencies where the low pump depletion approximation is invalid. An approximate analytical formula derived for the mismatch is experimentally verified in a KTiOPO4 crystal cut for type-II phase matching.