Soliton-comb generation in ring-shaped optical Kerr microresonators under thermal effects

Abstract

Soliton combs are nonlinear wavetrains resulting from entanglements of localized waves which may be pulse or kink solitons, forming periodic structures called soliton crystals. In this work we examine the possible generation of soliton-comb structures in an optical Kerr microresonator in the ring configuration, considering the physical context where the laser stores heat in the ring cavity leading to sizable thermo-optical effects. To proceed with the study we consider an existing model proposed for this physical context, in which the optical field contribution to time evolution of the heat in the microresonator is described by the its average power. With help of appropriate variable changes the model is formulated in terms of a set of coupled first-order nonlinear ordinary differential equations, which are solved numerically paying particular attention to the impact of thermal effects on characteristic parameters of the soliton crystal structures, and also on the profile of time evolution of the temperature in the microresonator cavity. Simulations show that for the specific model considered, thermal effects do not oppose the formation of soliton crystals in the optical Kerr microresonator undergoing thermo-optical effects. Nevertheless the induced thermal detuning is likely to cause the average amplitude of the soliton crystal to increase or decrease, depending on variations of thermal coefficients in the heat equation.