Gap solitary waves with gain and two-photon absorption

We examine the properties of gap solitaires in media exhibiting two-photon absorption alone, and also in media with linear gain as well. Using an effective-particle approach, we derive expressions for the time evolution of the solitaire’s frequency detuning and velocity. We predict that gap solitaires are slowed down for a wide range of parameters, which is partly confirmed by comparison with results from numerical simulations. However, these also show that solitaires are destroyed before significant slowing can occur due to the uncontrolled growth of side wings.