Physical Review A
Analytical properties of the initial-value problem for zero-area pulses
Sami A. Shakir
Abstract
The inverse scattering technique is used to show that the phase term in the Maxwell-Bloch equations should be set to zero when the slowly varying envelope approximation is assumed for self-induced transparency. A solvable model of two square pulses shifted and inverted with respect to each other is considered, and the threshold for "breather" generation for this profile is shown to correspond to an initial absolute area of $\ensuremath{\surd}2\ensuremath{\pi}$ when the separation between the two pulses is zero, and approaches $\ensuremath{\pi}$ as the separation is increased. When the two pulses are identical, only breathers are found. Upper bounds on the energy of the $0\ensuremath{\pi}$ pulses are derived, along with threshold conditions for soliton generation. For an absolute area less than $\ensuremath{\pi}$ there are no bound solutions.