A symbiotic pair of dark (second-harmonic) and bright (fundamental frequency) solitons sustain each other and travel locked in second-harmonic generation dominated by group-velocity difference or spatial walk-off. The conditions of existence of the soliton pair are determined, and its stability in the presence of dispersion is discussed.
© 1996 Optical Society of America
Stefano Trillo, "Bright and dark simultons in second-harmonic generation," Opt. Lett. 21, 1111-1113 (1996)