COUPLED SOLITONS IN WAVE-GUIDES WITH 2ND-ORDER AND 3RD-ORDER NONLINEARITIES

The analytical form of coupled temporal solitons in waveguides with se cond- and third-order nonlinearities is presented. The solutions are o btained for group-velocity dispersions of the same sign for both funda mental and second-harmonic frequencies. In particular, three types of coupled soliton are found: bright solitons, which can exist in materia ls with second- or third-order nonlinearities; semidark (twin-hole) so litons, which require materials with second-order nonlinearity; and gr ay coupled solitons existing only in materials with both nonvanishing nonlinearities. (C) 1995 Optical Society of America