Counterpropagating reflection grating dark solitons in Kerr media

We investigate counterpropagating dark (black) solitons with different envelope profiles in defocusing Kerr media in the presence of a shallow reflection grating. In the quasi-Bragg-matching regime, we are able to predict the existence of a family of counterpropagating reflection dark solitons making use of their underlying connection with the counterpropagating nonlinear plane-wave pairs with intensities that coincide with the asymptotic soliton ones. In agreement, we find through modulation instability analysis that the nonlinear plane waves are stable in that very parameter region where these dark solitons exist.