  Inverted nonlinear photonic crystals are the crystals featuring competition
between linear and nonlinear lattices, with minima of the linear potential
coinciding with maxima of the nonlinear pseudopotential, and vice versa.
Traditional inverted nonlinear photonic crystals only have two channels, and
can be attained experimentally by means of Rhodamine B (RhB, a dye featuring
saturable absorption) doped into the SU-8 polymer. In this paper, a new type of
inverted nonlinear photonic crystal is constructed by juxtaposing three kinds
of channels into a period. These three channels are a purely linear channel, a
saturable self-focusing nonlinear channel, and a saturable self-defocusing
nonlinear channel. This optical device is assumed to be fabricated by means of
SU-8 polymer material periodically doped with two types of active dyes. The
nonlinear propagation of a light field inside this device (passing along the
channel) can be described by a nonlinear Schrodinger equation. Stable
multi-peak fundamental and dipole solitons are found in the first gap of the
system. These solitons sufficiently exhibit some interesting digital
properties, which may have potential in optical communications.
