  We construct the AdS-plane wave solutions of generic gravity theory built on
the arbitrary powers of the Riemann tensor and its derivatives in analogy with
the pp-wave solutions. In constructing the wave solutions of the generic
theory, we show that the most general two tensor built from the Riemann tensor
and its derivatives can be written in terms of the traceless-Ricci tensor.
Quadratic gravity theory plays a major role; therefore, we revisit the wave
solutions in this theory. As examples to our general formalism, we work out the
six-dimensional conformal gravity and its nonconformal deformation as well as
the tricritical gravity, the Lanczos-Lovelock theory, and string-generated
cubic curvature theory.
