  We investigate the vacuum pp-wave and Aichelburg-Sexl-type solutions in f(R)
and the modified Gauss-Bonnet theories of gravity with both minimal and
nonminimal couplings between matter and geometry. In each case, we obtain the
necessary condition for the theory to admit the solution and examine it for
several specific models. We show that the wave profiles are the same or
proportional to the general relativistic one.
