  We study the tunneling current between two counterpropagating edge modes
described by chiral Luttinger liquids when the tunneling takes place along an
extended region. We compute this current perturbatively by using a tunnel
Hamiltonian. Our results apply to the case of a pair of different
two-dimensional electron gases in the fractional quantum Hall regime separated
by a barrier, e. g. electron tunneling. We also discuss the case of strong
interactions between the edges, leading to nonuniversal exponents even in the
case of integer quantum Hall edges. In addition to the expected nonlinearities
due to the Luttinger properties of the edges, there are additional interference
patterns due to the finite length of the barrier.
