Interaction of noncollinear femtosecond laser filaments in sapphire

The interaction of two coherent femtosecond laser pulses, propagating at a small angle with respect to each other in a sapphire crystal in the filamentation regime, has been investigated numerically and experimentally. Distributions of the fluence and free-electron density in the laser-plasma channels formed in the crystal are obtained. Additional filaments are found to form outside the plane of initial pulse propagation.