We investigated an all-optical logic AND operation at 10 Gb/s using nonlinear transmission of electroabsorption modulator pumped with two counterpropagating data streams. The transmitted pump itself was used as the output of the optical gate to obtain high extinction ratio, and high-output peak powers. The gate has been tested using 2/sup 31/-1 long pseudorandom bit sequence. The logical output of the gate has an extinction ratio of more than 10 dB with good eye opening. Our measurements of the gate transmission window show that all-optical logic operation up to 100 Gb/s is feasible.