  We study the injection locking bistability of a specially engineered
two-color semiconductor Fabry-Perot laser. Oscillation in the uninjected
primary mode leads to a bistability of single mode and two-color equilibria.
With pulsed modulation of the injected power we demonstrate an all-optical
memory element based on this bistability, where the uninjected primary mode is
switched with 35 dB intensity contrast. Using experimental and theoretical
analysis, we describe the associated bifurcation structure, which is not found
in single mode systems with optical injection.
