Bistable operation in InP/InGaAsP DH lasers by optical injection is reported for the first time. An incident optical beam, generated by a conventional DH semiconductor laser, was injected into the semiconductor laser with inhomogeneous excitation. Bistability has been achieved in the relation between input intensity of the incident beam and the optical output intensity of the inhomogeneously excited laser. The bistable laser also acts as an optical limiter, i.e. the optical output completely saturates above the laser threshold level.