Optical injection effects and all‐optical set‐reset operations in two‐segment strained multiquantum‐well (MQW) distributed feedback (DFB) bistable lasers were experimentally investigated. The optical bistable characteristics under detuned optical injection, of strained MQW DFB bistable lasers, show the effect of the residual Fabry–Perot side modes of the DFB structures; optimizing the input wavelength and the input power is suggested for applications. The switching properties of dynamic optical set‐reset operations with pulsed optical injection were reported, which appear to be related to the optical bistable characteristics under cw optical injection; however, the switching transients are found to be essential to full understanding of these switching properties. ©1996 American Institute of Physics.