Recently, we proposed a three‐terminal laser structure for fast gain‐switching application using carrier heating, where hot electrons with well‐defined and variable energy are injected into an active region via resonant tunneling. A picosecond pulse generation from this device has now been analyzed, including associated transport phenomena and structure design. By means of numerical modeling we demonstrate that a resonant‐tunneling injection hot electron laser is capable of generating well‐shaped optical pulses switched by varying the injected electron energy. ©1995 American Institute of Physics.