External cavity semiconductor lasers with resonantly enhanced modulation response are shown to be suitable for efficient narrow-band data transmission in the millimeter wave range (35 GHz) at frequencies beyond the intrinsic modulation bandwidth of the diode. A small-signal rate equation model is presented to analyze the modulation response as well as the amplitude noise in such a resonant transmitter system. Analysis and measurements show that the relative intensity noise is also resonantly enhanced, but the signal-to-noise ratio is not degraded.