Summary form only given. In this paper, we report a new laser transmitter device that utilizes a simple, low-amplitude voltage dither signal to realize a high stimulated Brillouin scattering (SBS) threshold with low residual amplitude modulation (AM). This method relies on an intracavity phase modulator to dither the lasing wavelength, thereby broadening the optical spectrum with high uniformity. We demonstrate an SBS threshold of 25.0 dBm by applying a 100 kHz, 95 mV/sub pp/ triangle wave to the on-chip phase modulator. The resultant residual AM is only 1.2%. In addition, this laser transmitter may be tuned between four wavelength-division multiplexing (WDM) channels and permits data encoding without an external amplitude modulator.