This work investigates the concept and design of optical-duobinary vertical-cavity-surface-emitting-laser transmitters. Duobinary modulation exhibits significant advantages compared to conventional non-return-to-zero modulation.We present a novel concept: an optical duobinary transmitter. The usually problematic low bandwidth of the laser is exploited to directly generate the duobinary signal in the optical domain. For proper encoding the frequency response of the laser and the driver circuit have to match the frequency response of a duobinary encoder. Our encoderless concept does not need multilevel driver circuits or equalizers to achieve the desired high data rates. A suitable transmitter integrated circuit was designed in an advanced SiGe bipolar CMOS technology. Optical measurements show good transmission performance and efficiency at 60 GBit/s. The achieved data rate is triple the bandwidth of the laser, which is remarkable compared to the state of the art.