High speed directly modulated single mode lasers are becoming important optical components for short reach communication. In order to cover a transmission distance that is required for PON and inter data-center applications, the chirp managed laser (CML) is an attractive transmitter technology. This technology enables to use a directly modulated laser (DML) for longer reach systems, resulting in a smaller footprint, low fabrication cost and lower power consumption. Error free 10 Gb/s non-return-to-zero-on-off-keying (NRZ-OOK) data transmission over 20 km standard single mode fiber (SMF) is demonstrated using a heterogeneously integrated III-V-on-Si distributed feedback laser in combination with a tunable optical filter as a transmitter and a Ge-on-Si waveguide-coupled Avalanche Photodiode (APD) with an integrated transimpedance amplifier (TIA) as a receiver. For inter-datacenter applications, by increasing the bias current of the laser (improving its modulation bandwidth and output power) and using a faster silicon-contacted germanium waveguide p-in photodetector with an integrated TIA, 28 Gb/s NRZ-OOK data transmission over 20 km standard single mode fiber is demonstrated..