High-speed planar monolithically integrated GaAs photoreceivers have been fabricated by selective ion implantation into SI GaAs substrates. Their fabrication is fully compatible with existing GaAs LSI process schedules. A receiver upper cutoff frequency of 1.5 GHz and sensitivity of 112 V/W have been measured. The application of these devices in short-haul high-bit-rate data communication systems has been demonstrated in a 560 Mbit prototype optical data link, using packaged and fibre-coupled devices.