This paper describes the design, fabrication and experiment results of a 4×8-Gbps Vertical-Cavity Surface-Emitting Laser (VCSEL) array driver ASIC with the adjustable active-shunt peaking technique and the novel balanced output structure under the Silicon-on-Sapphire (SOS) process, and a custom array optical transmitter module, featuring a compact size of 10mm×15mm×5.3mm. Both the array driver ASIC and the module have been fully tested after integration as a complete parallel transmitter. Optical eye diagram of each channel passes the eye mask at 8Gbps/ch with adjacent channel working simultaneously with a power consumption of 150mW/ch. The optical transmission of Bit-Error Rate (BER) less than 10E-12 is achieved at an aggregated data rate of 4×8-Gbps.