This paper presents the designs and test results of two radiation tolerant 4 × 10 Gb/s vertical cavity surface emitting laser (VCSEL) array drivers VLAD and lpVLAD, both fabricated in a 1.2 V 65 nm CMOS technology. VLAD adopts a power efficient bandwidth-boost technology, and lpVLAD employs a novel high-efficiency output structure to achieve an ultra-low power consumption of 2.2 mW/Gb/ch with 2 mA bias current and 6 mA modulation current. Both drivers are optically tested passing 10 Gb/s eye mask with all channels active under the radiation of a total dose up to 350 Mrad(SiO2).