This research aims to develop wireless power supply platform for an ultra-small devices. We developed a CMOS-integrated optical power receiver that can drive an InGaN blue LED, and then integrated the CMOS chip with a capacitor and the blue LED to realize a CMOS-based implantable optical neural stimulator. The largest advantage of this device is its small size. Volume and weight of the optical neural stimulator are approximately 1 mm2 and 2.3 mg.