Optogenetics is a fast growing neuromodulation method, which can remotely manipulate the specific activities of genetically-targeted neural cells and associated biological behaviors with millisecond temporal precision through light illumination. Application of optogenetics in neuroscience studies has created an increased need for the development of light sources and the instruments for light delivery. This paper presents a micro-lens-coupled LED neural stimulator which includes a backside reflector and a frontside microlens for light collection and collimation. The device structure has been optimized using optical simulation and the optimized device is able to increase the volume of excitable tissues by 70.4%. Device prototypes have been fabricated and integrated based on an optimization of the device structure. The measurement results show that the light power increases by 99% at an effective penetration depth of 5 000 [Formula: see text] by the fabricated device under various voltages of 2.4-3.2 V.