The lens embraces a bulk-shaped lens body identified by a top surface, a bottom surface and a contour surface, and a well-shaped concavity is implemented in the inside of the lens body, aligned from the bottom surface toward the top surface. The lens body has geometry such as bullet-shape or egg-shape. A ceiling surface of concavity implemented in the lens body serves as a first lens surface, the top surface of the lens body serves as the second lens surface, and inside of the concavity serves as a storing cavity of a light source or a photodetector.