Variants of a method for manufacturing a microlens of any desired shape at the extremity of a lead waveguide are provided. A lens element having a non-uniform radial etchability profile is provided at the extremity of the lead waveguide. Preferably, the etchability profile is determined by a non-uniform radial distribution of dopants in the lens element. A spacer may optionally be placed between the waveguide and the lens element. The lens element is then brought down to an appropriate length and etched to its final shape which is mainly determined by the dopant distribution. An optical coupling assembly having a non-uniform radial distribution of dopants therein is also provided.