Provided is a method of forming a monolayer of nanorods on a substrate, wherein the nanorods are at least substantially vertically aligned, the method including providing a droplet of a solution including the nanorods on a substrate, and controlling the temperature and the evaporation of the solution such that the internal region of the droplet is kept at near equilibrium status to allow formation of the monolayer of nanorods. Also provided is a monolayer of nanorods on the substrate thus obtained. Also provided is an optical arrangement and use of the optical arrangement.