Properties of natural diamond microlenses fabricated by plasma etching

Refractive microlenses with diameters of between a few micrometers to a few hundred micrometers have received much attention, due to their numerous applications in, for example, optical communications, optical data storage, digital displays, and laser beam shaping. Wide band-gap inorganic materials, including GaN, SiC and ZnO have proved popular for these applications in recent years due to their attractive optical and electronic properties. However, it is anticipated that these materials will be superseded for many applications by diamond. Advantageous properties including optical transparency, high thermal conductivity and high carrier mobility make natural diamond an attractive choice, but its hardness and chemical inertness provide a significant challenge for device processing. This paper demonstrates the ability to etch natural grade-IIa diamond using inductively-coupled plasma etching and discusses the properties of the finished lenses in terms of surface roughness, surface profile and focal length.