Inadvertent and intentional subwavelength surface texture on microoptical components

We will discuss the fabrication of several diffractive optical elements (DOEs) for projects at Sandia National Laboratories, which highlight the relative importance of subwavelength surface texture in the componentsi performance. This surface texture is in addition to the larger, anisotropic DOE features that manipulate the propagating orders, and is commonly referred to as grass. Surface texture on amorphous or multi-crystalline material is readily apparent in a scanning electron micrograph and is often an unavoidable consequence of the reactive ion etch (RIE) process. Contributing factors are mask erosion, self-masking, and material non-uniformity. In this presentation, we describe and quantify the effects of-unavoidable and deliberate surface texture through several projects in progress at Sandia National Laboratories.