Application of aerogels in optical devices

Abstract

Integrated optical devices can provide sophisticated, innovative solutions for handling light in a number of scientific and technological applications ranging from detection and chemical and biological analysis, through imaging to activation of photochemical reactions. Aerogels – with their unusually low refractive index, spectrally tunable optical transparency, possibility of doping the bulk material with chemically active atoms, molecules, and nanoparticles, and relatively low production cost – represent an attractive platform for fabricating integrated photonic circuits. This chapter provides a comprehensive review of the literature on the use of aerogels for a wide range of optical applications. First, we present an overview of the material properties of aerogels that are essential for their optical applications, concentrating, in particular, on the use of aerogels for controlled light guiding. Subsequently, we discuss possible techniques for fabricating channel waveguides in aerogel monoliths and describe in detail methods for making the channel surfaces hydrophobic. We summarize the studies in the literature on the characterization of light propagation in liquid-filled channels formed within aerogel monoliths, as well as on the quantification of light-guiding characteristics of aerogel-based waveguides. We then describe the current and possible future applications of aerogel-based optofluidic waveguides and briefly address the subject of using aerogels for fabricating lightweight optical reflectors. We conclude by a perspective on the emerging directions in the development of aerogel-based optical and photonic components and devices.