Design and Fabrication of Disordered Macroporous Photonic Materials*

Disordered photonic materials have unique wavelength-dependent optical properties such as near-isotropic structural coloration. Most previous studies of such materials have concerned direct photonic glasses, randomly packed spheres with a higher refractive index than the matrix they are embedded in (for example, polystyrene spheres in air). Direct photonic glasses are easy to make, but they can be fragile, and they offer limited control over optical properties. Both problems are overcome in inverse photonic glasses, in which a continuous matrix surrounds randomly packed, quasi-monodisperse low-refractive-index pores. Studies of inverse photonic glasses, however, are limited by a lack of easy fabrication methods. I will discuss the use of soft-materials fabrication methods such as emulsion and colloidal templating to make inverse photonic glasses with a wide range of matrix chemistries. Our approach is informed by Monte Carlo models of light transport that predict the optical properties of photonic glasses. I will also discuss how colloid and emulsion physics can be used to tailor the degree of disorder in these systems and manipulate their optical properties.