Abstract: Systems and methods are provided for providing a passively switched light source. An integrated optical component includes a photonic material and a phase change material in direct contact with the photonic material. A light source provides light into the integrated optical component. The light interacts with the phase change material such that an index of refraction of the phase change material depends on the intensity of the light within the integrated optical component as to provide a passive change to a parameter of the integrated optical component.

Abstract: Resonant sensors and methods of detecting specific molecules with enhanced sensitivity. Optical energy is introduced into a microcavity, such as a silica toroid-shaped microcavity. The microcavity sensor has a functionalized outer surface and a sufficiently high Q value to generate an evanescent optical field with increased intensity. A molecule bound to the functionalized outer surface interacts with the external optical field, thereby heating the microcavity and generating a detectable resonant wavelength shift, which indicates a small number of molecules, even a single molecule, without the use of fluorescent or metal labels. Resonant sensors and methods can also be used to detect specific molecules, even a single molecule, within an environment. One application is detecting very small quantities or a single molecule of heavy water in ordinary water.