Apparatus and methods for improving optical signal collection in an integrated device are described. A microdisk can be formed in an integrated device and increase collection and/or concentration of radiation incident on the microdisk and re-radiated by the microdisk. An example integrated device that can include a microdisk may be used for analyte detection and/or analysis. Such an integrated device may include a plurality of pixels, each having a reaction chamber for receiving a sample to be analyzed, an optical microdisk, and an optical sensor configured to detect optical emission from the reaction chamber. The microdisk can comprise a dielectric material having a first index of refraction that is embedded in one or more surrounding materials having one or more different refractive index values.