A device can include both a photosensing component and an optical cavity structure, with the optical cavity structure including a part that can operate as an optical cavity in response to input light, providing laterally varying output light. For example, the optical cavity can be a graded linearly varying filter (LVF) or other inhomogeneous optical cavity, and the photosensing component can have a photosensitive surface that receives its output light without it passing through another optical component, thus avoiding loss of information. The optical cavity part can include a region that can contain analyte. Presence of the analyte affects the optical cavity part's output light, and the photosensing component can respond to the output light, providing sensing results indicating the analyte's optical characteristics.