A drill bit for drilling a subterranean formation. The drill bit includes a drill bit body, at least one cutting element disposed on the drill bit body, and an optical sensor disposed on the drill bit body and configured to generate an environmental parameter measurement while drilling the subterranean formation. The optical sensor includes a fiber bragg grating embedded in an optical fiber that passes through a first channel in the drill bit body and a second channel in the drill string to couple to a surface logging station for analyzing the environmental parameter measurement, where the environmental parameter measurement represents at least a downhole chemical composition measured by the fiber bragg grating, and an analysis result of the surface logging station is presented to a user to facilitate a drilling operation.