An optical sensor includes an interaction region configured to comprise an analyte and an illumination source configured to illuminate the interaction region with an optical input signal. The optical sensor further includes an optical coupling structure configured to collect transmitted parts of the optical input signal from the interaction region and an optical neuromorphic network that is directly optically coupled to the optical coupling structure and is configured to receive and process the transmitted parts of the optical input signal in the optical domain. The invention further concerns a related method for analyzing an analyte by an optical sensor.