Abstract: An integrated fluorescence detector for detecting fluorescent particles is described. An example integrated fluorescence detector comprises a substrate, the substrate comprising an integrated detection element for detecting fluorescence radiation from fluorescent particles upon excitation of the particles with incident excitation radiation. The integrated fluorescence detector also comprises a sensing layer adapted for accommodating fluorescent particles to be sensed. The integrated fluorescence detector further comprises a photonics crystal layer arranged in between the sensing layer and the substrate, the photonics crystal layer comprising an absorption material designed such that the photonics crystal layer is configured for diffracting incident excitation radiation into a lateral direction in which the photonics crystal layer extends for incident excitation radiation having a wavelength within at least 10 nm of the predetermined excitation wavelength.