Optical sensing device comprising a semiconductor substrate carrying a photodetector array with at least a first and a second photodetector (P1, P2) and a filter stack arranged on the substrate and covering the photodetector array, the filter stack comprising - a band-pass filter, a decoupling layer arranged on the band-pass filter and a lower dielectric mirror arranged on the decoupling layer, wherein each of the band-pass filter, the decoupling layer and the lower dielectric mirror covers the photodetector array; - a spacer stack comprising - a primary spacer layer arranged on the lower dielectric mirror, comprising a first dielectric material and covering the photodetector array; and - a first spacer layer comprising the first dielectric material, a first segment of the first spacer layer being arranged on the primary spacer layer and covering the second photodetector but not the first photodetector; and - an upper dielectric mirror arranged on the spacer stack, wherein - filter elements are formed by sections of the spacer stack, the lower dielectric mirror and the upper dielectric mirror, including a first filter element arranged above and covering the first photodetector and having a first pass wavelength, and a second filter element arranged above and covering the second photodetector and having a second pass wavelength, - the first pass wavelength and the second pass wavelength lie within a pass-band of the band-pass filter, and - the decoupling layer is adapted to decouple the band-pass filter from the filter elements, such that a total transmission of one of the filter elements and the band-pass filter is given by or approximately given by a product of a transmission of the band-pass filter and a transmission of the respective filter element. - a band-pass filter, a decoupling layer arranged on the band-pass filter and a lower dielectric mirror arranged on the decoupling layer, wherein each of the band-pass filter, the decoupling layer and the lower dielectric mirror covers the photodetector array; - a spacer stack comprising - a primary spacer layer arranged on the lower dielectric mirror, comprising a first dielectric material and covering the photodetector array; and - a first spacer layer comprising the first dielectric material, a first segment of the first spacer layer being arranged on the primary spacer layer and covering the second photodetector but not the first photodetector; and - a primary spacer layer arranged on the lower dielectric mirror, comprising a first dielectric material and covering the photodetector array; and - a first spacer layer comprising the first dielectric material, a first segment of the first spacer layer being arranged on the primary spacer layer and covering the second photodetector but not the first photodetector; and - an upper dielectric mirror arranged on the spacer stack, wherein - filter elements are formed by sections of the spacer stack, the lower dielectric mirror and the upper dielectric mirror, including a first filter element arranged above and covering the first photodetector and having a first pass wavelength, and a second filter element arranged above and covering the second photodetector and having a second pass wavelength, - the first pass wavelength and the second pass wavelength lie within a pass-band of the band-pass filter, and - the decoupling layer is adapted to decouple the band-pass filter from the filter elements, such that a total transmission of one of the filter elements and the band-pass filter is given by or approximately given by a product of a transmission of the band-pass filter and a transmission of the respective filter element.