Optical sensing device comprising a semiconductor substrate (S) carrying a photodetector array with at least a first and a second photodetector (P1, P2) and a filter stack arranged on the substrate (S) and covering the photodetector array, the filter stack comprising - a band-pass filter (BP), a decoupling layer (DL) arranged on the band-pass filter (BP) and a lower dielectric mirror (LM) arranged on the decoupling layer (DL), wherein each of the band-pass filter (BP), the decoupling layer (DL) and the lower dielectric mirror (LM) covers the photodetector array; - a spacer stack comprising - a primary spacer layer (SP) arranged on the lower dielectric mirror (LM), comprising a first dielectric material and covering the photodetector array; and - a first spacer layer (S1) comprising the first dielectric material, a first segment of the first spacer layer (S1) being arranged on the primary spacer layer (SP) and covering the second photodetector (P2) but not the first photodetector (P1); and - an upper dielectric mirror (UM) arranged on the spacer stack, wherein - filter elements are formed by sections of the spacer stack, the lower dielectric mirror (LM) and the upper dielectric mirror (UM), including a first filter element arranged above and covering the first photodetector (P1) and having a first pass wavelength, and a second filter element arranged above and covering the second photodetector (P2) 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 (BP), and - the decoupling layer (DL) is adapted to decouple the band-pass filter (BP) from the filter elements, such that a total transmission of one of the filter elements and the band-pass filter (BP) is given by or approximately given by a product of a transmission of the band-pass filter (BP) and a transmission of the respective filter element. - a band-pass filter (BP), a decoupling layer (DL) arranged on the band-pass filter (BP) and a lower dielectric mirror (LM) arranged on the decoupling layer (DL), wherein each of the band-pass filter (BP), the decoupling layer (DL) and the lower dielectric mirror (LM) covers the photodetector array; - a spacer stack comprising - a primary spacer layer (SP) arranged on the lower dielectric mirror (LM), comprising a first dielectric material and covering the photodetector array; and - a first spacer layer (S1) comprising the first dielectric material, a first segment of the first spacer layer (S1) being arranged on the primary spacer layer (SP) and covering the second photodetector (P2) but not the first photodetector (P1); and - a primary spacer layer (SP) arranged on the lower dielectric mirror (LM), comprising a first dielectric material and covering the photodetector array; and - a first spacer layer (S1) comprising the first dielectric material, a first segment of the first spacer layer (S1) being arranged on the primary spacer layer (SP) and covering the second photodetector (P2) but not the first photodetector (P1); and - an upper dielectric mirror (UM) arranged on the spacer stack, wherein - filter elements are formed by sections of the spacer stack, the lower dielectric mirror (LM) and the upper dielectric mirror (UM), including a first filter element arranged above and covering the first photodetector (P1) and having a first pass wavelength, and a second filter element arranged above and covering the second photodetector (P2) 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 (BP), and - the decoupling layer (DL) is adapted to decouple the band-pass filter (BP) from the filter elements, such that a total transmission of one of the filter elements and the band-pass filter (BP) is given by or approximately given by a product of a transmission of the band-pass filter (BP) and a transmission of the respective filter element. <EOS>