Optical stack, optical device and optical construction

An optical device for sensing a presence of an analyte, the optical device comprising:

• a sensor material emitting a second light having a second wavelength when irradiated with a first light having a different first wavelength, a first optical property of the emitted second light being sensitive to the presence of the analyte;
• and
• an optical filter disposed on the sensor material and comprising a plurality of microlayers numbering at least 10 in total, each of the microlayers having an average thickness of less than about 750 nm, wherein:
• for a first incident angle, an optical transmittance of the plurality of microlayers versus wavelength comprises at least first and second peaks with respective first and second full width at half maxima (FWHM), the first FWHM comprising the first, but not the second, wavelength, the second FWHM comprising the second, but not the first, wavelength, each of the first and second FWHMs less than about 300 nm wide;
• and
• for a different second incident angle, an optical transmittance of the plurality of microlayers versus wavelength is less than about 10% at the first wavelength and comprises at least a third peak with a corresponding third FWHM that comprises the second, but not the first, wavelength.