Fig. 1. Structure model and photonic bandgap. (a) Schematic of flexible reflective film; (b) photonic bandgap diagram for a one-dimensional photonic crystal.

Fig. 2. Structural parameter simulation. (a) Reflectance spectra of the structure without coating at different periods; (b) reflectance spectra of the structure with upper surface PMMA coating at different periods; (c) and (d) reflectance ranges for TE and TM polarization modes at different incident angles with upper surface PMMA coating.

Fig. 3. Experimental principle and device diagram. (a) The principle of vacuum thermal evaporation and solution spin coating; (b) the obtained flexible one-dimensional photonic crystal reflective film (inset shows a flexible reflective film being wound on a 5-mm-diameter glass rod); (c) SEM cross-sectional images of cleaved chalcogenide reflector show periodic alternation of films in the multilayers.

Fig. 4. Reflection spectra of one-dimensional photonic crystals under different conditions. (a) The reflection spectra of prepared chalcogenide multilayers with different periods and added polymer layers, namely PPSU (red), one period (blue), four periods (black), and four periods with upper surface PMMA coating (green); (b) the reflection spectra of the prepared four-period chalcogenide multilayers at different incident angles, namely 0° (black), 30° (red), 45° (blue), and 60° (green); (c) the reflection spectra of prepared chalcogenide multilayers with different period thicknesses, d is 1.94 µm (black) and 1.62 µm (red) corresponding to λ₀ of 10.1 µm and 8.5 µm.