J. Eur. Opt. Society-Rapid Publ. 22, 12( 2026) 121
Figure 8. Reflectance spectra( a, d) and photonic band structures as a function of the incidence angle for TE( b, e) and TM( c, f) polarisations in the cases of the photonic models corresponding to Calliphora vicina( a – c) and Lucilia richardsi’ s( d – f) photonic structures. Green areas correspond to allowed photonic bands.
thicknesses are much larger than the incident light coherence length.
The simulated optical responses of the multilayer models generally match the experimental reflectance spectra in both peak position and angular dependence. The accordance between experimental and numerical results demonstrates the photonic origin of the visual appearances of the investigated blow flies. For C. vicina, however, the simulated reflectance peak is noticeably narrower than the experimental one. This difference could arise from imperfections in the multilayer structure, such as random variations in layer thicknesses, and from the fact that experimental measurements were averaged over a relatively large solid angle. To assess this effect, we modelled a pseudo-periodic multilayer with random thickness deviations of ± 15 nm in the high-contrast layers and ± 5 nm in the low-contrast layers, and averaged the resulting calculated spectra over incidence angles from �5 ° to + 5 °( Fig. S3). This approach produced a broader peak than the ideal model, though still narrower than the measured spectrum.