Photonic micro- and nanostructures provide the opportunity to
manipulate photons within small volumes for biophotonic applications11–
15. Photonic crystals, first proposed in the 1980s, can be
useful for controlling the density of photon states by creating
a medium with artificially designed periodic structures16.
Biocompatible photonic crystals can extend the utility of these structures
to applications such as reflection-based or label-free biosensing17,18.
In the context of this work, previous reports focusing on
the mechanical properties of silk have demonstrated silk monoliths
with porous nanoscale inverse structures at scales appropriate for
photonic applications19. Here, we bring together silk and photonic
crystals and report the manufacture of robust, free-standing,