Calculated iso-intensity surfaces of the foci of the femtosecond excitation beam
(red) and the continuous-wave depletion beam (green) with an oblique-view electron
micrograph of a woodpile photonic crystal with 52 layers and a rod spacing of a =
350 nm made by STED-DLW. For details, see Fischer and
Wegener, Opt. Mater. Express 1, 614 (2011). .