Method for producing photonic crystals

A process for producing three-dimensional photonic crystals, comprising the process steps of

• a) providing an inorganic photoresist which, on illumination with energy which is greater than the electronic band gap of the photoresist, exhibits a phase alteration,
• b) illuminating the photoresist with a laser beam whose energy is lower than the electronic band gap of the photoresist, but whose intensity at the focal point is so high that nonlinear effects occur there, as a result of which a phase alteration occurs in the photoresist, wherein the photoresist which consists of a binary, ternary or multinary compound which comprises an element of main group VI of the periodic table,
• c) repeatedly moving the laser beam and the photoresist relative to one another and repeating process step b),
• d) developing the illuminated photoresist in an etching solution which preferably dissolves one phase of the photoresist,
• e) removing the developed photoresist as a photonic crystal;
• wherein the non-linear effects recited in step (b) are multiphotonic processes and;
• wherein
• the etching solution comprises an organic Lewisbase.