Laser-induced　cross-linking　in　polymeric　semiconductors　was　utilized　to　achieve　micro-　and　nano-structuring　in　thin　films.　Single-　and　two-photon　cross-linking　processes　led　to　the　reduction　in　both　the　refractive　index　and　thickness　of　the　polymer　films.　The　resultant　photonic　structures　combine　the　features　of　both　relief-　and　phase-gratings.　Selective　cross-linking　in　polymer　blend　films　based　on　different　optical　response　of　different　molecular　phases　enabled　solidification　of　the　phase-separation　scheme,　providing　a　stable　template　for　further　photonic　structuring.　Dielectric　and　metallic　structures　are　demonstrated　for　the　fabrication　methods　using　cross-linking　in　polymer　films.　Selective　cross-linking　enables　direct　patterning　into　polymer　films　without　introducing　additional　fabrication　procedures　or　additional　materials.　The　diffraction　processes　of　the　emission　of　the　patterned　polymeric　semiconductors　may　provide　enhanced　output　coupling　for　light-emitting　diodes　or　distributed　feedback　for　lasers.