A light guide structure (100) has a first main surface (101) and an opposite second main surface (102) and is configured to guide light in the light guide structure via total internal reflections at the first and the second main surfaces. The light guide structure comprises an out-coupling arrangement (120) configured to couple light propagating in the light guide structure out of it through the first and/or the second main surface. The light guide structure comprises two cladding layers (1111, 1112) and a core layer (110) sandwiched between the cladding layers, the core layer comprising a core material and the cladding layers comprising cladding materials, respectively. The core material has its elasticity higher than the elasticities of the cladding materials, and its refractive index for a design wavelength substantially the same as the refractive indices of the cladding materials.