An optical element includes a light guide plate with a first major surface and with a second major surface opposite the first major surface and with side faces connecting the first and second major surfaces, wherein the light guide plate includes a matrix material transparent to ultraviolet light in which scattering centers are embedded, at least one light-emitting semiconductor device that couples ultraviolet light into the light guide plate via a side face when in operation, a first filter layer on the first major surface and a second filter layer on the second major surface, wherein the filter layers opaque to ultraviolet light and at least partially transparent to visible light, and a first photochromic layer at least on the first major surface, between the light guide panel and the first filter layer, with a transparency to visible light by ultraviolet light.