Abstract: A retardation film of the present invention comprises a stretched film of a polymer film containing a norbornene-based resin, wherein the stretched film satisfies the following equation (1) and the equation (2); 100 nm?(nx?ny)·d?350 nm,??(1) 0.1?(nx?nz)/(nx?ny)?0.9,??(2) where the refractive indices in the slow axis direction, the fast axis direction and the thickness direction of the film are nx, ny and nz, respectively, d(nm) is thickness of the film, and the slow axis direction is a direction that the refractive index in film plane is maximum. The retardation film is hard to cause a shift or an unevenness of a retardation value due to a stress.

Abstract: The present invention provides photonic devices utilized in optical telecommunications. The photonic devices include photosensitive bulk glass bodies which contain Bragg gratings, particularly with the ultraviolet photosensitive bulk glass bodies directing optical telecommunications wavelength range bands. Preferably the ultraviolet photosensitive bulk glass bodies are batch meltable alkali boro-alumino-silicate bulk glass bodies. One embodiment of the invention relates to an optical element including a transparent photosensitive bulk glass having formed therein a non-waveguiding Bragg grating; and a optical element optical surface for manipulating light. Desirably, the photosensitive bulk glass has a 250 nm absorption less than 10 dB/cm.