NOVELTY - A birefringent layer comprises non-polymerizable compound(s) containing two mesogenic groups comprising non-aromatic ring(s); and a bridging group connecting the mesogenic groups, and comprising subgroup(s) from pi -conjugated linear carbyl or hydrocarbyl groups, aromatic or heteroaromatic groups and being linked to an sp3-hybridized carbon-atom or silicon-atom in a non-aromatic ring of each mesogenic group. The layer optionally comprises additional compound(s) from mesogenic, liquid crystalline and/or polymerized or crosslinked compounds.    USE - A birefringent layer for, e.g. liquid crystal medium, or polymerizable liquid crystal medium for an anisotropic polymer, for an optical, electronic or electrooptical device or a component, e.g. electrooptical display, LCD, optical film, polarizer, compensator, beam splitter, reflective film, alignment layer, color filter, holographic element, hot stamping foil, colored image, decorative or security marking, LC pigment, adhesive, non-linear optic, optical information storage device, electronic device, organic semiconductor, organic field effect transistor, integrated circuits, thin film transistor, radio frequency identification tag, organic LED, organic light emitting transistor, electroluminescent display, organic photovoltaic device, organic solar cell, organic laser diode, organic integrated circuit, lighting device, sensor device, electrode material, photoconductor, photodetector, electrophotographic recording device, capacitor, charge injection layer, Schottky diode, planarizing layer, antistatic film, conducting substrate, conducting pattern, photoconductor, electrophotographic application, electrophotographic recording, organic memory device, biosensor or biochip (claimed).    ADVANTAGE - The layer has a R450/R550 of less than 1 (where R450 is optical axis retardation at 450 nm and R550 is optical axis retardation at 550 nm).    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) liquid crystal medium comprising birefringent layer and compound(s) that are optionally mesogenic or liquid crystalline;    (2) polymerizable liquid crystal medium comprising birefringent layer and compound(s) that are polymerizable and optionally mesogenic or liquid crystalline;    (3) an anisotropic polymer obtainable by polymerizing an liquid crystal material in its liquid crystal phase in an oriented state in form of a thin film; and    (4) use of birefringent layer for an optical, electronic or electrooptical device, or a component.