Patent ID: 7577318

Claim:
A wavelength conversion layer with a matrix layer comprising embedded rare-earth-ion-doped micro crystallites or rare-earth-ion-doped amorphous particles, wherein said rare-earth-ion-doped micro crystallites or rare-earth-ion-doped amorphous particles are doped with at least one of the lanthanides, wherein said rare-earth-ion-doped micro crystallites or doped amorphous particles have a mean diameter d 50 of 10 nm to 500 μm, and wherein the matrix layer is transparent, whereby the refractive indices of said rare-earth-ion-doped micro crystallites or said rare-earth-ion-doped amorphous particles match the refractive indices of the matrix layer with a Δn≧0 and ≦0.1 for at least one wavelength in the range of 400 nm to 1200 nm.