Patent ID: 7072562

Claim:
A stepped optical fiber from multicomponent glass, said stepped optical fiber having a numerical aperture ≧0.50 and comprising a core glass member and a cladding glass member, said cladding glass member completely surrounding said core glass member, wherein said core glass member has a core glass composition, which comprises SiO 2 42 to 53% by weight, ZnO 16 to 38% by weight, PbO 1 to 20% by weight, Na 2 O <14% by weight, K 2 O <12% by weight, wherein a sum total of ZnO and PbO ≧30% by weight and a sum total of Na 2 O and K 2 O is ≧2% by weight; and wherein said cladding glass member has a cladding glass composition, which comprises SiO 2 60 to 72% by weight, B 2 O 3 <20% by weight, Al 2 O 3 <10% by weight, Na 2 O <18% by weight, K 2 O <15% by weight.