A sample of single cladding highly Yb3+-doped silica optical fiber with high absorption and low background loss is fabricated by MCVD process with a new type of annular graphite heater furnace.Its geometric parameters and absorption spectrum are measured

analyzed and discussed

resulting in the conclusion that the key to this fabrication lies in depositing a high quality porous phosphosilicate layer（the soot layer） and that the P doing in the soot layer is helpful to the dopant solubility.Its absorption can be as high as 594 dB/m at 976 nm but its background loss is only 0.1 dB/m.