Patent ID: 8208775

Claim:
A method of fabricating a silica-based single core optical fiber for fluorescent imaging, the method comprising: producing a silica core preform soot, doped by germanium and chlorine, by using SiCl 4 and GeCl 4 as starting materials; heating and transparent-vitrifying the preform soot in a He gas atmosphere in a sintering furnace with at least one selected from the group consisting of a SiF 4 gas, a SF 6 gas, and an fluorine series gas, thereby producing a glass rod doped with F to a specified quantity; forming a silica cladding layer on an outer periphery of the glass rod with an outside vapor phase deposition method, thereby forming an optical fiber preform; and drawing the optical fiber preform, thereby forming an optical fiber having a predetermined fiber diameter and a predetermined core diameter, wherein in the core, a Ge concentration is not less than 15 wt %, a fluorine concentration is 0.05 wt % to 2 wt %, and a chlorine concentration is 0.1 wt % to 0.3 wt %, and wherein: the optical fiber transmits excitation light, having a wavelength of 400 nm to 650 nm, incident on a first end of the optical fiber, to illuminate an object by emitting the excitation light from a second end of the optical fiber, and the optical fiber transmits light from the object, including fluorescence, incident on the second end of the optical fiber, to be emitted from the first end of the optical fiber, a relative refractive index difference between the cladding layer and the core is not less than 3%, and a ratio of an outer diameter of the cladding layer of the optical fiber to an outer diameter of the core of the optical fiber is 1.02 to 3.0.