Patent ID: 8208774

Claim:
A silica-based single core optical fiber for fluorescent imaging, comprising a core comprising a Ge concentration which is not less than 15 wt %, a fluorine concentration which is 0.05 wt % to 2 wt %, and a chlorine concentration which is 0.1 wt % to 0.3 wt %; and a cladding layer cladding the core, wherein excitation light having a wavelength of 400 to 650 nm, which is incident from a first edge, is transmitted and illuminated to an object by emitting from a second end, a light from the object including a fluorescence is incident to the second end and is transmitted and emitted from the first edge, a relative index difference of the cladding layer and the core is not less than 3%, and a ratio of an outer diameter of the cladding layer to a diameter of the core is 1.02 to 3.0.