Abstract: Disclosed is an optical fiber probe for an optical treatment including a core, to which incident light is guided, a cladding disposed to surround the core, a side surface divergence part connected to the core and configured to diverge the incident light guided to the core to a side surface of a cylindrical column, a diffusion layer disposed to surround the side surface divergence part, a distal end divergence part connected to the side surface divergence part, having a cylindrical shape, and configured to diverge the incident light guided to the side surface divergence part to the outside, and a coating layer disposed to surround the cladding and the diffusion layer and configured to seal the cladding and the diffusion layer, wherein the refractive index of the cladding is lower than the refractive index of the core, the refractive index of the diffusion layer is higher than the refractive index of the core, and the refractive index of the coating layer is higher than the refractive indices of the cladding an

Abstract: Disclosed is an optical fiber probe for an optical treatment including a core, to which incident light is guided, a cladding disposed to surround the core, a side surface divergence part connected to the core and configured to diverge the incident light guided to the core to a side surface of a cylindrical column, a diffusion layer disposed to surround the side surface divergence part, a distal end divergence part connected to the side surface divergence part, having a cylindrical shape, and configured to diverge the incident light guided to the side surface divergence part to the outside, and a coating layer disposed to surround the cladding and the diffusion layer and configured to seal the cladding and the diffusion layer, wherein the refractive index of the cladding is lower than the refractive index of the core, the refractive index of the diffusion layer is higher than the refractive index of the core, and the refractive index of the coating layer is higher than the refractive indices of the cladding an

Abstract: This ultra-low-loss optical fiber comprises a core having a higher relative refractive index difference than silica and a cladding having a lower relative refractive index difference than silica. The relative refractive index difference of the core with respect to the refractive index of silica is 0.0030 to 0.0055, for example, and the relative refractive index difference of the cladding with respect to the refractive index of silica is ?0.0020 to ?0.0003. The ultra-low-loss optical fiber has the loss characteristic of simultaneously having optical losses of at most 0.324 dB/km at a wavelength of 1310 nm, at most 0.320 dB/km at a wavelength of 1383 nm, at most 0.184 dB/km at a wavelength of 1550 nm, and at most 0.20 dB/km at a wavelength of 1625 nm. The ultra-low-loss optical fiber is supercooled when the surface temperature of the optical fiber has a temperature range in a glass transition section during drawing.

Abstract: This ultra-low-loss optical fiber comprises a core having a higher relative refractive index difference than silica and a cladding having a lower relative refractive index difference than silica. The relative refractive index difference of the core with respect to the refractive index of silica is 0.0030 to 0.0055, for example, and the relative refractive index difference of the cladding with respect to the refractive index of silica is ?0.0020 to ?0.0003. The ultra-low-loss optical fiber has the loss characteristic of simultaneously having optical losses of at most 0.324 dB/km at a wavelength of 1310 nm, at most 0.320 dB/km at a wavelength of 1383 nm, at most 0.184 dB/km at a wavelength of 1550 nm, and at most 0.20 dB/km at a wavelength of 1625 nm. The ultra-low-loss optical fiber is supercooled when the surface temperature of the optical fiber has a temperature range in a glass transition section during drawing.