Luminescence in germania-silica fibers in a 1-2 μm region.

We analyze the origins of the luminescence in germania-silica fibers with high germanium concentration (about 30 mol.% GeO) in the region of 1-2 μm with a laser pump at the wavelength 532 nm. We show that such fibers demonstrate the high level of luminescence which unlikely allows the observation of photon triplets, generated in a third-order spontaneous parametric downconversion process in such fibers.