  We demonstrate thermalization and Bose-Einstein (BE) distribution of photons
in standard erbium-doped fibers (edf) in a broad spectral range up to ~200nm at
the 1550nm wavelength regime. Our measurements were done at a room temperature
~300K and 77K. It is a special demonstration of thermalization of photons in
fiber cavities and even in open fibers. They are one-dimensional (1D),
meters-long, with low finesse, high loss and small capture fraction of the
spontaneous emission. Moreover, we find in the edf cavities coexistence of
thermal equilibrium (TE) and lasing without an overall inversion. The
experimental results are supported by a theoretical analysis based on the rate
equations.
