Luminescence emission and excitation spectra of bismuth-doped silica optical fibers free of other dopants have been obtained to construct an emission-excitation map in a wide wavelength range of $400–1600\mathrm{nm}$ . The main low-lying energy levels of the bismuth active centers in such fibers have been determined. For the first time (to our knowledge), optical gain and lasing have been obtained in such fibers. A gain of $8\mathrm{dB}$ has been achieved with a pump power of $340\mathrm{mW}$ , and a cw fiber laser emitting at $1460\mathrm{nm}$ with an output power of $40\mathrm{mW}$ and an efficiency of $\approx 3\%$ has been created.