In this paper, a 2 µm broadband emission under 796 nm laser diode excitation in low phonon energy GeO_2-Ga_2O_3-BaO glass system is co-doped with 0.7Tm_2O_3/(0.07-0.7)Ho_2O_3 (mol%). The widest emission band (where the Tm^3+ → Ho^3+ energy transfer efficiency is 63%) was obtained for 0.7Tm_2O_3/0.15Ho_2O_3 co-doped glass from which a double-clad optical fiber was realized and investigated. Optimization of Tm^3+/Ho^3+ concentration enabled the acquisition of broadband amplified spontaneous emission (ASE) in double-clad optical fiber with a full width at half maximum (FWHM): 377 nm and 662 nm for 3 dB and 10 dB bandwidth, respectively. ASE spectrum is a result of the superposition of (Tm^3+: ^3H_4 →Η^3F_4) 1.45 µm, (Tm^3+: ^3F_4 → ^3H_6) 1.8 µm and (Ho^3+:^5I_7 → ^5I_8) 2 µm emission bands. Hence, highly rare-earth co-doped germanate glass is characterized by a remarkably broader ASE spectrum than silica and tellurite fibers showed promising lasing properties for their further application in tunable and dual wavelength lasers.