ernary PbO-{{{{ {Bi }_{2 } {O}_{2 } }}-{{{{ {Ga }_{2 } {O}_{3 } }} glasses doped with various rare-earths were prepared and multiphono re-laxation phenomenon associated with an intra-4f-configurational transition was investigated. Phenomeno-logical multiphnon relaxation rates of heavy metal oxide glasses in the PbO-{{{{ {Bi }_{2 } {O}_{2 } }}-{{{{ {Ga }_{2 } {O}_{3 } }} system were the lowest among oxide glasses and comparable to that of fluoride glasses. As a result fluorescent emissions in the mid-infrared and 1.3 $mu extrm{m}$ wavelengths which are quenched in oxide glasses became evident