The infra red absorption spectrum of Tm 3+ and Ho 3+ ions in the fluoride glass was investigated. With a Ti∶sapphire laser as exciting source, the cross relaxation process of Tm 3+ ions and infra red emission spectra of Tm 3+ sensitized Ho 3+ ions were studied. The results indicate that the cross relaxation process occurs only when the concentration of Tm 3+ ions is high (about 2 wt%). As the content of Ho 3+ ions increases, 2 μm emission intensity increases too. 2 μm emission intensity reaches maximum when the exciting wavelength is 813 nm.