Dy-doped chlorides as gain media for 1.3 μm telecommunications amplifiers

We propose that Dy³⁺-doped chloride crystals be considered as candidates for amplification of the 1.3 μm signal used by the telecommunications network. While several of these types of crystals can provide gain at the specified operating wavelength of 1.31 μm, and furthermore offer adequate bandwidth, we have focused our attention on LaCl₃:Dy as an illustrative case to explore in greater depth. Spectroscopic measurements were made on un-oriented samples of this material; excited-state lifetimes and LaCl₃:Dy³⁺ Judd-Ofelt parameters are reported. Wavelength-resolved absorption and emission cross sections are presented for the 1.3 μm W&rlhar2;Z band. Pump-probe measurements (using 0.92 μm and 1.32 μm, respectively) prove that the observed gain properties of LaCl₃:Dy are consistent with those predicted on the basis of the spectroscopic cross sections. The Dy:chloride gain media appear to have fundamental optical characteristics amenable to superior 1.3 μm telecom amplifier performance, although many fabrication issues would have to be addressed to produce a practical amplifier