Broadband Amplification in the 2.6–2.9 μm Wavelength Range in High-Purity Er[sup.3+]-Doped Zinc-Tellurite Fibers Pumped by Diode Lasers

In recent years, great progress has been made in the technology of high-purity and ultra-dry tellurite glasses, which has enabled the creation of high-purity single-mode tellurite fibers doped with rare-earth ions. This technology has made it possible to demonstrate laser generation in the range of about 2.7 μm in erbium-doped tungsten tellurite fibers. In this paper, we present an experimental study of broadband amplification in erbium-doped zinc-tellurite fibers. Zinc-tellurite glasses containing modifying components, such as Na[sub.2]O, La[sub.2]O[sub.3], Bi[sub.2]O[sub.3], or rare-earth metal oxides, are known to have noticeably lower phonon energy than heavy metal-tellurite systems, namely, tungsten tellurite glasses, which leads to better lasing output. The on-off gain of 30- and 60-cm long zinc-tellurite fibers has been measured in a wide range of diode pump powers. It has been shown for the first time that the amplification band is essentially extended, with pump power reaching over 250 nm (2600–2850 nm) at a peak power of about 40 W for a 30-cm long fiber.