Broadband saturable absorber with cobalt-doped tellurite glasses

A robust solid-state saturable absorber was developed with cobalt-ion-doped tellurite glasses that has a broad saturable-absorption band in the near-infrared. A nonlinear optical absorber was measured by the Z-scan technique. Numerically fitting the Z-scan experimental data yields excited-state absorption cross sections at a 1064-nm laser wavelength of σ_es = 1.45 × 10^-20 and σ_es = 1.15 × 10^-20 cm² for 1.0- and 2.5-at. % Co ²⁺-doped glasses, respectively.