The present investigation discusses the advantage of using RE-ion-doped (Nd 3؉ , Tm 3؉ , and Er 3؉ ) TeO 2 glasses for developing fiber and planar broadband amplifiers and lasers. The spectroscopy of RE-ion-doped fibers and glasses is discussed along with the thermal properties of glass hosts. The results of emission from the 3 H 4 level in single-mode Tm 3؉doped tellurite fiber show that the emission band overlaps with Er 3؉ emission from the 4 I 13/2 level and Nd 3؉ emission from the 4 F 3/2 level in silicate and tellurite glasses, thereby enabling the development of amplifiers and lasers between 1350 and 1650 nm. Recent results using Z-scan measurements of nonlinear refractive index and absorption demonstrate that the thirdorder nonlinearity in undoped TeO 2 glasses is of the order of 2 ؋ 10 ؊15 to 3 ؋ 10 ؊15 cm 2 ⅐W ؊1 between 1300 and 1550 nm. These results are briefly discussed in view of an amplifier operation combined with ultrafast all-optical switching.

We report observation of four- and five-photon absorption in the chalcogenide glasses at the telecommunication wavelengths. The nonlinear refractive index is sufficiently large that the optical switching criterion is satisfied.

We present the study of optical limiting in iron oxide nanoparticles of diameters 31, 44, and 61 nm dispersed in toluene under exposure to nanosecond laser pulses at 532 nm. In the low fluence region smaller size nanoparticles show better optical limiting compared to larger size nanoparticles while in the high fluence region all the three samples show same limiting performance. Experimental results were compared with the well reported limiter fullerene C(60) dissolved in toluene. Iron oxide nanoparticles show better optical limiting compared to C(60) in the intermediate fluence region and comparable performance in the high fluence region. The pico-second Z-scan studies indicate that the contribution of electronic nonlinear refractive index and the two-photon absorption to the optical limiting is negligible. Our observations further indicate that the dominant mechanism for the optical limiting in iron oxide nanoparticles is nonlinear scattering.

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