P. Venkateswara Rao

Spectroscopic studies of Dy3 + ion doped tellurite glasses for solid state lasers and white LEDs

Rare earth ion Dy3+-doped tellurite glasses were synthesised in the system of (75-x)TeO2-15Sb2O3-10WO3-xDy2O3 (TSWD glasses). XRD and FTIR characterizations were used to find the crystalline and structural properties. The intensities of the electronic transitions and the ligand environment around the Dy3+ ion were determined using the Judd-Ofelt (J-O) theory on the absorption spectra of the glasses. The measured luminescence spectra exhibit intense emissions at 574 and 484nm along with less intense emissions around 662 and 751nm. Various radiative properties of the 4F9/2 excited level of Dy3+ ion were calculated for the glasses. Decay profiles were measured to find the life times and quantum efficiencies. Yellow to blue intensity ratio (Y/B), CIE chromaticity coordinates and correlated color temperature (CCT) values are calculated using the emission spectra to evaluate the emitted light. The obtained results suggest the utility of the glasses for potential yellow laser and white LEDs applications.

Influence of molybdenum oxide on structural, optical and physical properties of oxychloride glasses for nonlinear optical devices

Abstract The unconventional Heavy Metal Oxide Glasses (HMOG) are characterized by a low phonon energy, large infrared range transmission, high refractive index and nonlinear optical properties. Ternary glasses have been synthesized and studied in the Sb 2 O 3 – MoO 3 -ZnCl 2 system. Further, the glass formation compositional limits are reported and some glass samples with the formula: (90-x)Sb 2 O 3 -xMoO 3 –10 ZnCl 2 (10 ≤ x ≤ 50, mole%) were elaborated. Thermal properties have been measured and indicating that the glass transition temperature decreases with increasing proportions of molybdenum oxide. The evolution of density, microhardness and elastic modulus has been studied as functions of parameter x and Raman spectra measurements have been shown the partial conversion of MoO 6 octahedral units into MoO 4 tetrahedral.

Structural and Luminescence Properties of Tellurite Glasses for Laser Applications

In this chapter we will discuss in detail about structural and luminescence properties of heavy metal oxide-based TeO2 glasses incorporated by rare-earth ions. The glasses were developed by conventional melt quenching method, and the structural analysis was done by XRD, FTIR, and Raman. The XRD patterns confirm the amorphous nature of the samples, and the FTIR characterization showed the formation of more non-bridging oxygen atoms in the glass network with the inclusion of rare-earth ions. Spectroscopic characterizations such as optical absorption, photo luminescence, and decay profile measurements were performed on the glasses. The Judd-Ofelt theory has been employed on optical absorption spectra to evaluate the Judd-Ofelt (J-O) intensity parameters Ωλ (λ = 2, 4, 6). The measured J-O intensity parameters were used to determine the emission transition probability (AR), stimulated emission cross section (σ(λp)), branching ratios (βR), and radiative lifetimes (τR) for various emission transitions from the excited levels of rare-earth ions in the host glass network. The obtained results showed the use of the glasses for potential applications in the field of laser technology.