Survey of optical and fluorescence traits of Tm3+-doped alkali/mixed alkali oxides constituting B2O3-BaO-ZnO-LiF glasses for 0.45 μm laser and 1.46 μm fiber amplifier

Abstract

For six 1 mol% Tm 3+ -doped B 2 O 3 -BaO-ZnO-LiF glasses containing single and mixed alkali oxides (fabricated by melt-cast approach), optical absorption, and visible and near-infrared (NIR) fluorescence features including visible luminescence decay times were explored. Optical band gaps, Urbach energy, and two-photon absorption coefficients were evaluated for all studied glasses. Judd–Ofelt (J–O) analysis from absorption spectra was performed to compute Tm 3+ : 4f–4f transitions J–O parameters Ω λ (λ = 2, 4, 6), and utilizing Ω 2 , Ω 4 and Ω 6 values radiative transition probabilities ( A R ), branching ratios ( β R ), and radiative lifetimes ( τ R ) for all Tm 3+ ion’s excited levels were assessed. For obtained intense blue emission band (454 nm) upon 358 nm excitation, various parameters considered in developing visible laser systems were calculated. Tm 3+ : Na ions having sample exhibits high A R , highest peak emission cross-section ( σ max em ) (=5.89 × 10 – 21 cm 2 ) and gain bandwidth ( σ max em × Δλ eff ) (=9.69 × 10 – 27 cm 3 ) for 1 D 2 → 3 F 4 luminescence transition in all glasses for a favorable blue lasing process. All emission decay curves of the 1 D 2 upper level showed nonexponential nature. Commission Internationale de l'éclairage (CIE) coordinates, color purity, and luminous efficiency of radiation were derived from visible fluorescence spectra, and attained CIE ( x,y ) coordinates values reflect the purplish-blue light region. Under direct optical pumping of 3 H 6 → 3 H 4 transition using 808 nm laser diode, NIR fluorescence spectra exhibit a wideband within 1.3–1.6 μm spectral range peaked at 1.46 μm ( 3 H 4 → 3 F 4 transition). NIR emissions effective bandwidth (Δλ eff ) was varied relying on different alkali oxides. Δλ eff ~ 121 nm was deduced for Tm 3+ : Li ions comprising glass with large σ max em (=1.832 × 10 – 21 cm 2 ), high ( σ max em × Δλ eff ) (=2.22 × 10 – 26 cm 3 ), and optical gain (=12.608 × 10 – 25 cm 2 s) for 3 H 4 → 3 F 4 emission transition and its gain profile wraps the entire S-optical communication band range for efficient broadband amplification purpose in wavelength-division multiplexing systems.

Topics & Concepts