Erbium nanoparticles (NPs) doped zinc borotellurite glasses have been prepared by conventional melt-quenching technique with the chemical composition (where ). The structural properties of the prepared glasses were determined via X-ray diffraction (XRD) analysis and FTIR analysis. It was confirmed that the prepared glasses are amorphous. The bonding parameters of the glasses were analyzed by using FTIR analysis and were confirmed to be ionic in nature. The refractive index increases as the content of erbium NPs increases. The optical absorption spectra revealed that fundamental absorption edge shifts to longer wavelength as the content of erbium NPs increases. The value of band gap had been calculated and shown to be decreased with an increase content of erbium NPs. The Urbach energy was shown to be linearly increased with an increase content of erbium NPs oxides. 1. Introduction Rare-earth doped materials have made the largest interest to develop the photonic system for various applications with regard to their advance optical properties. Erbium oxide is one of the most potential candidates among the lanthanide group in the pursuit of photonic materials research. Erbium consists of trivalent electron which is known to be advantaged to fiber amplifier applications. Nowadays, special attention is paid to explore the optical behavior of the Er3+ ions due to its emission at 1.53？μm, which is ideal for applications in the field of optical data transmission . The choice of a suitable host matrix is important to obtain the excellent optical properties. Tellurite oxide is known to be the best candidate among the heavy metal materials because of its unique optical and electrical properties. The compatibility and solubility of tellurite based glass to the other oxide glasses are the most excellent among the heavy metals. Recently, tellurite based glass has been used in several photonic devices such as precursors for infrared fibers and windows. Formation of pure tellurite oxide glass does not occur without contributions from external element. Borate oxide is known as the best choice to stabilize the glass formation due to its good rare earth ion solubility and hardness. The borate matrix possesses well defined gathering of BO3 triangles and BO4 tetrahedra to form stable borate groups such as diborate, triborate, and tetraborate . Contributions of zinc oxide in the glass formation reduce the melting point and increases the glass forming ability. It has been reported that  the effect of zinc oxide decreases the optical energy gap and increase the
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