Back to Table of Contents

43862-B6
Synthesis, Photoluminescence, and Laser Characteristics of Rare Earth Ions Embedded in HEMA, a Polymeric Plastic Host

Dhiraj K. Sardar, University of Texas at San Antonio

In this project, our specific goal was to synthesize and investigate the spectroscopic and laser properties of various trivalent rare earth ions in polymeric plastic host 2-hydroxyethyl methacrylate (HEMA).

The standard Judd-Ofelt model has been applied to the room temperature absorption intensities of Er³⁺(4f ¹¹) transitions in a plastic host 2-hydroxyethyl methacrylate, referred to as HEMA, to determine the three phenomenological intensity parameters: W₂, W₄, and W₆. Values are used to determine the spectroscopic quality factor for Er³⁺ in HEMA and are compared to those for Er³⁺ in crystalline hosts. The intensity parameters are subsequently used to determine the radiative decay rates and branching ratios of the Er³⁺ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds ^2S+1L_J of Er³⁺(4f¹¹) in HEMA. Using the radiative decay rates for Er³⁺(4f¹¹) transitions between the corresponding excited states and the lower-lying states, the radiative lifetimes of eight excited states are determined.

Optical absorption and emission intensities are investigated for Ho³⁺ in hydrated holmium nitrate Ho(NO₃)₃.5H₂O embedded in 2-hydroxyethyl methacrylate (HEMA). This compound will be henceforth expressed as Ho(NO₃)₃.5H₂O:HEMA. Room temperature absorption intensities of Ho³⁺(4f¹⁰) transitions in Ho(NO₃)₃.5H₂O:HEMA have been analyzed using the Judd-Ofelt (J-O) approach in order to obtain the phenomenological intensity parameters. The J-O intensity parameters are used to calculate the spontaneous emission probabilities, radiative lifetimes, and branching ratios of the Ho³⁺ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds ^2S+1L_J of Ho³⁺(4f¹⁰). The emission cross section of the important intermanifold ⁵I₇ →⁵I₈ (2.0 µm) transition has been determined. The room temperature fluorescence lifetime of this Ho³⁺ transition in Ho(NO₃)₃.5H₂O:HEMA was measured. From the radiative lifetime determined from the J-O model and measured fluorescence lifetime, the quantum efficiency of this material was determined. The comparative study of Ho³⁺(4f¹⁰) ions suggests that Ho(NO₃)₃.5H₂O:HEMA could be an excellent candidate for certain photonic applications especially in the visible-to-near infrared region of the spectrum.

In addition, optical absorption and emission intensities are investigated for Ho³⁺ in nanocrystalline Ho³⁺:Y₂O₃. Room temperature absorption intensities of Ho³⁺(4f¹⁰) transitions in synthesized Ho³⁺:Y₂O₃ nanocrystals have been analyzed using the Judd-Ofelt (J-O) approach in order to obtain the phenomenological intensity parameters. The J-O intensity parameters are used to calculate the spontaneous emission probabilities, radiative lifetimes, and branching ratios of the Ho³⁺ transitions from the upper multiplet manifolds to the corresponding lower-lying multiplet manifolds ^2S+1L_J of Ho³⁺(4f¹⁰). The emission cross section of the important intermanifold ⁵I₇ →⁵I₈ (2.0 µm) transition has been determined. The room temperature fluorescence lifetime of this transition in Ho³⁺:Y₂O₃ nanocrystals was measured. From the radiative lifetime determined from the J-O model and measured fluorescence lifetime, the quantum efficiency of this material was determined. The comparative study of Ho³⁺(4f¹⁰) ions suggests that synthesized Ho³⁺:Y₂O₃ nanocrystals could be an excellent alternative to single-crystal Ho³⁺:Y₂O₃ for certain applications especially in the near infrared region.

One paper has been accepted for publication in a refereed journal, Optical Materials, and currently is in press.

Back to top