Gain characteristics of polymer waveguide amplifiers based on NaYF₄:Yb³⁺, Er³⁺ nanocrystals at 0.54 μm wavelength

Gain characteristics of polymer waveguide amplifiers based on NaYF₄:Yb³⁺, Er³⁺ nanocrystals (NCs) at 0.54 μm wavelength were investigated through numerical simulations. NaYF₄:18%Yb³⁺, 10%Er³⁺ NCs were doped into SU-8 2005 polymer matrix as the core of a polymer waveguide. The absorption spectrum and photoluminescence spectrum of the NCs were recorded and analyzed. The Judd-Ofelt parameters were achieved by means of Judd-Ofelt theory: Ω₂ = 6.302 × 10^-20 cm², Ω₄ =0.69 × 10^-20 cm², Ω₆ = 7.572 × 10^-20 cm². We simulated the gain characteristics of the waveguide amplifier at 0.54 μm wavelength by combining the atomic rate equations with power propagation equations. The gain curves had the saturation effects. A maximum gain ∼4.3 dB for the 5 cm waveguide with the Er³⁺ concentration of ∼7.5 × 10²⁵ m^-3 was obtained.