Impact of different pumping and signal schemes on amplification performance of erbium-doped Ga₂O₃ waveguides

Mode solutions simulations are employed to optimize the waveguide structure to enhance light interaction with rare-earth ions. Subsequently, an Er³⁺:Ga₂O₃ waveguide with an optimized structure is fabricated. The optical gain performance is characterized under bidirectional 980 nm pumping, using either a supercontinuum source or a single-wavelength laser as the signal. For a 0.5 cm long waveguide with a -32.4 dBm signal power and launched pump power of 59.4 mW, a net gain of 14.4 dB/cm at 1545 nm is obtained using the single-wavelength signal source. The maximum internal net gain reaches 23.2 dB/cm at a low signal power of -42 dBm, demonstrating the potential of amorphous gallium oxide thin films as a waveguide amplifier host material.