Fig. 1. Schematic diagrams of the working principle of an optical amplifier. (a) The amplification process of light; (b) (c) simplified energy level diagrams of erbium ions pumped at 980 nm and 1480 nm

Fig. 2. Simulation result analysis. (a) The particle number density of erbium ions at different energy levels corresponding to different waveguide lengths; (b) gain performance with different waveguide structure

Fig. 3. Preparation process and chip. (a) The process of preparing waveguides using the negative resist technique; (b) photograph of the Er∶LN waveguide amplifier chip

Fig. 4. Loss characterization. (a) Waveguide loss of undoped LN micro-ring at 1500-1630 nm; (b) the waveguide loss characterization of the Er∶LNOI waveguide at 1550 nm; (c) loss characterization of wide waveguide; (d) experimental and simulated results of the absorption coefficients

Fig. 5. Characterization of internal net gain. (a) Experimental setup; (b) (c) single-wavelength signal amplification of EDWA with 1.4 μm-width at 4.16 cm and 8 μm-width at 10 cm

Fig. 6. Gain performance simulation of 8 μm-width EDWA at different doping concentrations