Fig. 1. Schematic of the fabrication process for Er3+/Yb3+ co-doped LNOI waveguides.

Fig. 2. SEM images of the (a) cross section and (b) longitudinal section of Er3+/Yb3+ co-doped LN waveguide. Simulated electric field distribution of single mode in the LN waveguide at (c) λ=974  nm and (d) λ=1531  nm.

Fig. 3. Schematic of the experimental setup for characterization of Er3+/Yb3+ co-doped LNOI waveguide amplifiers.

Fig. 4. Optical transmission spectra of Er3+/Yb3+ co-doped LNOI microring resonators on the same chip in (a) 980 nm band and (b) 1550 nm band. The Lorentz fit (red line) shows 2.03×105 and 1.43×105 loaded quality factors near 974 and 1531 nm, respectively. (The inset shows the SEM image of a microring resonator with a radius of 100 μm used for testing in the 1550 nm band.)

Fig. 5. (a) Measured signal spectra at ∼1531.31  nm with increasing pump powers of 0, 0.21, 0.46, 2.96, and 6.20 mW. (b) Dependence of net internal gain on pump power at a fixed on-chip input signal power of ∼28  nW. (c) Net internal gain as a function of increasing signal power at a fixed pump power of ∼6.20  mW. (d) The measured internal conversion efficiency (purple dot) is used as a function of signal power. The red dashed line shows a linear trend based on small signal gain.

Fig. 6. (a) Infrared absorption spectra of Er3+/Yb3+ co-doped, Er3+ doped, and Yb3+ doped LN. (b) Infrared emission spectra of Er3+/Yb3+ co-doped, Er3+ doped, and Yb3+ doped LN under 980 nm excitation at high pump power. The inset shows the infrared emission spectra of Er3+/Yb3+ co-doped and Er3+ doped LN at lower pump power. (c) Decay curves of the Yb3+ emission at 1062 nm in Er3+/Yb3+ co-doped and Yb3+ doped LN, excited under 980 nm. (d) Decay curves of the Er3+ emission at 1531 nm in Er3+/Yb3+ co-doped and Er3+ doped LN, excited under 980 nm.