On-chip microdisk laser on Yb³⁺-doped thin-film lithium niobate

We demonstrate an on-chip Yb³⁺-doped lithium niobate (LN) microdisk laser. The intrinsic quality factors of the fabricated Yb³⁺-doped LN microdisk resonator are measured up to 3.79 × 10⁵ at a 976 nm wavelength and 1.1 × 10⁶ at a 1514 nm wavelength. The multi-mode laser emissions are obtained in a band from 1020 to 1070 nm pumped by a 984 nm laser and with the low threshold of 103 µW, resulting in a slope efficiency of 0.53% at room temperature. Furthermore, both the second-harmonic frequency of pump light and the sum frequency of the pump light and laser emissions are generated in the on-chip Yb³⁺-doped LN microdisk, benefiting from the strong χ⁽²⁾ nonlinearity of LN. These microdisk lasers are expected to contribute to the high-density integration of a lithium niobate on insulator-based photonic chip.