  Erbium-doped lithium niobate on insulator (LNOI) laser plays an important
role in the complete photonic integrated circuits (PICs). Here, we demonstrate
an integrated tunable whisper galley single mode laser (WGSML) by making use of
a pair of coupled microdisk and microring on LNOI. A 974 nm single-mode pump
light can have an excellent resonance in the designed microdisk, which is
beneficial to the whisper gallery mode (WGM) laser generation. The WGSML at
1560.40 nm with a maximum 31.4 dB side mode suppression ratio (SMSR) has been
achieved. By regulating the temperature, WGSMLs output power increased and the
central wavelength can be changed from 1560.30 nm to 1560.40 nm. What's more,
1560.60 nm and 1565.00 nm WGSMLs have been achieved by changing the coupling
gap width between microdisk and microring. We can also use the electro-optic
effect of LNOI to obtain more accurate adjustable WGSMLs in further research.
