Efficient electro-optical tuning of an optical frequency microcomb on a monolithically integrated high-Q lithium niobate microdisk

We demonstrate efficient tuning of a monolithically integrated lithium niobate (LN) microdisk optical frequency microcomb. Utilizing the high optical quality (Q) factor (i.e., Q ∼ 7.1 × 10⁶) of the microdisk, the microcomb spans over a spectral bandwidth of ∼ 200 nm at a pump power as low as 20.4 mW. Combining the large electro-optic coefficient of LN and the optimum design of the geometry of microelectrodes, we demonstrate electro-optical tuning of the comb with a spectral range of 400 pm and a tuning efficiency of ∼ 38 pm/100 V.