Phononic Frequency Comb Generation via 1:1 Mode Coupling in MoS<sub>2</sub> 2D Nanoelectromechanical Resonators
Jaesung Lee, Steven W. Shaw, Philip X.‐L. Feng
Abstract
We report on the experimental demonstration of phononic frequency comb (PFC) generation in atomically thin molybdenum disulfide (MoS <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) resonant nanoelectro-mechanical systems (NEMS) vibrating near ~50 MHz in the very high frequency (VHF) band. PFC patterns are generated by tuning two close-by resonances with a gate voltage (V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> ), and driving them at an anticrossing point, where the two modes are coupled through 1:1 internal resonance. The PFC characteristics are tunable by varying RF driving voltage (V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">drv</inf> ) and V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> . We find a threshold of PFC generation at V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">drv</inf> = 550mV and Vg = -6.4V, with relatively wide comb teeth spacing around 2.44 to 2.65MHz. At V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> = -7V, the comb teeth spacing is reduced to 0.63MHz, exhibiting strong tunability of PFC.