Optomechanical generation of a microwave frequency comb and its injection locking. (IMAGE)
Caption
Optomechanical generation of a microwave frequency comb and its injection locking. a Schematic of optomechanical injection locking with an optical microscope image of the niobium superconducting optomechanical device. A planar, spiral coil and a vacuum-gap capacitor form a lumped-element microwave resonator. The upper plate of the capacitor can freely vibrate, supporting a drum-like mechanical mode with frequency Ωm. A blue-detuned pump (blue) and an injection (orange) tone drive the device, leading to the emission of an injection-locked frequency comb (sky blue). A blue-detuned pump tone generates a noisy frequency comb with a spacing of ~ Ωm/2π. The injection tone can be introduced near any comb’s peak other than the pump tone frequency. The inset shows a close-up view of the mechanical resonator. The white scale bar is 25 μm. b The evolution of the frequency comb for different pump powers. The upper plot shows microwave spectra above (dark blue) and below (sky blue) the comb threshold power around 22.8 dBm. The right plot shows the total emitted power as a function of the pump power (red circles). c The averaged spectrum of a comb peak near fc for free-running (dark blue) and injection-locked (sky blue) combs. The total measurement time is approximately 6 min.
Credit
Microsystems & Nanoengineering
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