Fig. 5: Phonon occupancy and effective quantum cooperativity.
From: Two-dimensional optomechanical crystal cavity with high quantum cooperativity
a Plot of the measured occupancy 〈n〉 in the acoustic mode at ωm/2π = 10.02 GHz versus laser pump power in units of intra-cavity photons, nc, and optical power coupled into coupling waveguide, Pin. Filled blue circles are measured data. b Plot of quantum cooperativity Ceff versus nc and Pin. The Ceff data points (filled blue squares) are inferred using Eq. (1) from the measured 〈n〉 in a along with the fit to the measured np and γp from Fig. 4. In both a and b, the solid curves are theoretical plots calculated using the power-law fits of γp and np considering optical heating from nc alone (β = 0, red solid line curve) and including direct heating from Pin with β = 15 μW−1 (blue solid curve). c Estimated back-action cooled phonon occupancy 〈n〉 for a quasi-2D OMC device with the same properties as measured in a save for a modified Q-factor and no waveguide heating (β = 0). White solid curves delineate contours of constant quantum cooperativity Ceff. In a, b, quasi-2D OMC cavity measurements are for the same device as in Figs. 3c and 4.
