| Abstract | We demonstrate gallium phosphide (GaP) microdisk optical cavities with intrinsic quality factors < 2.8 × 10⁵ and mode volumes <10(λ/n)³, and study their nonlinear and optomechanical properties. For optical intensities up to 8.0 × 10⁴intracavity photons, we observe optical loss in the microcavity to decrease with increasing intensity, indicating that saturable absorption sites are present in the GaP material, and that two-photon absorption is not significant. We observe optomechanical coupling between optical modes of the microdisk around 1.5 μm and several mechanical resonances, and measure an optical spring effect consistent with a theoretically predicted optomechanical coupling rate g₀/2π∼30 kHz for the fundamental mechanical radial breathing mode at 488 MHz. |
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