High-Q Trampoline Resonators from Strained Crystalline InGaP for Integrated Free-Space Optomechanics

Nanomechanical resonators realized from tensile-strainedmaterialsreach ultralow mechanical dissipation in the kHz to MHz frequencyrange. Tensile-strained crystalline materials that are compatiblewith epitaxial growth of heterostructures would thereby at the sametime allow realizing monolithic free-space optomechanical devices,which benefit from stability, ultrasmall mode volumes, and scalability.In our work, we demonstrate nanomechanical string and trampoline resonatorsmade from tensile-strained InGaP, which is a crystalline materialthat is epitaxially grown on an AlGaAs heterostructure. We characterizethe mechanical properties of suspended InGaP nanostrings, such asanisotropic stress, yield strength, and intrinsic quality factor.We find that the latter degrades over time. We reach mechanical qualityfactors surpassing 10(7) at room temperature with a Q center dot f product as high as 7 x 10(11)Hz with trampoline-shaped resonators. The trampoline is patternedwith a photonic crystal to engineer its out-of-plane reflectivity,desired for efficient signal transduction of mechanical motion tolight.

Automated summary

Nanomechanical resonators made from tensile-strained materials have extremely low mechanical dissipation in the kHz to MHz frequency range. These materials also allow for the realization of monolithic free-space optomechanical devices with properties such as stability and scalability. In this study, we demonstrate nanomechanical string and trampoline resonators made from tensile-strained InGaP, and characterize their mechanical properties and performance.