High Frequency GaAs Nano-Optomechanical Disk Resonator
This paper introduces a GaAs nano-optomechanical disk resonator characterized by a high frequency optomechanical coupling, a distinctive feature achieved by confining optical and mechanical energy within a sub-micron scale interaction volume. The authors report an extraordinarily high optomechanical coupling rate exceeding 100 GHz/nm, significantly higher than typical values found in visible and microwave ranges, which are 10 MHz/nm and 10 kHz/nm, respectively. This heightened coupling rate is facilitated by the use of whispering gallery modes (WGM) in GaAs, leveraging its high refractive index for efficient storage and interaction of light at nano-scale dimensions.
In their experimental setup, vibrational optical noise spectra were obtained with mechanical resonances spanning from 100 MHz to 1 GHz. The disk resonators showed motional noise sensitivity approaching the quantum limit at room temperature and pressure, with optical measurement sensitivity reaching 10-17 m/√Hz. The paper employs optical evanescent fiber coupling to probe individual disks, allowing precise observation and analysis of mechanical modes. Mechanical Q factors observed were notably high, with one mechanical resonance at 858.9 MHz showing a Q factor of 862.
Importantly, the paper discusses the disk’s capability for integration in array geometries and potential interfacing with quantum dots, setting a robust groundwork for applications in quantum mechanics and high-speed sensing systems. The semiconductor nature of GaAs makes it viable for layering diverse quantum computing elements which enhance optomechanical functions. GaAs disks further hold potential for interfacing with photonic or piezoelectric mediums through quantum engineering and doping, paving the path for innovative explorations at the intersection of III-V nanophotonics and optomechanics.
The authors employed finite element methods and perturbative solutions of Maxwell’s equations for determining the optomechanical coupling, indicative of the extensive numerical modeling supporting their findings. The mechanical mode identification was correlated via SEM inspections, emphasizing an accurate methodological approach to determine resonance dispersion in varied disk sizes, and aligning these computational results with empirical data collected from broadband optical spectroscopy.
The implications of this research point toward advancements in quantum displacement sensing, with anticipated further studies on mechanical dissipation under vacuum conditions. Future theoretical developments may delve into crystalline GaAs properties, potentially surpassing limitations encountered in amorphous materials. These insights anticipate the possible integration of GaAs resonators into scalable platforms for quantum experimentations and intricate optical systems.
In conclusion, the paper provides a thorough exploration of optomechanical phenomena in GaAs nano-scale resonators, demonstrating high-frequency capabilities and sensitivity requisite for emerging quantum applications. The combination of advanced fabrication techniques and theoretical modeling showcased lays groundwork for further innovations in the field, encouraging subsequent investigations into low-temperature and vacuum conditions to fully harness the potential of these systems in quantum science and technology.