Femtogram dispersive L3-nanobeam optomechanical cavities: design and experimental comparison

Abstract

We present the design and experimental comparison of femtogram L3-nanobeam photonic crystal cavities for optomechanical studies. Two symmetric nanobeams are created by placing three air slots in a silicon photonic crystal slab where three holes are removed. The nanobeams' mechanical frequencies are higher than 600 MHz with ultrasmall effective modal masses at approximately 20 femtograms. The optical quality factor (Q) is optimized up to 53,000. The optical and mechanical modes are dispersively coupled with a vacuum optomechanical coupling rate g(0)/2π exceeding 200 kHz. The anchor-loss-limited mechanical Q of the differential beam mode is evaluated to be greater than 10,000 for structures with ideally symmetric beams. The influence of variations on the air slot width and position is also investigated. The devices can be used as ultrasensitive sensors of mass, force, and displacement.

Electromagnetically induced transparency in optical microcavities

“…optical force, which includes two major categories: radiation pressure force (or scattering force) and optical gradient force (or dipole force). Various experimental systems existing such interactions are proposed and investigated, including FP cavities [94,95], whispering-gallery microcavities [96][97][98][99], microring cavities [100], photonic crystal cavities [101][102][103][104], membranes [105][106][107][108], nanostrings [109], nanorods [110][111][112], hybrid plasmonic structures [113], optically levitated particles [114][115][116][117][118][119][120], cold atoms [121][122][123], and superconducting circuits [124]. The phenomenon of OMIT was theoretically predicted by Agarwal and Huang [125] and further analyzed for optical pulse storage [126].…”

Ultraviolet optomechanical crystal cavities with ultrasmall modal mass and high optomechanical coupling rate

“…The design in this work has a shorter optical resonant wavelength 393.03 nm, a higher mechanical frequency 14.97 GHz, and a smaller modal mass 22.83 fg. The modal mass is comparable with the designed values of the world’s smallest optomechanical systems based on the concept of NEMS-in-cavity5152. The large optomechanical coupling rate 1.26 MHz facilitates obtaining a large cooperativity for strong photon–phonon interaction5.…”

“…With a novel design and optimization strategy based on tuning the OMC mirrors, we can improve the modal confinement as well as the spatial overlap between the optical and mechanical modes, which enables the simultaneous achievement of high Q factors, high mechanical frequency, ultrasmall modal mass, and high optomechanical coupling rate. For the optimized OMC nanobeam cavity, the modal mass 22.83 fg is comparable with the designed values of the world’s smallest optomechanical systems5152, yet a high optomechanical coupling rate greater than 1.00 MHz is also achieved. The f m · Q m product is in the 10 14  Hz regime.…”

Dynamical and quantum effects of collective dissipation in optomechanical systems

“…A detailed analysis of the CB/SB crossover in optomechanical arrays has not yet been reported and most of the works generally assume independent dissipation affecting optical and mechanical units. On the other hand, collective mechanical dissipation has been recently reported in some experimental platforms [44,45], such as OMs composed by two coupled nanobeams in a photonic crystal platform (environment). Photonic crystals are indeed also a known tool to suppress mechanical dissipation [46,47].…”