Optical connection of several remote nanooptomechanical systems
For the first time, physicists have coupled remote optomechanical nano-oscillators via an optical wave guide. This coupling allowed them to observe the locking of the oscillators on a common frequency of oscillation. These results are published in the journal Physical Review Letters. The light injected into an opto-mechanical resonator can cause spontaneous oscillations.
The mechanical pressure exerted by the light on the walls of the optical resonator which confines it deforms the latter and induces acoustic vibrations, which act in return on the intensity of the light. Beyond a threshold, the resonator becomes mechanical oscillator. After a few years of existence in laboratories, these systems are now well developed.
The challenge today is to realize collective architectures consisting of multiple oscillators connected by optical links to develop optical / mechanical simulators and topological structures for light and vibration. Up to now, the coupling had been carried out only between two oscillators very close to each other, by means of near- field effects.
The nanoresonators as well as the optical guides connecting them were made of gallium arsenide by etching a wafer consisting of a hetero structure of gallium arsenide and aluminum gallium arsenide. The resonators are discs of the order of 3 micrometers in diameter and 320 nanometers thick, resting on rods 1.7-micrometer high and 300 nanometers in diameter.
About 25 micrometers separate the disks, while waveguides connect two or three of these resonators. The infrared light injected tangentially into these discs is confined to their periphery in an optical gallery mode. This optical mode is mechanically coupled to guide acoustic breathing by which the disc expands and contracts radically to a frequency in the range of one gigahertz.
One of the major difficulties in the realization of this system is to produce sets of resonators whose optical resonances are at the same frequency, to inject light laser monochromatic in all resonators simultaneously. For this purpose, Post-fabrication tuning of finely reduces the dimensions of discs that are too large thanks to a photo-assisted etching in fluid medium.
After making and adjusted this device, researcher has injected infrared light in the operating guide wave and analyzing the radio frequency spectrum of this light exiting the device. Above the threshold, when the resonators become oscillators, a fine mechanical peak by oscillator appears in this spectrum. By progressively increasing the intensity of the light connecting the oscillators, these distinct peaks are replaced abruptly by a single peak. It corresponds to a common frequency of oscillation for all the oscillators: c ‘ Is the phenomenon of locking in frequency.http://www.thetechnologylounge.com/optical-connection-of-several-remote-nanooptomechanical-systems/High Tech Devicesnanooptomechanical systems