Professor Dong Chunhua of the Guo Guangcan Team of the University of Science and Technology of China and his collaborator Zou Changling loaded the mechanical oscillation caused by the light radiation pressure in the microcavity onto the pump light, and after 5km long single-mode optical fiber transmission, stimulated the mechanical oscillation in another microcavity, and realized the full-light remote synchronization of the two optical systems through the effective regulation of the optical mode and the mechanical mode. The results of the research were published in the Physical Review Letters.
(a) Schematic diagram of full light synchronization of different light systems; (b) The dynamic process of synchronizing microspheres and microdisks through 5 km of single-mode fiber; Phase diagram of two mechanical oscillators before and after synchronization (c) and after synchronization (d). Courtesy of The University of Science and Technology of China
Until now, the all-optical synchronization distance between oscillators has only been limited to the order of microns, which greatly limits the application of synchronization networks. Despite the natural advantages of a photonic system that connects a mechanical oscillator to a photon, the implementation of full-optical synchronization experiments for long-range pyro-systems remains challenging. First of all, due to the inevitable fluctuations of optical mode and mechanical mode in the microcavular preparation process and manipulation, it is difficult to achieve exactly the same optical and mechanical modes in different microcavitation systems at the same time; Secondly, during the transmission process, the amplitude of the mechanical oscillation will attenuate, which will inevitably produce optical loss, thus limiting the distance of synchronization.
The research team proposed a new physical explanation of all-optical synchronization of the optical system, combining the injection locking mechanism with the synchronization mechanism to achieve all-optical remote synchronization. Firstly, based on the thermal light effect and light elastic effect in the microcavity, the research team achieved an optical frequency shift of up to 5.5 nm and a mechanical frequency shift of 0.42 MHz, overcoming the difficulty of simultaneous alignment of optical and mechanical modes in different optical systems.
Immediately after, the team used a coherent laser beam to drive the silica microsphere cavity, and the modulated light generated was transmitted to the microlabel cavity through a 5 km long optical fiber. At the appropriate laser frequency, the sideband-induced photodynamic interaction successfully suppresses the vacuum noise, and the output power spectrum is reduced to a single peak, achieving synchronization of the two mechanical oscillators.
The research team used a probe laser of about 1625 nm to detect the mechanical vibration of the microdisk, which further confirmed the experimental results. By characterizing the output power spectrum and phase space trajectory of the two oscillators, the two microcavities can vibrate with a fixed phase relationship and the same frequency, demonstrating the ability to synchronize light information in different wavelength bands.
The long-distance all-optical synchronization technology demonstrated in the experiment lays the foundation for the construction of a complex network of synchronous optical systems, and is expected to be applied in the fields of optical communication and clock synchronization. (Source: China Science Daily Wang Min)
Related paper information:https://doi.org/10.1103/PhysRevLett.129.063605