light-matter momentum interaction, and they have been widely explored for optical tweezing, binding, and actuation. [6][7][8][9] Based on the optomechanical system, optical nonreciprocity and bistability have been studied theoretically and demonstrated experimentally. For optomechanically induced nonreciprocity, [10] it has been experimentally realized via micromechanical oscillators [11,12] and microcavities such as microspheres, [13,14] microtoroids, [15,16] and photonic crystal cavities. [17] The microto nano-meter scale sizes and femtogramscale effective masses of these structures lead to their significant responses to optical forces. However, the optical forceinduced mechanical responses are generally trivial for optical structures at millimeter scale or beyond, making it difficult to experimentally realize optical nonreciprocity via macroscopic optomechanical systems. For optical bistability, [18] although

A typical optomechanical system is a cavity with one movable mirror and one fixed mirror. However, this configuration has been considered incapable of integrating sensitive mechanical elements while maintaining high cavity finesse. Although the membrane-in-the-middle solution seems to be able to overcome this contradiction, it introduces additional components that will lead to unexpected insertion loss, resulting in reduced cavity quality. Here we propose a Fabry–Perot optomechanical cavity composed of an ultrathin suspended Si3N4 metasurface and a fixed Bragg grating mirror, with a measured finesse up to 1100. Transmission loss of this cavity is very low as the reflectivity of this suspended metasurface tends to unity around 1550 nm. Meanwhile, the metasurface has a millimeter-scale transverse dimension and a thickness of only 110 nm, which guarantees a sensitive mechanical response and low cavity diffraction loss. Our metasurface-based high-finesse optomechanical cavity has a compact structure, which facilitates the development of quantum and integrated optomechanical devices.

No abstract

We theoretically propose an optomechanical system based on suspended metasurface to achieve low threshold optical bistability. By integrating the silicon nitride (Si3N4) membrane with metasurface, it can achieve a near-unity reflectivity around 1550 nm, when it forms an optomechanical cavity with a high-reflectivity fixed mirror, its 2 mm 2 mm size and 100 nm thickness enable it to respond sensitively to radiation pressures on the order of 100 milliwatts.Benefit from the excellent optical and mechanical properties of the metasurface, the optomechanical system performs strong optomechanically induced nonlinearity, and exhibits optical bistability at intensity of aboot 1.5 W/cm-2.