This paper proposed an optomechanical crystal cavity with non-suspended structure using As₂S₃ material. The principle of mode confinement in the non-suspended cavity is analyzed, and two different types of optical and acoustic defect modes are calculated through appropriate design of the cavity structure. An optomechanical coupling rate of 82.3 kHz is obtained in the proposed cavity, and the designed acoustic frequency is 3.44 GHz. The acoustic mode coupling between two non-suspended optomechanical crystal cavities is also demonstrated, showing that the proposed cavity structure has great potential for realizing further optomechanical applications in multi-cavity systems. This work has been published online by Photonics Research（Photonics Research, 2021, 9(5):893）. The first author and corresponding author of this paper are Ph. D candidate Renduo Qi and Prof. Wei Zhang, respectively.

Photonics Research（PR）is sponsored by Shanghai Institute of Optics and Fine Mechanics (SIOM), CAS, China. It is a joint publishing effort of the OSA and Chinese Laser Press, focusing on fundamental and applied research progress in optics and photonics. PR is at Q1 in JCR, and at top level (physics/optics) in CAS journal classification.