Sensitivity of mass sensors enhanced by higher-order exceptional points in an optomechanical system

We propose a high-sensitivity mass sensor, which is realized by a three-mode optomechanical system composed of an optical cavity with gain, an optical cavity with loss, and a mechanical resonator with loss. When the system’s parameters satisfy certain conditions, a higher-order exceptional point (EP) is shown in the eigenfrequency spectrum. Some particles with a tiny mass deposited in the mechanical resonator can give rise to the mechanical frequency shift so that the higher-order EP splits into three points, which correspond to three eigenfrequency shifts. We can obtain the adsorbed mass by measuring one of the eigenfrequency shifts. By introducing a sensitivity enhancement factor, we demonstrate that an optomechanical system with a higher decay rate can be used to implement a mass sensor with higher sensitivity. Our scheme provides important theoretical guidance for further optimization and improvement of optomechanical mass sensors.