Orbital angular momentum mode fiber force sensing technology based on intensity interrogation.

Micromanipulation and biological, materials science, and medical applications often require controlling or measuring the forces exerted on small objects. Based on the high linearity and sensitivity of OAM beams in the sensing field, this article proposes for the first time to apply OAM beams to force sensing. In this paper, a fiber optic force sensing technology based on the intensity distribution change of orbital angular momentum (OAM) mode is proposed and realized. This technique detects the magnitude of the external force applied to the fiber by exciting the OAM mode with a topological charge 3, thereby tracking changes in light intensity caused by mode coupling. Applying this technique to force measurement, we have experimentally verified that when the sensor is subjected to a force in the range of 0mN to 10mN, the change in speckle light intensity at the sensor output has a good linear relationship with the force. Meanwhile, theoretical analysis and experimental results indicate that compared with previous force sensing methods, this sensing technology has a simple structure, is easy to implement, has good stability, and has practical application potential.