Microparticle Detection With Optical Microfibers

We demonstrate a method for microparticle detection with an optical microfiber (OM). When a microparticle adheres to the uniform waist region of an OM, the transmitted loss of OM will increase due to the evanescent field perturbation. The additional loss of OM, caused by the adhered microparticle with different refractive indices and diameters, has been researched and simulated based on the evanescent field theory. We experimentally demonstrate the possibility of the method with a simple setup. Dust and alumina microparticles are detected. Experimental results have shown that the diameter of dust microparticle and the number of adhered alumina microparticles, can be estimated by measuring the additional loss of the sensing OM.