LAUSR

Real-time measurement and control of optical nanofiber diameters are of particular importance in many applications. Here, we propose and demonstrate a novel and simple method to control the nanofiber diameters in real time, which is based on monitoring the intensity of light scattered from the evanescent field using a femtowatt photodetector. Our experimental results show that the ultra-high precision is within 3 nm and accuracy is within 10 nm in the control of diameters ranging from 400 nm to 750 nm. Our method is also universal and can be extended to optical fibers with other wavelengths.