Laser‐Induced In‐Fiber Fluid Dynamical Instabilities for Precise and Scalable Fabrication of Spherical Particles

Scalable fabrication of spherical particles at both the micro‐ and nanoscales is of significant importance for applications spanning optical devices, electronics, targeted drug delivery, biodevices, sensors, and cosmetics. However, current top‐down and bottom‐up fabrication methods are unable to provide the full spectrum of uniformly sized, well‐ordered, and high‐quality spheres due to their inherent restrictions. Here, a generic, scalable, and precisely controllable fabrication method is demonstrated for generating spherical particles in a full range of diameters from microscale to nanoscale. This method begins with a macroscopic composite multimaterial solid‐state preform drawn into a fiber that defines precisely the initial conditions for the process. It is then followed by CO2 laser heating to enable the transformation from a continuous fiber core into a series of homogeneous spheres via Plateau–Rayleigh capillary instability inside the fiber. This physical breakup method applies to a wide range of functional materials with different melting temperatures from 400 to 2400 K and 10 orders of difference in fiber core/cladding viscosity ratio. Furthermore, an ordered array of silicon‐based whispering‐gallery mode resonators with the Q factor as high as 7.1 × 105 is achieved, owing to the process induced ultrasmooth surface and highly crystalline nature.