Laser Fabrication of Ship-in-a-bottle Microstructures in Sapphire

The technique of laser trapping (or laser manipulation, laser tweezers) was proposed by Ashkin more than 30 years ago [1]. This technique made the three-dimensional (3D) positioning of small objects possible using a tightly focused laser beam [2]. The fields of application of laser manipulation are diverse and include biology, physics, and micromachining, to name a few.[3,4] In addition to the control of position (momentum), the laser trapping technique can simultaneously control the rotation (angular momentum) of the object in some cases. Control of angular momentum is achieved in several ways. In one, the angular momentum of the laser beam is used [57]. A photon of a circularly-polarized laser beam has an angular momentum of π 2 h = Ω where h is the Planck’s