Optically driven angular alignment of microcomponents made of in-plane birefringent polyimide film based on optical angular momentum transfer

The optically driven angular alignment of micromachined components (microlenses and microprisms) within a single-beam optical trap using a linearly-polarized laser is presented. This optically induced angular alignment around the laser beam axis results from the spin angular momentum of the laser beam produced by the birefringence of the trapped microcomponents. The microcomponents are fabricated by reactive ion etching of an in-plane birefringent polyimide film (retardation = Δnd = 0.76λ where Δn = nslow-nfast is the birefringence, d is the thickness and λ is the wavelength). The fabricated microlenses and microprisms are made to align at desired angular positions simply by changing the direction of the vibration plane of a linearly-polarized laser beam.