Characteristics of a tapered hollow micro-tube emitting a Bessel light beam

Abstract

We found that the tip size of a tapered hollow micro-tube can affect the properties of an emitted Bessel light beam. In addition, the incident light polarization state was also found to influence the characteristics of the emitted light beam. From a lithography viewpoint, we looked at the correlation between an emitted Bessel light beam from a subwavelength annular aperture on metallic film and from a tapered hollow micro-tube. Intensity profiles were analyzed using finitedifference time-domain (FDTD) simulations and lithography experiments were undertaken. The approaches used to couple the incident light into the hollow micro-tube and to the subwavelength annular aperture are discussed. Effects from the waveguide mode were studied. Our results showed that the tube thickness of the tapered hollow micro-tube tip is an important factor in generating the Bessel light beam wavelength. We show that lithography can be used with a through-silicon-via (TSV) process in a far-field region while maintaining a near diffraction-limit spot size. Our tapered hollow tube design is useful for applications such as optical lithography, super resolution optical detection, and fabrication of high aspect ratio structures.