Modeling endface output patterns of optical micro/nanofibers

Abstract

Endface output patterns of micro/nanofibers (MNFs) are simulated using a Three-Dimension Finite-Difference Time-Domain (3D-FDTD) method. The intensity distribution and beam widths of near- or farfield output patterns of freestanding silica and tellurite MNFs with flat, angled, spherical and tapered endfaces in air and/or water are obtained. It shows that, for a subwavelength-diameter MNF, highly confined output beam can be obtained in the near field, and the beam width can be tuned by the ratio of fiber diameter and light wavelength with a minimum width smaller than the wavelength. Meanwhile, MNFs with shaped endfaces behave differently from standard fibers in reflection, redirection and focus of light beam at the endfaces. These results may offer valuable references for practical evaluation and application of terminated MNFs with wavelength- or subwavelength-scale endfaces.

Direct injection in organic SU8 nanowires and nanotubes for waveguiding properties investigation

“…7 FDTD simulation has already proved accuracy to study optical sub-wavelength propagation in nanostructures. 8,9 As determined by figure 1b,c in section 2, geometrical parameters of SU8 nanowires are set as an external diameter of 240 nm for SU8 nanowires and nanotubes, and an inner diameter of 120 nm for nanotubes. The model contains an Oy-polarised laser source at 675 nm (FWHM = 12nm) launched inside nanowires and nanotubes with refractive index of n SU8 = 1.56.…”

Optical microfiber passive components

“…In OMs, the beam output pattern is strongly dependent on OM endface geometry , but generally light can only be confined to the diffraction limit, approximated by: where ω 0 is the minimum achievable spot size, λ the wavelength of the propagating light and n the refractive index of the medium where light is focused. To overcome the diffraction limit, metal‐coated tips widely used for scanning near‐field microscopy (SNOM) have been suggested but the resulting confinement efficiency was extremely small and typically in the region of 10 −7 –10 −5 .…”

Longitudinal Lorentz force on a subwavelength-diameter optical fiber

“…When light arrives at the free end face of a SD fiber, it will encounter scattering, i.e., reflection and diffraction, due to the abrupt interface. Unlike the bulk material, the situation in SD fibers shows significantly different properties [20,21], especially due to the tight confinement accompanied by a large fractional evanescent wave propagating outside the fiber. As schematically shown in Fig.…”