Figure 2

Fractional power overlap with the fundamental mode of the waveguide for light transmitted across a cylindrical (a) and a rectangular (b) through-hole in an optical fibre as a function of hole length. The hole is orientated perpendicular to the fibre axis, with the insets displaying the considered geometry. In panel (a) the distance of closest approach between the input and output surfaces is 30 μm. In both cases the fibre parameters used match Thorlabs 780 HP fibre, and the optical wavelength is 852 nm.