The fabrication of circular cross-section waveguide in two dimensions with a dynamical slit

A waveguide with a circular transverse profile can be obtained by using a slit beam shaping method. Applications about optical circuit chips in glass require a circular cross-section waveguide in two dimensions. Here we reported to realize a fabrication of circular cross-section waveguide in two dimensions by rotating the slit corresponding to the tangent line of the arc of the waveguide. The dependence of cross-section on width of the slit was investigated in experiment. The difference of slit width between geometrical optics prediction and experimental result was explained by considering the focal shift in xy directions due to diffraction effects.