The mode-controlled nonlinear process in a highly nonlinear photonic crystal fiber is studied experimentally. The central wavelength of frequency-upconverted dispersive wave and its transverse intensity profile are controlled through a selective coupling of the pump field to the higher order modes of the fiber and a polarization-sensitive phase matching process. However, due to their large effective index difference, the two orthogonal modes cant be excited simultaneously. The index difference is lowered by injecting wax into the air holes which effectively modifies the core structure. This modification degenerates the two orthogonal high-order modes. As a result, they are excited simultaneously and form a hollow beam output.