When an integrated optical component is asymmetrically excited, a radiated field is generated. Most of the time, the energy carried by the radiated field is lost. However, with high-level integration structures, this field can couple back into another waveguide and then disturb the operating conditions of the whole component. An original waveguide geometry that rapidly removes this radiated field is thus proposed here. The study of a specific Y-junction shows that it is possible to reduce by a factor of at least 30 the length of the Y-junction's straight waveguide. Computer modelling was performed with the radiation spectrum method (RSM), a new beam propagation method, perfectly suited to dealing with the field coming from guided and radiation modes. It gives us a good physical understanding of the light propagation.