Abstract: The invention relates to a frequency changing device comprising a laser having a waveguide and a nonlinear optical medium which changes the frequency of the light generated by the laser. It is provided that the waveguide of the laser at least adjacent to the exit facet of the laser runs at an angle with respect to the perpendicular to the exit facet, that the exit facet of the laser and the entrance facet of the nonlinear optical medium are arranged parallel to one another, and that the exit facet of the laser and the entrance facet of the nonlinear optical medium are oriented with respect to one another in such a way that the condition of Snell's law is met, i.e., nlaser sin(?laser)=nnonlinear optical medium sin(?nonlinear optical medium).