Abstract: Method for producing a modulated grating for an optimal reflection spectrum, which grating is a multiple wavelength reflector. The method includes the following steps: a) Determining wavelengths to be reflected b) Calculating a preliminary grating c) Comparing the reflection spectrum ro(f) with the characteristics of the wanted modulated grating d) Differences lead to a directional change of ro(f) e) Calculating a target function G(z) f) Changing the grating (zk) depending on the real and imaginary part of G(z) g) Repeating steps c) to f) until the grating reflects the predetermined wavelengths.