| 摘要 |
<p>A method of calculating a sampling function for fabricating a N-channel grating, the method comprising the steps of forming a summation of N periodic seeding functions each describing a refractive index variation, wherein each periodic function includes a phase shift value Ζl (l=1, ...N) with respect to the other functions, and wherein at least one phase shift value is non-zero. The sampling function may be expressed as: Σ ? exp[i (K0z+θ+(2l-N-1)Δλz/2+ζl]=λQ exp[i (K0z+θ+γ)], where Q=Q(z) is the amplitude and γ=γ(z) is the phase of the sampling function, and the summation is performed over l=1,...N. The method may further include the step of determining a set of the phase shift values for which a maximum value of the sampling function amplitude is minimised.</p> |
