Apodization of a Grating Filter by Concatenation of Bragg Gratings with Different Ridge Patterns

We present the apodization of surface-corrugated Bragg gratings by a concatenation of dual modulation gratings that consist of two grating ridges and teeth placed asymmetrically within one period of the grating. With a feasibility study we have determined the range of possible grating patterns and hence coupling coefficients. The concatenated gratings are optimized by an evolutionary algorithm within this experimentally determined parameter space. The
demonstrated simulated grating has an intrachannel crosstalk of better than -30 dB within a bandwidth of 0.4 nm and an interchannel crosstalk of better than -20 dB outside a bandwidth of 0.8 nm.