Arbitrary chirped grating formed by one bent waveguide through a uniform periodic grating

Arbitrary chirped gratings that are very difficult to fabricate by photoresist process or electron beam lithography can be realized by a bent waveguide through a uniform periodic grating. The approximate condition that the system is equivalent to a big chirped grating is deduced. The curve function of bent waveguide can be got by resolving an integral equation. A novel binary chirped grating that could be used as an integrated optical component having combined functions of demultiplexer and focusing lens is also described. Coupled- mode theory is used to compute the efficiency of grating