High-rejection/low-loss single passband filters with 50 nm stopband in depressed cladding fibre by chirped grating concatenation method

High-rejection/low-loss bandpass filters have been successfully fabricated in cladding depressed fibre by concatenating four chirped gratings achieving a 50 nm stopband with rejection ratio of 50 dB and /spl sim/1.5 nm (at 3 dB) passband with a loss /spl sim/1 dB.