Pole-zero diagram approach to the design of Michelson Gires-Tournois interferometer interleaver

A novel and simple design method based on pole-zero diagram is proposed for optical interleaver based on Michelson Gires-Tournois interferometer (MGTI) with arbitrary cascaded reflectors. Digital filter model which is equivalent to the MGTI optical interleaver is derived firstly. Then on the basis of it, the transfer functions of two output ports of the interleaver are simplified and all the design parameters of the interleaver can be obtained conveniently by the use of the mature design principle of elliptic filter and pole values. The two output spectrums obtained has the wide flat passband (and stopband) width and high isolation simultaneously. Compared with other existing design methods, the proposed method is simpler and more efficient, especially for interleavers with GTE composed of much more reflectors. Design examples of the interleaver with different cascaded G-T etalon structure are given.