We present an all-fiber G-T resonator formed by cascading two fiber loop mirrors. Based on the superposition theory and the transfer function, the wave filtering and nonlinear phase feature of the all-fiber G-T resonator is studied and the related phase shift formula of the output beam is derived. The effect of the parameters on the phase characteristics are analyzed. An novel interleaver based on the all-fiber G-T resonator is designed. The theoretic model is simulated and calculated to meet the need of the flatness and the sharpness in the 50GHZ DWDM systems.
Through analyzing the nonlinear phase feature of the three-mirror G-T cavity, a novel unequal passband interleaver using a Michelson interferometer in which one mirror is replaced by an equally-spaced three-mirror G-T cavity is design by imitation. The device split an input beam with channel spacing of 50GHZ into two beams with channel spacing of 100GHZ. At -1dB, the odd channel and the even channel have unequal passband for transmission speed of 40Gb/s and 10Gb/s, respectively. The isolation is more than 30dB. All the possible reflection coefficients of the three-mirror G-T cavity with which the interleavers meet the above need of the DWDM system are searched out by optimization of the computer.