A Study of All-fiber Different Bandwidth Interleaver Based on Linear Chirped Fiber Grating

Abstract

To improve the utilization efficiency of interleaver bandwidth in 10Gbit/s plus 40Gbit/s mixed system, an all-fiber MZI different bandwidth optical interleaver based on linear chirped fiber grating is proposed and discussed in this paper. The same two linear chirped fiber gratings are written at the output of conventional Mach-Zehnder interferometer (MZI), which constitute a reflective cascaded MZI filter. Based on its structure, the output spectrum expression is established and described by using the principle of fiber transmission, reflex theory of fiber grating and the matrix transfer function. Influences on its transmission characteristics by such factors as the coupling coefficients of the couplers, structure parameters of fiber grating and the length differences of the interferometer arms are numerically analyzed and optimized. The results of numerical simulation indicate that when the above parameters are some certain values, 50GHz input single of device is separated into channel spacing of 100GHz odd-even two output signals. Their spectrum bandwidth are 64.67GHz and 36.98GHz at 3dB, they satisfy the requirement of different transmission rates on bandwidth in 10Gbit/s plus 40Gbit/s mixed system and implements different bandwidth transmission. The device has a certain ability to resist the deviation. Compared with the ordinary cascaded MZI interleaver, the advantage of the new interleaver is that reduced numbers of coupler. It has higher bandwidth utilization that compared with the equal bandwidth interleaver, and achieves different bandwidth transmission within 100GHz.