A continuous variable modulation frequency optical single sideband (OSSB) can be generated by a Sagnac interferometer and a continuous variable differential group delay (DGD) element of photonic crystal fibers (PCFs). Furthermore, the OSSB signals with different modulation frequencies can be generated simultaneously.
Two kinds of electronic compensation of polarization mode dispersion (PMD) are demonstrated in this paper, including
transversal filter(TF) and feed forward equalizer(FFE) + decision feedback equalization(DFE). Compared with the
normalized least-mean-square (NLMS), the least-mean-square (LMS) is the best algorithm to control the equalizers. The
tap weights are adapted using the LMS algorithm until they reach stationary values. Then we focus on the structure of
FFE+DFE and find out the relationship of the number of taps and BER with different structures in the same conditions.
From the comparison, the work of 4-tap FFE+2-tap DFE is more effective, which has the most commercial value.
The basic properties including physical properties and absorption spectrum were measured firstly. Then the chromatic dispersion of air-guiding photonic band-gap fibers (PBGF) was measured with phase-shift method and pulse delay method, from experimental results we can see that their test results are accordant. The differential group delay (DGD) of the PBGF was also measured with a method of Sagnac interferometer. We found that the DGD is in direct proportion to its chromatic dispersion.