Dispersion Compensators Based on Overlaped Linearly Chirped Fiber Gratings for DWDM Systems

By introducing a convergent lens in the phase mask setup and by tilting appropriately the fiber from the phase mask, a linearly chirped fiber grating with an appropriate chirp can be obtained conveniently. Using this method, two groups of fiber gratings, each of them is composed of 8 overlaped linearly chirped fiber gratings but with different center reflection wavelength separations (～0.8 nm and ～1.6 nm, respectively) are fabricated. Experimental results show that, the compensators based on the two groups of fiber gratings can be used to compensate for the dispersion of 8×2.5 Gb/s transmission over 100 km of standard single-mode fiber for multiple channels in optical time-division multiplexing (OTDM) and densed wavelength division multiplexing (DWDM).