Simple tunable all-fiber delay line filter for dispersion compensation

A delay line filter with tunable group delay for residual dispersion compensation is presented. The device is suitable for channel bit rates of 40 Gb/s and consists mainly of two 3 /spl times/ 3 fiber couplers connected in series. Due to the all-fiber implementation, it has low polarization sensitivity and can be directly inserted in the transmission line. Its dispersion value can be tuned by simply changing the optical phase in one filter path. Thereby, a tuning range of /spl plusmn/50 ps/nm is realized with a very good agreement between simulation and measurement.