PREDISTORTION OF ELECTROABSORPTION MODULATORS FOR ANALOG CATV SYSTEMSAT 1.55-MU-M

A predistortion circuit with adjustable amounts of third-and fifth-ord er predistortion is studied both theoretically and experimentally. The circuit is used to cancel the third- and fifth-order intermodulation distortion of a 1.55-mu m integrated electroabsorption modulator/DFB l aser, The CSO obtained is -61 dBc and the CTB is reduced 22.6 dB to -6 5 dBc, This performance is maintained after fiber amplification and pr opagation through 13 km of nondispersion shifted fiber due to the modu lator's low chirp, Dithering of the DFB laser's injection current is e mployed to increase the stimulated Brillouin scattering (SBS) threshol d to +13.4 dBm.