Dependance of the Bit Error Rate (BER) performance on the extinction ratio in an optical fiber communication system using a Ti:LiNbO3 waveguide modulator.

We report Bit-Error-Rate (BER) measurements, as a function of the extinction ratio, for an optical fiber transmission experiment in which a Ti:LiNbO3 directional coupler was used to externally modulate a 1.3micron multilongitudinal mode laser. We derive the experimental dependence of the power penalty at the receiver versus extinction ratio from transmission performance taken through both short (50 m) single mode fiber and long (4.1 km) dispersion shifted single mode fiber at 1.5micron radiation for data rates of 180 and 417 Mb/s using Nonreturn to Zero format. We also show that a simple BER probalilistic calculation provides good agreement with our experimental data. Finally, we evaluate theoretically the system power penalties created by our amplitude modulator with an arbitrary input polarization and consider the use of polarization maintaining fiber as a means of insuring a stable input polarization.