외부변조 방식의 광송신기 제작 2.5Gbit/s 신호의 150km 광섬유 전송

Fabrication of an externally modulated optical transmitter and transmission of 2.5Gbit/s signal over a 150 km long nondispersion-shifted fiber)

An optical transmitter was designed and implemented using a commercially available LiNbO$_{3}$ Mach-Zehnder modulator and the power amplifiers. We have adopted a new method to stabilize the bias voltage of the modulator using the second order harmonic component of the dithering signal. This technique has been applied successfully to the 2.5 Gbit/s external modulator for more than 6 hours without bit error rate degradaton. We demonstrated a repeaterless transmission of a 2.5 Gbit/s signal over 150 km nondispersion-shifted fiber using the transmitter. The receiver sensitivity was -34.5 dBm at 10$_{-10}$ bit error rate. No appreciable BER degradation due to fiber dispersion were observed after transmission.