An Injection-Locked Weak-Resonant-Cavity Laser Diode for Beyond-Bandwidth Encoded 10-Gb/s OOK Transmission

A coherently injection-locked and beyond-bandwidth-modulated weak-resonant-cavity laser diode (WRC-FPLD) transmitter packaged by a conventional TO-56 can package for an upstream 10-Gb/s OOK transmission is demonstrated in a DWDM-PON. With specific temperature controlling, the WRC-FPLD is able to maintain its temperature during the process of injection locking. Based on the theoretical analysis of modified rate equations, the injection-locked WRC-FPLD exhibits not only a broadband gain spectrum but also a large modulation bandwidth. Successfully implementing injection locking enhances the high-frequency throughput response but inevitably impairs the throughput intensity at a low-frequency region. By properly increasing the injection-locking power, the modulation bandwidth of the injection-locked WRC-FPLD can be further improved. In addition, the extinction ratio and the signal-to-noise ratio (SNR) of the transmitted 10-Gb/s NRZ-OOK data can also be improved from 5.58 to 6.95 dB and from 5.43 to 6.18, respectively, by increasing the injection-locking power from -12 to -3 dBm, which improves the receiving power sensitivity by 1.6 dB. The optimized receiving power sensitivity at a requested bit error rate (BER) of 10^-9 is -15.4 dBm by setting the injection-locking power at -3 dBm. After a 25-km transmission, such an overbandwidth-modulated and injection-locked WRC-FPLD reveals a receiving power sensitivity of -11.6 dBm at the same BER of 10^-9.