Suppressing Chirp and Power Penalty of Channelized ASE Injection-Locked Mode-Number Tunable Weak-Resonant-Cavity FPLD Transmitter

Amplified spontaneous emission (ASE) power and injection-locked mode number dependent frequency chirp and bit error rate (BER) responses of a weak-resonant-cavity Fabry-Perot laser diode (WRC-FPLD) transmitter are characterized. Chirp analysis of upstream data from the 1.25 Gb/s directly modulated WRC-FPLD with two and three injection-locked modes after the 200-GHz AWG filtered ASE injection-locking is determined, which reveal similar peak-to-peak chirps (Delta_vP) of -0.8 and -1 GHz with corresponding negative chirp parameters (d^middotmiddotPhi/dt²) of -1.6 and -2 MHz/ps for two- and three-mode lasing WRC-FPLD, respectively. Such a negative chirp further enlarges to -6.4 and - 9 GHz after 25-km single-mode fiber (SMF-28) transmission. The BER of below 10^-9 at receiving power below -30 dBm is obtained with mode number dependent power penalty of <0.25 dB before and after 25-km SMF -28 transmission. A chirp model involved the ASE injection induced power saturation effect is derived to explain the negatively frequency chirped WRC-FPLD, which reveals a reverse trend with increasing ASE injection power due to the power-saturation induced on/off extinction ratio reduction (from 10.5 to 8.2 dB) and rising-time broadening (from 120 to 180 ps) on WRC-FPLD transmitted data shape, which effectively reduces the peak-to-peak chirp by at least 2 GHz after 25-km SMF transmission.