In Situ and Self-Restorable Injection-Locking Monitor by Integrated Photodiode for FPLD WDM Transmitter

A novel in situ self-restoration scheme to track real time the injection locking of a Fabry-Perot laser diode (FPLD) is demonstrated by a built-in integrated monitor photodiode (MPD). The variation in the received photocurrent of the integrated MPD was calculated by a microcontroller unit integrated with an analog-to-digital converter, which is employed to dynamically control the temperature of the FPLD via a thermal-electrical controller for wavelength stabilization. Such a scheme can be effectively implemented with a minimum amount of redundant network resources to achieve self-restoration within 50 s with Q factor >;8.2 and side-mode suppression ratio >;35 dB at 2.5 Gbit/s. The feasibility of the proposed self-restorable locker is suitable for most wavelength-locking FPLDs within high-speed wavelength-division multiplexing networks.