40 GHz Mode-Locked SOA Fiber Ring Laser with 20 nm Tuning Range

High repetition rate, picosecond laser sources are key elements for WDM/OTDM transmission, switching and photonic network systems. Active mode-locking is one of the main techniques for the generation of transform limited, high repetition rate, short pulse trains. It is particularly appropriate for applications that require precise timing synchronization between the optical and electrical signals such as digital all-optical logic [1]. The majority of tunable, actively mode-locked laser sources demonstrated so far at 1.5 m have used erbium doped fiber for gain with lithium niobate modulators to mode-lock and nonlinear compression techniques for pulse shortening [2]. These sources have demonstrated impressive performance but they are relatively complex requiring special attention to ensure stability against environmental perturbations due to their long and polarization dependent cavities. Monolithic laser diodes have also been shown to mode-lock at high repetition rates over broad tuning ranges [3] and they have been used for short pulse generation with injection mode-locking [4]. These however are research devices and they are not widely available.