Monolithic Quantum Dot Mode-Locked Laser for Arbitrary Waveform Generation

In the past, passively mode-locked semiconductor laser sources, which require no synchronization by external driver circuits, were greatly preferred for their simplicity, but were plagued with large timing jitter, > 10 ps that restricted their usefulness as short pulse devices. These passive devices also had limited power output in the pulses due to mode competition above threshold and non-linear gain effects. With the introduction of the quantum dot gain media to semiconductor lasers, the ability to tailor the active region to the passively mode-locked laser cavity and thereby produce a low threshold, low noise condition, has led to superior performance and to a re-evaluation of the monolithic passively mode-locked semiconductor laser as an ultrashort pulse optical source. The challenges, however, for quantum dot mode-locked lasers are to identify fundamental limitations to the pulse width such as non-linear gain and dispersion and to make the operation more robust. In this Phase II SBIR, we will optimize key device parameters for more stable operation, higher power and wider operating range. The ultimate goal is to develop the quantum dot mode-locked laser technology to the level where it is useable for an ultrashort pulse optical source for arbitrary waveform generation.