Synchronized Mode-Locked Semiconductor Lasers and Applications in Coherent Communications

The general features and characteristics of two different external-cavity mode-locked semiconductor lasers (MSLs) were studied. Coherent optical frequency combs and short pulses from the MSLs were used to develop a synchronized MSL system. Exploiting the synchronized MSLs as a phase-locked transmitter and a local oscillator, various heterodyne and homodyne coherent detection techniques were experimentally demonstrated. The experimental results have shown that the phase-coherent optical frequency combs and short pulses from the synchronized MSLs are very promising optical sources for many future coherent photonic systems, especially for spectrally phase-encoded optical code-division multiple access (SPE-OCDMA).