Optical phase-lock loops using semiconductor lasers

This thesis demonstrates theoretically and experimentally that it is possible to use semiconductor lasers without external cavities or other linewidth narrowing devices in Optical Phase-Lock Loops (OPLLs). A comprehensive analysis of OPLL theory is presented including the effect of loop delay time. A performance comparison is made between modified first order loops and second order loops revealing that modified first order loops are less sensitive to loop delay time. Stability conditions are set and the main loop performance parameters of phase error spectrum and variance are calculated. A cycle-slip criterion is fixed and the relationship between laser linewidth, loop bandwidth and loop delay time is discussed to guide the loop design. The optical and electrical design of an heterodyne OPLL is detailed. Experimental work is presented concerning temperature control, loop filter design, optical mixing and isolation. Double Quantum well lasers are described and characterised. Details of an heterodyne OPLL using laser diodes without external cavity or any other linewidth narrowing device are given. The loop has a measured phase error variance of 1.02rad2