Novel all-electrical scheme for dynamic semiconductor laser-to-fibre coupling control

An all-electrical scheme to maintain the optimum coupling condition in semiconductor laser-to-fibre coupling is described. A small deviation (¿¿) of the optimum laser-to-fibre distance severely degrades the laser performance in terms of, for example, output power, longitudinal mode spectrum and pulse response. The scheme employs the electrical noise of the laser as a distance sensor in a control loop that maintains the optimum laser-to-fibre distance in the presence of thermal or mechanical disturbances.