External electrical and optical effects in the operation of monolithic mode-locked laser diodes and the potential of nanostructure technologies in reducing these effects

The effects of the electrical parasitics and external optical reflections on the dynamic regimes and spectral properties of Fabry-Perot and Distributed Bragg Reflector monolithic mode-locked laser diodes are investigated numerically. Reduction of the range of stable mode-locking by the screening of the applied electric field by photocarriers accumulated due to the finite absorber circuit response time is investigated. External optical feedback above a certain critical value is shown to affect the laser dynamic drastically, potentially resulting in a wide range of dynamic regimes depending on the external reflector strength and position and in most cases severely degrading the laser performance, in agreement with experimental findings. The potential of some methods of reducing unwanted external electrical and optical effects, including the use of nanostructures such as deep-etched reflectors and Quantum Dot active media, is discussed.