The paper reports some initial findings in the area of analysis and characterisation of fast switching lasers, specifically Sampled Grating Distributed Bragg Reflector (SG-DBR) lasers. The ability to track the phase of a laser in the moments immediately following a switching event is an important building block in the development of an efficient Optical Burst Switching (OBS) network. In this paper it is reported, for the first time, that the use of a second-order digital Phase Locked Loop (PLL) can accomplish this task quickly and accurately without the need for programming or a-priori knowledge of the switching event per se. (5 pages)