Assessing aging in tunable electro-absorption modulated, distributed Bragg reflector lasers

Tunable optical sources used in dense wavelength division multiplexed (DWDM) systems, such as distributed Bragg reflector (DBR) lasers, are highly susceptible to aging-induced wavelength drift. Without the stabilizing influence of gain clamping in the tuning section, the tendency for a tunable source to drift is greater than that of a fixed wavelength source, such as a distributed feedback or electroabsorption modulated laser. Aging of tuning sections can cause a free-running tunable source to wander out of an allotted channel band or, in a severe case, to mode hop. Wavelength drift in a tunable source is mitigated by closed loop feedback, but with time, aging still distorts the multi-dimensional channel map of optimized operating conditions. Assessing the potential for a tunable source to age is essential to ensuring device and system reliability. Using a novel technique, we assess aging in an electro-absorption modulated, distributed Bragg reflector (EADBR) laser using change of Bragg wavelength as a measure of increase of non-radiative recombination.