Widely tunable 1.55-μm lasers for wavelength-division multiplexed optical fiber communications

Widely tunable lasers are essential components for high-capacity wavelength-division-multiplexed (WDM) transmission and photonic switching systems. For these optical fiber communication systems, they offer several advantages to increase the capacity, the functionality, and the flexibility of WDM networks. Nevertheless, these widely tunable transmitters must satisfy several stringent requirements depending on the specific application for which they are intended. Using criteria defined to compare the performances of several widely tunable laser structures reported in the literature, we pointed out a structure which presents a good tradeoff between high performances and technological processing simplicity. We designed and realized this component, the sampled-grating distributed Bragg reflector laser. Its tuning mechanism and main characteristics are first discussed. A short review is then made to compare these results to those measured on different widely tunable structures, and to propose improvements needed for practical implementation of these lasers for WDM optical fiber communications.