Burst-Tolerant Tuning of Reflection-Type Transversal Filter Laser With Single Active Region

We developed a tunable laser based on a reflection-type transversal filter (RTF). The RTF laser is tuned by the electro-optic effect and exhibits low-power, high-speed, and narrow-linewidth switching operation in 35-nm bandwidth. While our previously developed RTF laser has multiple active regions (ACTs) that share the laser bandwidth, the newly designed one has a single ACT. Since the slow wavelength switching among ACTs is eliminated, we achieved high-speed eight-channel switching that covers >30-nm bandwidth for switching intervals differing by a factor of 1,000 (12.5 $\mu \text{s}$ and 12.5 ms), which indicates the laser is burst tolerant. Furthermore, practical wavelength switching for 128-Gbps coherent signals was successfully demonstrated.