Fast Wavelength Switching at Tunable DFB Laser Array by Current/Temperature Cooperative Control

We proposed a new control method of the tunable distributed feedback (DFB) laser array (TLA) to realize high-speed optical switching by changing the injection current without sacrificing reliability. Previous studies of high-speed wavelength switching at DFB lasers achieved a sub-second switching time by injecting a large current to the active layer. However, a large injection current caused laser degradation that seriously reduced laser lifetime and reliability. In this paper, based on fast wavelength switching by injection current control, a new switching method was proposed that reduces an averaged injection current by increasing temperature. We successfully demonstrated 400-GHz-wide wavelength switching, which is the maximum tuning range of a single DFB laser in the TLA, with a switching time of 130 ms and reduced the injection current from 402 to 52 mA. Thus, we were able to greatly improve the reliability and increase the lifetime of the TLA by 60 times.