$C$ - and $L$ -Band External Cavity Wavelength Tunable Lasers Utilizing a Wideband SOA With Coupled Quantum Well Active Layer

We have developed a wideband semiconductor optical amplifier as a gain chip for a $C$ - and $L$ -band external cavity tunable laser. We introduced a coupled quantum well structure to obtain gain spectrum covering both bands. Low threshold current deviation, over 13-dBm fiber coupled power, and high sidemode suppression ratio were demonstrated across a 77-nm tuning range.