Cascaded strongly gain-coupled (SGC) DFB lasers with 15-nm continuous-wavelength tuning

More than 15 nm of continuous wavelength tuning range has been obtained by means of temperature tuning and current setting in three-section grating-cascaded strongly gain-coupled distributed-feedback lasers. Within the entire wavelength tuning range, a sidemode-suppression ratio beyond 50 dB, a linewidth of less than 10 MHz, and a fiber-coupled output power of more than 5 dBm were achieved.