Wavelength tuning characteristics of DFB lasers having twin-guide structures modulated by injection current or electric field

The wavelength tuning and intensity modulation characteristics are presented for three types of twin-guide (TG) lasers entirely fabricated by metalorganic vapour phase epitaxy (MOVPE). A wide continuous tuning range of 5.3 nm is obtained for the tunable twin-guide (TTG) laser. The TTG lasers, however, have the drawbacks of output power reduction and spectral linewidth broadening during tuning. A new type of tunable laser, the complementary twin-active-guide (CTAG) laser, is proposed, and its tuning characteristics are presented for the first time. A wide continuous tuning range over 4 nm is obtained, although the thermal effect is more dominant than carrier effects. The CTAG structure enables suppression of the spectral linewidth broadening induced by the injected carrier recombination shot noise (IRSN) during tuning