A DBR laser employing passive-section heaters, with 10.8 nm tuning range and 1.6 MHz linewidth

Abstract
A wavelength-tunable, three-section, distributed Bragg reflector (DBR) InGaAsP/InP laser diode is described. The refractive indices of the DBR section and the phase-control section are thermally controlled by thin-film heaters embedded on these passive sections. This structure enables wide-range wavelength tuning without the spectral linewidth broadening accompanying conventional tuning by current injection into the passive sections. A tuning range of 10.8 nm and a linewidth of less than 1.6 MHz have been achieved in the 1.5- mu m wavelength region. The temperature increase in the active layer is held to within a few degrees, even when the DBR-section temperature reaches 90 degrees C.