Spectral characteristics for 1.5 µm DBR laser with frequency-tuning region

A 1.5 μm frequency-tunable distributed Bragg reflector (DBR) laser was developed. Frequency tuning was performed by injecting current into the DBR region where the refractive index was reduced to result in the Bragg frequency change. Threshold current and external quantum efficiency were 16 mA and 26 percent, respectively. The maximum continuous wavelength tuning range was 1.03 nm ( = 136 GHz). Spectral linewidth was maintained at an almost constant value when the wavelength was tuned. Large frequency modulation (FM) efficiency of 1-3 GHz/mA and flat FM response up to a few hundred MHz were obtained.