1.5-μm strained-layer MQW-DFB lasers with high relaxation-oscillation frequency and low-chirp characteristics

1.5-μm wavelength strained-layer multiple-quantum-well (SL-MQW) distributed-feedback (DFB) lasers for optical video distribution systems, including optical-fiber amplifiers, are studied with respect to the relaxation-oscillation frequency and wavelength chirp characteristics. Several types of lasers are examined as parameters of amount of strain, optical confinement, and detuning. It is confirmed that the introduction of negative detuning has an obvious effect on the increase in relaxation-oscillation frequency f_r and the reduction in chirp ΔF. The SL-MQW DFB lasers with low optical confinement and negative detuning show extremely low FM response ΔF/ΔI of less than 60 MHz/mA as well as high f_r over 10 GHz for the first time. Additionally, low-chirp value ΔF of 180 MHz with modulation depth of 10% is realized at relatively low bias current (I_h=I_th+30 mA)