Narrow spectral linewidth of MBE-grown GaInAs/AlInAs MQW lasers in 1.55 μm range

The spectral behavior of ridge-type GaInAs/AlInAs multi-quantum-well (MQW) lasers made by molecular beam epitaxy (MBE), which are capable of CW operation at room temperature, is reported. The wafers were grown by conventional metal-source MBE on Sn-doped (100) InP substrates. The n-type MQW active layer was composed of ten GaInAs wells and nine AlInAs barriers. The spectral linewidth was evaluated by a delayed self-homodyne scheme with a 3-km optical fiber. The measurements were carried out at 5°C stabilized within ±0.01°C. The minimum linewidth of 3.6 MHz was achieved at an output power of 7 mW. The effect of cavity length on the linewidth was also confirmed. At an output of 5 mW, a linewidth of about 3 MHz was obtained for a diode with a 750-μm cavity length. The results indicate that the MBE-grown wafers have good uniformity A small dynamic spectral linewidth (called chirping) is also demonstrated.