Narrow-linewidth (<200 kHz) operation of 1.5- mu m butt-jointed multiple-quantum-well distributed Bragg reflector laser

Linewidths as narrow as 200 kHz were achieved with a 1.5 mu m butt-jointed multiquantum-well (MQW) distributed Bragg reflector (DBR) laser. A low threshold current of 8 mA and a high output power of 28 mW were also realized, as well as narrow-linewidth operation. The device was fabricated by a five-step metalorganic vapor-phase epitaxy (MOVPE) process. These results were realized by introducing a high-quality MQW active layer, a long DBR region with a very small coupling coefficient, and a butt-jointed region with high coupling efficiency.>