Low-threshold and narrow-linewidth 1.5 μm compressive-strained multiquantum-well distributed-feedback lasers

1.5 μm compressive-strained multiquantum-well distributed-feedback lasers have been fabricated and characterised. 5.5 mA threshold current, 1 MHz mW linewidth-power product, and 600 kHz minimum linewidth were measured on 500 μm long devices. Measured threshold current as low as 2.2 mA was also obtained on 150 μm long devices. Both low threshold and narrow linewidth are attributed to the reduced transparency current and linewidth enhancement factor due to the effect of strain.