AbstractThe 0.98‐μm InGaAs strained quantum well (QW) lasers have been fabricated. In these lasers, improvement in laser performances such as low threshold characteristic and applicability as a pumping source of Er‐doped fiber optical amplifiers are expected. The measured transparency current density and differential gain coefficient of the strained QW lasers show that they have a higher potential for low‐threshold current operation than conventional lattice‐matched GaAs QW lasers. A threshold current of 3.3 mA has been achieved in a ridge waveguide structure with high‐reflective facet coatings. A maximum output power of 85 mW and an external differential quantum efficiency of 62 percent have also been obtained by anti‐reflective and high‐reflective