High-performance CW 1.26-μm GaInNAsSb-SQW ridge lasers

Long wavelength GaInNAsSb-SQW lasers and GaInAsSb-SQW lasers that include a small amount of Sb were successfully grown by gas-source molecular beam epitaxy (GSMBE). We confirmed that Sb reacts in a highly strained GaInAs-GaAs system and GaInNAs-GaAs system like a surfactant, which increases the critical thickness at which the growth mode changes from two-dimensional (2-D) growth to three-dimensional (3-D) growth. The lasers were processed into ridge lasers. The GaInNAsSb lasers oscillated under continuous-wave (CW) operation at 1.258 μm at room temperature. The low CW threshold current of 12.4 mA and high characteristic temperature (T_c) of 157 K were obtained for GaInNAsSb lasers, which is the best result for GaInNAs-based narrow stripe lasers. Further, the GaInNAsSb laser oscillated under CW conditions over 100°C. On the other hand, GaInAsSb lasers oscillated under CW operation at 1.20 μm at room temperature. The low CW threshold current of 6.3 mA and high characteristic temperature (T_c) of 256 K were obtained for GaInAsSb lasers, which is also the best result for 1.2-μm-range highly strained GaInAs-based narrow stripe lasers. We can say that GaInNAsSb lasers are very promising material for realizing an access network. Further, the differential gain of GaInNAs-based SQW lasers was estimated for the first time. GaInNAsSb-SQW lasers have the extremely large differential gain of 1.06-10^-15 cm² in spite of the single-QW lasers; therefore, GaInNAsSb lasers are also suitable for high-speed lasers in the long wavelength region