GaInAsP/InP planar stripe lasers prepared by using sputtered SiO2 film as a Zn-diffusion mask

The dependence of lasing characteristics on stripe width in GaInAsP/InP double-heterostructure planar stripe lasers, prepared by using sputtered SiO2 film as a Zn-diffusion mask, was investigated. The lasers of 10-, 15-, and 20-μm-wide stripes operated in a fundamental-transverse mode with more than 20% differential quantum efficiencies per facet, while the 5-μm-wide stripe lasers operated in a multi-transverse-mode even just above threshold. The threshold current of 5-μm-wide stripe lasers increased greatly, and the lasing wavelengths shifted to shorter than those of stripe lasers with larger stripe widths. The 15-μm-wide stripe lasers showed good mode characteristics to operate in a fundamental-transverse mode up to the output power of 22 mW per facet and in a single longitudinal mode over a wide range of currents. The cause of this dependence of lasing characteristics on stripe width was discussed, and it was assumed that the Zn diffusion into the stripe region using a sputtered SiO2 mask is most responsible for the dependence.