Optimum designs for InGaAsP/InP (λ = 1.3μm) planoconvex waveguide lasers under lasing conditions

Lasing characteristics for 1.3 μm InGaAsP/InP planoconvex waveguide (PCW) lasers were investigated both theoretically and experimentally. Fundamental lateral transverse-mode stability, light-output/ current characteristics, including threshold current and external differential quantum efficiency, and fundamental- mode intensity profiles were investigated up to a high injection-current level by using PCW lasers with individually varying structural design parameters. The experimental results were in good agreement with calculations, which were carried out taking into account carrier outdiffusion along the junction plane and spatial hole burning and their effects on the waveguiding. It was found that a narrow groove width (narrow channel), a relatively large built-in effective refractive index difference and a narrow injection current region width are the main PCW structural design conditions responsible for the high-quality lasing characteristics. The experimental results revealed that high-quality 1.3 μm InGaAsP/InP narrow-channel PCW lasers with 2.5 μm groove width show stable fundamental lateral transverse mode operation up to three times the threshold current, at which 25 m W output power from a facet is attained under CW operation.