Improved quantum efficiency of GaInAsP/InP top air-clad lateral current injection lasers

An internal quantum efficiency (η
_i
) of GaInAsP/InP top air-clad lateral current injection (LCI) lasers was considerably improved by covering the top surface with 50-nm thick InP cap layer. As the result, threshold current of 6.7 mA and the differential quantum efficiency of 56% were attained for five-quantum-wells (QWs) LCI laser with the cavity length of 500 μm and the stripe width of 1.5 μm.