Effect of hole pile-up at heterointerface on modulation voltage in GaInAsP electroabsorption modulators

Input optical power dependence of the modulation voltage for GaInAsP electroabsorption modulators is studied. It is shown that the photogenerated hole pile-up at a heterointerface induces the increase of modulation voltage for the same extinction ratio with increasing the input optical power. The effect of the hole pile-up was greatly reduced in the new structure with the buffer layer of intermediate bandgap between the GaInAsP waveguide and InP upper clad layers.