Detailed self-consistent modelling of the lateral optical fields in an N-substrate InP/InGaAsP constricted-mesa laser diode for microwave modulation applications

High optical confinement means that many modes may be guided in the lateral direction, and it is possible for many of these modes to lase. A second problem is caused by the homojunction regions formed either side of the active layer. Current spreading at high injection can cause these regions to become forward biased. This leakage current does not contribute towards light production, and causes sub-linearity of the light-current characteristic, giving rise to harmonic distortion. A self-consistent model of the static electrical and optical properties of the constricted mesa laser has been developed to examine these problems The model includes the effects of current spreading in the p-type mesa layer and allows for the possibility the several lateral optical modes may lase simultaneously