From the multi-longitudinal-mode rate equations of semiconductor laser diode

based on the assumption that the spectrum as a function of wavelength is of Gauss’s distribution shape

a simple circuit model for mulit-longitudinal-mode lasers is presented

This model is very suitable for the computer-aided analysis of OEIC.It can be introduced into the existing simulator and can be used to develop new simulator.By using this model

the DC

AC and transient characteristics of a TBH-LD are studied.The simulating results agree well with the reports.The dependence of threshold and mode spectra on the cavity length is also given.