ANALYSIS OF GAIN AND SATURATION CHARACTERISTICS OF A SEMICONDUCTOR-LASER OPTICAL AMPLIFIER USING TRANSFER-MATRICES

The transfer matrix method (TMM) has been applied to analyze the gain and saturation characteristics of semiconductor laser optical amplifie rs. This method approximates the amplifier cavity by dividing it into M discrete subsections, and TMM has been applied to analyze the stepwi se longitudinal field distribution at each subsection along the amplif ier cavity. By incorporating also the carrier rate equations into the analysis, it has been shown that the approximation can accurately desc ribe the carrier density and longitudinal field distribution along the amplifier cavity if M is sufficiently large (i.e., the size of each s ubsection is about an order of magnitude of one wavelength of the inpu t signal). By assuming that the amplifier is biased below oscillation threshold such that the contribution of spontaneous emissions to the g ain characteristics can be neglected, we have shown that our proposed method yields a fast and efficient algorithm in analyzing the gain and saturation characteristics of laser amplifiers. We have compared the results produced by our method to those analyzed using the average pho ton density (AVPD) approximation technique, as well as to experimental results on a 1.5-mu m buried heterostructure semiconductor laser ampl ifier.