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An equivalent circuit for the 1.3 μm DCPBH laser diode is presented. The modeling is based on device geometry, measurements on isolated junctions, and transistor theory. In spite of its simplicity the model is capable of simulating several measured characteristics. Among the latter are, e.g., the (small) forward bias on the central p-n of the p-n-p-n blocking structure, the possibility of parasitic thyristor breakover, saturation of the leakage to the lateral quaternary regions around laser threshold, and the strong temperature dependence of the leakage through the p-n-p-n blocking structure as dominated by n-p-n transistor action. Quantitative and simultaneous agreement is found between simulated and measured leakage current curves and their corresponding light output versus current curves at various temperatures. The mechanism and suppression of thyristor breakover in DCPBH devices is also analyzed. It is shown that breakover occurs when the sum of effective device differential current gains equals unity. The equivalent circuit description can be used to determine this breakover point.