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In this paper we describe empirical models for predicting the performance of high power lasers, semiconductor optical amplifiers, and superluminescent diodes. The utility of the models is verified by comparing predicted results to actual performance of devices. Based on the model, three important parameters are identified for improving the performance of high power devices. These parameters include reducing the thermal resistance, reducing the series resistance, and reducing the vertical carrier leakage. A method is described to measure the thermal resistance. We further describe experiments done to reduce the series resistance of devices to achieve a value of less than 0.5 Ω for a 1 mm long ridge device. Finally the effect of carrier stopper layers is described to reduce vertical leakage of carriers.

Broad-area laser diodes with different linewidth enhancement factors (α-factors) of 2 and 4 have been fabricated on 1.55 µm multi-quantum well structures. Far-field measurements show that the filamentation of the laser diodes is closely related to the α-factor. The full width at half maximum (FWHM) of the far-fields and the filamentation were reduced in the laser diodes with smaller α-factors. As the injection current increased, the FWHM of the far-fields also increased regardless of the value of the α-factor. This phenomenon is explained by the reduction of the filament spacing as the injection current increased. A qualitative explanation of filamentation mechanisms is given by introducing the notion of sub-aperture.

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