Thermal profiling: locating the onset of gain saturation in semiconductor optical amplifiers

Spatially resolved thermal profiling of a semiconductor optical amplifier enables measurement of the gain and saturation characteristics without recourse to direct optical measurements. We observe the spatial onset of gain saturation, quantify both the saturated and unsaturated gain, and accurately predict the optical output power. Effects such as suboptimal operating conditions are identified. Since this method is independent of optical measurements, it is ideal for use with integrated devices.