Measurement of the Internal Loss Coefficient of Semiconductor Optical Amplifiers

The internal optical loss in semiconductor optical amplifiers (SOAs) is investigated experimentally and theoretically over a wide injection current range. A new measurement method is proposed without noise figure spectra. Theoretically, considering the internal loss in an SOA, a modified formula of the input-output characteristics is deduced. Based on the practically measured input-output characteristic curves, the internal loss coefficient of an SOA is measured at different injection currents. The results demonstrate that the internal loss coefficient of SOAs decreases with increasing injection current.