Experimental analysis of internal optical losses in polarization-insensitive semiconductor optical amplifiers

We experimentally investigated the internal optical loss of a polarization-insensitive multiple quantum well semiconductor optical amplifier (SOA) over a wide injection current range. The precise fitting of noise figure spectra using gain spectra and transparent wavelengths enabled a direct estimation of internal optical loss inside gain bandwidth. The internal optical loss of the SOA exhibited large dependencies on injection current and the optical confinement factor of the active layer. A large difference in optical losses between polarization modes and operating wavelengths of the SOA indicates a strong influence of intervalence band absorption. (C) 2010 American Institute of Physics. [doi:10.1063/1.3531956]