Broad gain spectra of single and multiple InGaAsN quantum well systems

The optical gain of single and multiple quantum well systems fabricated from InGaAsN/GaAs was investigated. We performed a numerical analysis to find structures which would increase the gain bandwidth for application in semiconductor optical amplifiers and broadband tunable lasers. A 10-band k.p Hamiltonian was used to calculate TE modal gain spectra. First, we calculated the gain spectra of a single quantum well for varying nitrogen compositions and well widths at fixed carrier density. Next, we calculated the gain spectra for two- and three-quantum-well systems which used the compositions and sizes of the previously analyzed single wells. The three-quantum-well system had an approximate 100% increase of gain bandwidth in comparison with a single quantum well. This increase is due to carefully selected different values of nitrogen compositions in various quantum wells. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)