Abstract

Two mechanisms have been shown to cause non-degenerate four-wave mixing (NDFWM) in semiconductors.^1-3 One is carrier density modulation caused by interband photomixing of pump fields. A second is ultrafast gain saturation caused by intraband dynamics, also referred to as the gain nonlinearity effect. At ultra-high frequencies, well beyond the interband relaxation rate, it can dominate the NDFWM process. Apart from its importance to NDFWM, the nonlinear gain effect has a significant impact on semiconductor laser modulation dynamics. However, the physical mechanisms causing the gain nonlinearity are still not fully understood.

© 1993 Optical Society of America