Comparison of two-wave and three-wave forward mixing in bismuth silicon oxide-theory and experiment

A comparison is made between the traditional two-wave amplification mechanism and a new mechanism that is due to forward three-wave mixing. It is found experimentally that considerably higher amplification is available using forward three-wave mixing. Experimental results are in good qualitative agreement with theory concerning dependence on frequency detuning and interbeam angle, but there is a discrepancy between experiment and theory relating to the magnitude of the gain obtainable by two-wave and three-wave mixing, respectively. It is suggested that an additional physical gain mechanism arising from large modulation effects should be included in the theory to account fully for the discrepancy between two-wave and three-wave results