Separation of coherent and incoherent nonlinearities in a heterodyne pump-probe experiment.
We demonstrate that the transient coherent nonlinearity (coherent artifact) affecting the pump-probe response of semiconductor optical amplifiers can be experimentally separated from the incoherent transient. The technique is based on measuring the mirror component of the coherent artifact which is a background-free four--wave mixing signal at a different frequency with respect to the transmitted probe in a heterodyne detection scheme. Measurements on amplifiers of different length reveal strong deviations from the commonly expected symmetric shape of the coherent artifact in case of long waveguides.
Borri
P
P
Romstad
F
F
Langbein
W
W
Kelly
A
A
Mork
J
J
Hvam
J
J