Cross-talk-induced limitations of two-pump optical fiber parametric amplifiers

We have investigated the generation of new undesirable frequencies in a two-pump optical parametric amplifier, which are generated by the four-wave mixing of a signal or idler with one of the strong pump waves. The powers of the new frequencies impose upper bounds on the device gain and output power if cross talk is to be avoided. In the parametric amplifier we investigated, however, we found that, for 7.5 dB of gain and -3.5 dBm of output power, the ratio of power in the new frequencies and the signal is less than -30 dB. This demonstrates that cross talk is acceptable for low gain and output power applications of these devices such as frequency conversion. We present simple scaling relationships for the power in the new undesirable frequencies that can be used to help design optical parametric amplifiers. (C) 2004 Optical Society of America