Terahertz carrier dynamics and application to all-optical wavelength conversion

We review the current state-of-the-art in four-wave mixing (FWM) based wavelength conversion as well as describing some of the interesting quantum-well physics that can now be probed by way of four-wave mixing spectroscopy. The FWM wavelength conversion process is shown schematically. An input signal that is carrying base band digital data is mixed with a pump wave in a semiconductor optical amplifier (SOA) and thereby generates a phase conjugate replica at a new frequency. Eye diagram analysis and bit error rate (BER) measurements for varying amounts of wavelength shift are presented, including results for record wavelength shifts by this technique.