Millimeter-Wave Frequency Tripling Based on Four-Wave Mixing in a Semiconductor Optical Amplifier

An approach to generating a frequency-tripled millimeter-wave (mm-wave) signal based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) is experimentally demonstrated. In the proposed system, two phase-correlated optical wavelengths generated by an optical phase-locked loop (OPLL) are used as two pumps to generate the FWM process in the SOA. Two idlers with a wavelength spacing three times that of the two pump wavelengths are obtained. The two pump wavelengths are then removed by two cascaded fiber Bragg gratings serving as an optical notch filter. By beating the two idlers at a photodetector, an mm-wave with a frequency that is three times that of the OPLL reference source is generated