Photonic microwave and mm-wave mixer for multichannel fiber transmission

Photonic microwave and millimeter wave (mm-wave) frequency conversion is a promising technique for future electronic systems due to its large bandwidth, electromagnetic immunity, and compatibility with other optical systems. However, the conversion gain of a photonic mixer is often low and may be further reduced by the fiber dispersion. In this paper, a photonic microwave and mm-wave mixer using an integrated polarization division multiplexing Mach-Zehnder modulator (PDM-MZM) is proposed, which exhibits the merits of high conversion gain, high purity, and compensation of the power fading in multichannel fiber transmission. By suppressing the optical carrier and optimizing the modulation index, the conversion gain and isolation are respectively improved by 27.6 and 55.3 dB in the experiment. After power compensation, high and relatively flat microwave and mm-wave signals from 12 to 45 GHz are obtained after transmission over 25-km fiber. In addition, an up-converted 38-GHz mm-wave signal carrying 100-MSym/s 16-quadrature amplitude modulation (16QAM) vector signal is simultaneously transmitted over four channels with different fiber length (back to back, 4, 25, and 50 km). The power fading in each channel can be independently compensated, and good electrical spectra, constellation diagrams, and receiver sensitivity are obtained.