Photonic Down-Conversion of Millimeter Wave Multiband Orthogonal Frequency Division Multiplexing Ultra-Wideband Using Four Wave Mixing in an Electro-Absorption Modulator

We propose and demonstrate a novel and cost-effective photonic down-conversion scheme for millimeter wave (mm-wave) over fiber (MoF) uplinks using an electro-absorption modulator (EAM) at a base station. Two wavelengths with frequency difference of f_lo, used as dual wavelength, are incident to an EAM that is driven by an mm-wave signal at f_mm to obtain optical subcarrier modulation. Due to four-wave mixing (FWM), two new wavelengths are generated inside the EAM and used for the optical carriers for the uplink. One of the generated two wavelengths and one of two mm-wave signal subcarriers is separated by f_mm-f_lo in frequency, thus down-converted. Furthermore, down-conversion with tunability of optical carrier to optical subcarrier power ratio can be achieved by simply controlling the dual wavelength power into the EAM. We experimentally investigate the efficiency of the FWM versus EAM reverse bias voltage and input optical power. The performance of the proposed scheme for down-conversion of a 30 GHz multiband (MB) orthogonal frequency division multiplexing (OFDM) ultra-wideband (UWB) is also investigated in terms of error vector magnitude (EVM) versus RF and LO modulation index, and received optical power at the photodetector.