Hybrid OFDM receiver assisted by a variable frequency comb

A physically assisted orthogonal frequency division multiplexing (OFDM) receiver is described and characterized. In contrast to recent reports that utilize two physically distinct frequency combs with Verniered frequency pitch, the new receiver topology relies on a single frequency-toggled frequency comb. Dual-comb photonic front end was replaced by a single comb split into two switched paths to achieve spectral decomposition. To demonstrate new receiver operation, hybrid RF-photonic architecture for discrete Fourier transform (DFT) was constructed and used to decompose a wideband RF signal. The receiver demodulated a 4-QAM OFDM channel using 50 carriers from a single frequency comb. OFDM channel, spanning 3-7.9GHz RF band, was encoded using 100MHz-separated subcarriers. OFDM receiver performance was quantified by measuring its error vector magnitude (EVM).