Simplified single-photodetector direct detection of independent dual-single-sideband OFDM signals

An independent dual-single-sideband (IDSSB) signal carries distinct data on its two optical sidebands, and conventional IDSSB receivers require two sideband-separation optical bandpass filters (OBPFs) and two photodetectors (PDs). We propose a simplified IDSSB direct-detection optical orthogonal frequency-division multiplexing (OFDM) scheme using one in-phase/quadrature (IQ) modulator and one PD together with a single noniterative digital signal processing (DSP) chain that recovers two independent left- and right-sideband quadrature phase shift keying (QPSK) OFDM streams from the synthesized 16-ary quadrature amplitude modulation (16-QAM) OFDM signal formed after photodetection. Simulations demonstrate 2 × 5.23-Gb/s transmission over 10-km standard single-mode fiber (SSMF), with the bit error rates (BERs) of both sideband signals below 3.8 × 10^-3. The optimum carrier-to-signal power ratio (CSPR) is found to be 2 dB. Compared with a conventional dual-OBPF/dual-PD receiver operating on the same transmitted waveform, the proposed receiver incurs an approximately 0.7-dB sensitivity penalty.