PROCEEDINGS ARTICLE | December 1, 2009
Proc. SPIE. 7632, Optical Transmission Systems, Switching, and Subsystems VII
KEYWORDS: Transmitters, Modulation, Receivers, Telecommunications, Orthogonal frequency division multiplexing, Signal detection, Tolerancing, Systems modeling, Double sideband modulation, Single sideband modulation
In-phase/quadrature-phase (IQ) imbalance can result in severe performance degradation in optical direct-detection
orthogonal-frequency-division-multiplexing (DD-OFDM) systems. We build two optical back-to-back DD-OFDM
systems, which implement double-sideband (DSB) and single-sideband (SSB) modulation, respectively. The tolerance to
IQ imbalance of these two systems is analyzed and compared using error vector magnitude (EVM) and symbol error rate
(SER). We find that, in the back-to-back case, the DSB system has stronger robustness to IQ imbalance than the SSB
System. We further build two optical DD-OFDM systems each with 40-km transmission, which respectively implement
DSB and SSB transmission. Similarly, we analyze and compare the tolerance to IQ imbalance of these two systems in
terms of EVM and SER. We find that, however, in the case of 40-km transmission, the SSB system has stronger
robustness to IQ imbalance than the DSB system. As a result, we conclude that, in the case of transmission, SSB
modulation can enhance the tolerance to IQ imbalance of DD-OFDM systems.
