Maximizing spectral utilization in WDM systems by microwave domain filtering of tandem single sidebands

We present an optical tandem single-sideband receiver that enables the detection of signals having different information in the two sidebands of the same optical carrier. The technique relies on the use of a dual-electrode Mach-Zehnder modulator and achieves heterodyne detection without the use of an optical local oscillator. Sharp filtering requirements are met in the electrical domain, eliminating the need for wasteful guardbands.