A method of generating an information-bearing optical signal (614) from input digital information (602) includes generating (604, 606) an information-bearing electrical signal comprising an in-phase (I) component and a quadrature (Q) component. Each of the components has a predetermined baseband bandwidth requirement (B). The I and Q signal components are combined (610) with corresponding I and Q components of a radio frequency (RF) carrier (608). The carrier has a central frequency greater than the signal bandwidth requirement (B). An optical source is modulated (612) with the combined I and Q signal and carrier components, in order to produce a modulated optical signal (614) which comprises an optical carrier corresponding with the RF carrier, and substantially only a single information-bearing optical sideband in an optical frequency domain, corresponding with the information-bearing electrical signals. Transmitters implementing the method are also disclosed.