an rf - lightwave transmitter performs successive conversions of an information - bearing input signal in order to generate an output signal suitable for transmission in a wireless communications system . the transmitter includes a high - efficiency fm laser connected to a fm discriminator . in operation , the laser converts an rf signal into a frequency - modulated optical signal , and the discriminator converts this signal into an amplitude - modulated optical signal . the discriminator performs its conversion using a high slope - efficiency linear transfer function which ensures that the am optical signal varies in accordance with a desired operational performance . the transmitter also includes a photodiode which converts the am signal output from the optical discriminator back into an rf signal for transmission . experimental results demonstrated that a transmitter of this type is able to realize greater than 10 db rf insertion gain at less than 0 dbm optical power , with a high spurious - free dynamic range and low noise . a signal processor embodied within the transmitter may be used in a purely optical communication systems or may be used for other types of rf - photonics applications such as those expected for use in next - generation systems .