Patent ID: 7515833

Claim:
A device, comprising: a first Mach-Zehnder interferometer modulator to receive a first optical carrier beam at a first optical carrier frequency and to modulate the first optical carrier beam in response to a plurality of first modulating signals at different first modulating frequencies to produce a first modulated optical beam carrying a plurality of pairs of first optical spectral components with the first optical carrier frequency being suppressed, wherein each pair of first optical spectral components include an upper-band optical spectral component at an upper-band optical frequency greater than the first optical carrier frequency by a corresponding first modulating frequency and a lower-band optical spectral component at a lower-band optical frequency less than the first optical carrier frequency by the corresponding first modulating frequency; a second Mach-Zehnder interferometer modulator to receive a second optical carrier beam at a second optical carrier frequency greater than the first optical carrier frequency and to modulate the second optical carrier beam in response to a plurality of second modulating signals at the different first modulating frequencies to produce a second modulated optical beam carrying a plurality of pairs of second optical spectral components with the second optical carrier frequency being suppressed, wherein each pair of second optical spectral components include an upper-band optical spectral component at an upper-band optical frequency greater than the second optical carrier frequency by a corresponding first modulating frequency and a lower-band optical spectral component at a lower-band optical frequency less than the second optical carrier frequency by the corresponding first modulating frequency, and wherein a lowest spectral component of the second optical spectral components in the second modulated optical beam is greater in frequency than a highest spectral component of the first optical spectral components in the first modulated optical beam; an optical coupler to combine the first and the second modulated optical beams into a combined modulated optical beam; and an optical filtering device to receive and to optically filter the combined modulated optical beam to transmit optical spectral components between the first and the second optical carrier frequencies and remove optical spectral components that are greater than the second optical carrier frequency and are less than the first optical carrier frequency.