Patent ID: 7486896

Claim:
A method to recover at least one optical clock frequency associated with an optical signal, said optical signal comprising a first data signal, and a second data signal, said method comprising: coupling said optical signal to an optical resonator, setting one of the pass bands of the optical resonator substantially to a spectral peak of the first data signal, selecting the separation range of said optical resonator such that a clock frequency of the first data signal is substantially equal to the separation range of the optical resonator multiplied by a first integer greater than or equal to two, and such that a separation between said spectral peak of the first data signal and a spectral peak of the second data signal is substantially equal to the separation range of the optical resonator multiplied by a second integer; and coupling an output signal out of said optical resonator, wherein said output signal comprises a beat signal having a beat frequency that is equal to the clock frequency of said first data signal, and wherein a spectral position of said beat signal coincides with spectral components of said first data signal.