| 摘要 |
The present application is directed to the measurement of the intensity and phase of high speed optical signals obtained by modulating an optical carrier, of frequency ωs, with a signal comprising three or more spectral modes, k=1, 2N, which are spaced apart from each other by a repetition rate, Ω. The optical signal has the form given in equation 1 and would seem to include optical frequency division multiplex signals. On reception of an optical signal of this type, the signal is heterodyned with an optical local oscillator signal, with frequency ωLO, produced by a tuneable laser. The local oscillator signal it tuned to lie between two of the modes. The heterodyned signal is passed through a photodetector to produce an electrical signal with components at three different beat frequencies, δ, Ω-δ, Ω. These components are isolated by filtering and used to measure the amplitude or/and phase of one of the modes. The tunable laser enables successive measurements to be taken across the optical spectrum allowing the system to measure extremely high bandwidth signals. |
