Frequency stabilisation of FDM optical signals

Frequency confinement of FDM optical signals to a comb of equally spaced frequencies has been demonstrated. The result was achieved by locking the frequencies of three optical sources to three different resonances of a fibre Fabry-Perot resonator. The frequency spacing between the frequency-locked signals was adjusted to be 500 MHz, the spacing between adjacent resonances, or a multiple of this value. Implementation of the frequency stabilisation circuit requires only a fibre Fabry-Perot resonator, a photodetector and simple electronics. Such a simple circuit provides the means to frequency-stabilise a large number of FDM optical signals originating from the same location.