Coherent optical frequency comb generation using an amplified fibre loop

The paper describes the generation of a coherent optical frequency comb (OFC) with more than 500 GHz bandwidth and a comb spacing in the lower GHz range. The comb source is based on an amplified fibre loop where phase locking is achieved using an optical phase modulator. Different to Mach-Zehnder based OFC generators a low modulation index for phase modulation was found to be sufficient for broadband comb generation. The structure of the used fibre loop is discussed in detail and results obtained during lab measurements are presented. The carriers of the optical frequency comb are meant to form the basis of a multi channel Radio-over-fibre system.