Flat, rectangular frequency comb generation with tunable bandwidth and frequency spacing.

The generation of flat, rectangular frequency combs with tunable frequency spacing and bandwidth is demonstrated. Therefore, several lines or sidebands are extracted out of an existing frequency comb, for example a femtosecond fiber laser. Subsequently, these lines are processed via two Mach-Zehnder modulators in order to generate a flat frequency comb with tunable frequency spacing.

Generation of ultra-narrow, stable and tunable millimeter- and terahertz- waves with very low phase noise.

The interference between two spectral lines of the frequency comb of a fiber femtosecond laser is used to generate millimeter-wave and terahertz tones. The two lines are selected by stimulated Brillouin scattering (SBS) amplification. All other modes are strongly rejected based on polarization discrimination, using the polarization-pulling effect that is associated with SBS.