Generation of highly stable millimeter waves with low phase noise and narrow linewidth

We present a novel stabilization technique for millimeter waves produced by interfering two spectral lines of a frequency comb generated by a femtosecond fiber laser. In order to compensate the lasers repetition rate drift, the mm-wave is stabilized via modulation of one extracted comb line. Thus, no access to the lasers cavity is necessary. This leads to a stable and high quality mm-wave with a spectral linewidth of 1 Hz and a phase noise of -134 dBc/Hz at 10 kHz carrier offset via software stabilization technique. The long term stability shows a drift of the generated frequencies as low as 1 Hz over more than 40 minutes with an analog circuit.