A highly stable mm-wave synthesizer realized by mixing two lasers locked to an optical frequency comb generator

Millimeter signal generation with high spectral purity and low phase fluctuations up to 100 GHz were demonstrated with an optical method in which two external-cavity laser diodes were phase-locked to an electro-optic modulator (EOM)-based optical frequency comb generator (OFCG). The additional phase noise caused from the cavity fluctuation in OFCG was completely canceled, and the phase noise of the heterodyne beat note of two LDs was determined only by that of the signal generator below offset frequency of 10 kHz. The detailed investigation of such a high frequency signal had never been done before, and the measured frequency of 100 GHz was limited only by the bandwidth of the phase noise detection system, and can be expanded up to more than 1 THz. (C) 2004 Elsevier B.V. All rights reserved.