Optical Frequency Comb Generator

Scheme of the Optical Frequency Comb Generator: EOM=electro-optical modulator in optical cavity.

The electro-optical modulator in a mirror-cavity: The mirrors are directly on the surfaces of the electro-optical crystal. The modulation voltage at 10 GHz is applied to the crystal over a travelling-wave electrode, which length is adjusted so that the round-trip-time of the electrical wave is matched to that of the optical wave between the mirrors (Optical Comb Inc., Japan). 
The modulation introduces two sidebands of +-10 GHz to the laser line. Laser-line and sidebands are circulated in the cavity and modulated over and over again, so that more than 100 comb-lines are generated. 

Optical frequency comb generator, integrated into a rack-mounting box. Beat signal between all the comb lines at 10.000 GHz, detected with a fast photodiode with a 30dB-amplifier.The total comb power at the input of the optical power amplifier is about 0.2 mW. It can be amplified there up to 2 W.