Abstract
We demonstrated that an electro-optic-modulation (EOM) comb can work as a noise booster and a highsensitivity
detector for detecting the magnified noise from microwave and millimeter-wave signal
generators (SGs). Our method can generate low-noise and continuously frequency-variable microwave
and millimeter-wave signals. In addition, we can overcome the disadvantage of the EOM comb. The
noise in 25-GHz signals can be reduced to ‒110dBc/Hz at a 1-kHz offset frequency from the center
frequency. The noise with our method is one-hundred times lower than the lowest noise reported for
commercially available SGs. Even lower noise will be achieved if we use a reference laser that is further
away from the center frequency of the seed laser. In addition, the output frequency of microwave and
millimeter-wave signal generators can be expanded for their universal use. We succeeded in generating
low-noise signals at continuously variable frequencies over the range from 6 to 72 GHz.
