A 23.75-GHz frequency comb with two low-finesse filtering cavities in series for high resolution spectroscopy*
Hou Leia), Han Hai-Niana)†, Wang Weib), Zhang Longa), Pang Li-Huia), Li De-Huaa), Wei Zhi-Yia)‡
       
(a) Microwave spectrum of the photodetected pulse train after the first filter cavity via high-speed photodetector. The side modes are offset by 250 MHz from the 4.75 GHz are 27 dB below the peak. (b) The side-modes suppression at 23.75 GHz after the second filter cavity is approximately 43 dB.