A new method for terahertz signal generation using Kelly sidebands of mode-locking fiber laser

Abstract A new method for generation of terahertz (THz) signal by using the ±1 order Kelly sidebands of mode-locking (ML) fiber laser is proposed. A physical model is built up to characterize the sidebands. In experiment, the ±1 order Kelly sidebands with large and small spacing were obtained from two lab-made ML fiber lasers operating at 1550 nm and 1064 nm wavebands, respectively. By photomixing the ±1 order sidebands, experimental result showed that desired THz signals were generated at frequencies of 0.914THz and 0.187THz from the two lasers. It is found that the total dispersion and filtering bandwidth of the grating used in the laser cavity play significant roles in determining spacing and intensity of the ±1 order Kelly sidebands, which correspond to frequency and intensity of generated THz signals. Besides, bandwidth and stability of the ±1 order Kelly sidebands are investigated both theoretically and experimentally for their influence on the THz signal generation.