Frequency-Tunable Narrowband Time Domain Terahertz Wave Generation by Optical Rectification

摘要

During the last decades, narrowband terahertz (THz) radiation has attracted great interests in both fundamental and applied sciences. For many applications, the tunability of both central frequency and bandwidth of the narrowband THz radiation are required. In this paper, a simple scheme to generate high energy, frequency and bandwidth tunable multi-cycle THz pulses by optical rectification of femtosecond laser pulses in periodically poled lithium niobate (PPLN) crystal is proposed and demonstrated. The central frequency can be tuned by varying the incident angle between the pump beam and the domain walls of a periodically poled lithium niobate crystal. The opportunity of easily tuning the bandwidth of THz generation from about 20 GHz to a few THz exists by changing the pump spot size on PPLN crystal, and the energy spectral density of narrowband THz generation is almost independent of the bandwidth.