| Terahertz(THz)wave has been widely used in many areas including security check,nondestructive detection,medical and astronomy.However,THz applications were limited by the low output power of THz source and difficulty of regulation.It is essential to obtain THz source with high pulse energy and effective modulation method.In this paper,modulated THz wave was obtained by two-beam pumping or using slit to intercept pump pulses based on the spatio-temporal chirp introduced with pulse-front tilt.The main contents are as follows:1.Introduction for characteristics and applications of THz wave,as well as methods on generation and detection of THz wave.In addition,the current status of tilted-pulse-front pumping is reviewed.2.The principle of THz wave generated by pumping nonlinear crystals via optical rectification(OR)is introduced.Factors on THz conversion efficiency are analyzed based on the formula of OR.3.THz wave was generated by two-beam pumping and TPFP.Bandwidth and center frequency of THz spectrum were modulated by tuning time delay within two-beam coherent range based on the temporal chirp introduced with pulse-front-tilt(PFT).Modulated THz wave were obtained by spectral interference at large time delay beyond the coherent range.At the condition of two-beam synchronized,THz output power realized almost 4 times enhancement compared with single-beam pumping.Besides,by utilizing 1-mm slit to intercept the pump pulses,tuned THz wave was obtained in the range of THz spectrum generated via directly pumping.4.THz wave was produced by pumping Ga P crystal via spatial chirp pulses.Two1-mm slits was used to intercept pump pulses and THz wave,respectively.Comparing the THz spectrum obtained by two interceptions,relationship between spatial chirp pulses and chirped THz wave was confirmed.It demonstrated that complete THz wave was the superposition of THz waves generated by each part of the spatial chirp pulses... |
PDF Full Text Request