Recentprogressesaboutopticalpumpedtunableterahertz(THz)sourcesareinterviewed,includingTHzparametricoscillation(TPO)anddifferencefrequencygeneration(DFG).Wedevelophighefficiencyandhighpowersurface-emittedTPO,aswellasDFGwithnonlinearcrystals.AnovelschemeforthehighefficiencyDFGsourcebasedontheCherenkovphase-matchingtechnologyiscomprehensivelyinvestigatedinbothbulkcrystals.ThewidelytunableopticalTHzradiationisalsoresearchedbasedontheorganicnonlinear4-N,N-dimethylamino-4′-N′-methylstilbazolium2,4,6-trimethylbenzenesulfonate(DSTMS)crystal.
