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Abstract Large crystal growth and characterization of the optical and terahertz (THz) properties of organic nonlinear optical (NLO) crystal NMBA (4‐Nitro‐4′‐methylbenzylidene aniline) is presented. The reported method of crystal growth consistently produces high‐quality single crystals. The THz generation efficiency and optical properties of NMBA to other THz generation crystals including BNA and MNA are compared. The low THz absorptions that make NMBA an ideal source for THz time‐domain spectroscopy are highlighted. 

Second-harmonic generation (SHG) is a common technique with many applications. Common inorganic single-crystalline materials used to produce SHG light are effective using short IR/visible wavelengths but generally do not perform well at longer, technologically relevant IR wavelengths such as 1300, 1550, and 2000 nm. Efficient SHG materials possess many of the same key material properties as terahertz (THz) generators, and certain single-crystalline organic THz generation materials have been reported to perform at longer IR wavelengths. Consequently, this work focuses on characterizing three efficient organic THz generators for SHG, namely, DAST (trans-4-[4-(dimethylamino)-N-methylstilbazolium] p-tosylate), DSTMS (4-N,N-dimethylamino-4’-N’-methylstilbazolium 2,4,6-trimethylbenzenesulfonate), and the recently discovered generator PNPA ((E)-4-((4-nitrobenzylidene)amino)-N-phenylaniline). All three of these crystals outperform the beta-barium borate (BBO), an inorganic material commonly used for SHG, using IR pump wavelengths (1200–2000 nm). 

We have improved the THz output and damage threshold of yellow organic THz generation crystals by fusing them to sapphire and using liquid crystals as index matching fluid to reduce reflective losses. 

We generate tunable narrowband THz radiation using BNA bonded to sapphire in tandem with a chirp and delay technique. Using a Ti:Sapphire laser, we test the limits of intense THz generation (0.1 to 5 THz). 

We present the optical and THz properties of highly efficient organic nonlinear optical crystals PNPA and MNA. These crystals outperform industry standards in broadband THz generation through optical rectification of IR light pulses.