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We present new stilbazolium salt DSTMS (4‐N,N‐dimethylamino‐4′‐N′‐methyl‐stilbazolium 2,4,6‐trimethylbenzenesulfonate) with both high second‐order nonlinear optical properties and very favorable crystal growth characteristics. We are able to obtain very large area bulk single crystals of more than 3 × 3 × 0.2 cm3 with a high optical quality without using seed crystals by using low‐temperature solution growth. We also demonstrate the growth of single crystalline thin films of DSTMS with an area of up to 6 × 5 mm2 and a thickness between 5–30 μm. Nonlinear optical measurements reveal that DSTMS possesses large nonlinear optical susceptibilities with χ111(2) = (430 ± 40) pm V–1 at 1.9 μm. Highly efficient generation of broadband THz waves with THz electric field strengths of more than 4 kV cm–1 using 160 fs laser pump pulses at a wavelength λ = 1.45 μm and DSTMS crystals has been demonstrated.

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We report on the generation and detection of few-cycle THz pulses in the organic crystal DAST (4-N,N-dimethylamino-4'-N'-methyl stilbazolium tosylate) using the telecommunication wavelength 1.5 mum. A continuous spectrum from 1.3 to 4.8 THz was generated with a very high conversion efficiency (E(THz,max) ~ 50 kV/cm at an optical pump pulse energy of 25 muJ in a 0.6 mm thick crystal) using the high nonlinear optical susceptibility of DAST (chi (2)111 = 490 pm/V at lambda = 1535 nm) and velocity-matching observed in this material. Using a frequency-doubled probe beam at lambda = 750 nm, nearly velocity-matched detection can also be realized in ZnTe crystals, resulting in a continuous spectrum from 1.3 to 4 THz.

New organic nonlinear optical verbenone-based triene crystals have been developed, investigated and compared to analogous isophorone-based triene crystals studied previously. The verbenone-based crystals show molecular conformation and crystal structure similar to the analogous isophorone-based crystals and therefore retain large macroscopic nonlinearity and high thermal stability. However, other physical properties are improved; for example, the solubility in acetonitrile is about 2.5 times higher, and the melting temperature is about 13 °C lower, which are an advantage for solution and melt crystal growth, respectively. The verbenone-based crystals of sufficient size for bulk nonlinear optical applications, that is, 5 × 4 × 1.5 mm 3 , were successfully grown from acetonitrile solution by a slow evaporation method. Finally, terahertz (THz) absorption was measured in these crystals, and generation of THz waves was demonstrated.