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N-Benzyl-2-methyl-4-nitroanaline (BNA) is currently the industry standard for terahertz generation at 800 nm using organic materials. We developed four derivatives of BNA by replacing a hydrogen atom on the benzyl substituent with either a fluorine (F-BNA), a methoxy group (MeO-BNA), a cyano group (CN-BNA), or a methyl group (Me-BNA). X-ray diffraction measurements confirmed that all derivatives were crystallized in the same space group as BNA (Pna21). The THz generation capability of F-BNA is higher than that of BNA, with the maximum Fourier amplitude increasing by an average of 14% when pumped with wavelengths of 800, 1250, and 1550 nm. The damage threshold of F-BNA was also found to be higher than that of BNA, increasing by a factor of 1.14. The phase matching of F-BNA and BNA was found to be comparable. The increased THz output is, therefore, likely due to the higher induced nonlinear polarization, molecular hyperpolarizability, and closer molecular packing of F-BNA compared to BNA.
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Characterization of organic crystals for second-harmonic generation
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).
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- Award ID(s):
- 2104317
- PAR ID:
- 10472393
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Letters
- Volume:
- 48
- Issue:
- 22
- ISSN:
- 0146-9592; OPLEDP
- Format(s):
- Medium: X Size: Article No. 5855
- Size(s):
- Article No. 5855
- Sponsoring Org:
- National Science Foundation
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