Rainbow Photonics: Growth of Nonlinear Optical DAST Crystals

Abstract

DAST (4-N,N-dimethylamino-4'-N'-methyl stilbazolium tosylate) is an organic salt with one of the highest nonlinear optical susceptibilities and electro-optical coefficients. DAST crystals are therefore seen as good candidates for many photonic applications such as microring resonators or for THz-devices. The quality of such organic crystal is crucial for any application. We discuss here two different growth methods of single crystalline DAST from solution. Bulk crystals, 1 cm3 in size, and thin crystals, 1 mm2 for a thickness of about 100 ?m are obtained. The use of a DAST crystal for a microring resonator is also presented

Investigation on rapid growth of 4-N,N-dimethylamino-4′-N′-methylstilbazolium p-toluenesulphonate (DAST) crystals by SNM technique

“…The experiments conducted by Han et al [17] proved that DAST crystals with a thickness of a few hundred micrometers are suitable for EO sampling up to few THz. It has been reported that the as-grown and very thin crystals are less sensitive to thermal shock when compared to thick DAST crystals due to large thermal gradients and these thin DAST crystals are preferable to avoid defects [18]. Recently, the as-grown nonpolished DAST crystal was used successfully for THz generation by Taniuchi et al [19].…”

Large‐Size Bulk and Thin‐Film Stilbazolium‐Salt Single Crystals for Nonlinear Optics and THz Generation

“…Up to date, DAST is the only commercially available organic nonlinear optical crystal. [12] However, its growth is still a challenge and there are many groups investigating the growth of bulk and thin films of DAST. [13][14][15][16] For example, one of the challenges is to reduce the growth time needed to obtain high optical quality DAST, which takes several weeks for crystals with dimensions exceeding 1 cm 3 .…”

“…[13][14][15][16] For example, one of the challenges is to reduce the growth time needed to obtain high optical quality DAST, which takes several weeks for crystals with dimensions exceeding 1 cm 3 . [12] Although DAST shows large electro-optic effects, the development of new organic crystals with larger electro-optic coefficients and (or) faster and easier crystal growth procedure is an important challenge for future applications. It has already been demonstrated that varying the counter-ion to optimize the crystal packing and orient the dipoles as parallel as possible is an effective molecular engineering strategy to develop ionic organic crystals with non-centrosymmetric structure.…”

Twin-free and High-Quality DAST Crystals − Effected through Solutions of Lower Supersaturation Coupled with Isothermal Solvent Evaporation

“…In addition, Laveant et al, while exploring a different approach to grow thin DAST crystals, stated that as-grown and very thin DAST crystals (about 80 µm thick) possess a two-dimensional (2D) aspect ratio since they are less sensitive to thermal shock (during growth), which is observed for thick DAST crystals due to large thermal gradients, and that these thin DAST crystals are preferable to avoid extended defects such as twinning and cracks. 8 Thus, the aforementioned aspects show that high-quality crystals with a few hundred microns thickness are sufficient to achieve the target. These crucial aspects, obviously, warrant an effective approach to identify a suitable method.…”

“…Interestingly, Taniuchi et al have shown that as-grown and nonpolished DAST crystals with dimensions of 3 × 3 × 0.5 mm 3 grown by SNM with both surfaces flat are sufficient for the efficient generation of THz waves. In addition, Laveant et al, while exploring a different approach to grow thin DAST crystals, stated that as-grown and very thin DAST crystals (about 80 μm thick) possess a two-dimensional (2D) aspect ratio since they are less sensitive to thermal shock (during growth), which is observed for thick DAST crystals due to large thermal gradients, and that these thin DAST crystals are preferable to avoid extended defects such as twinning and cracks . Thus, the aforementioned aspects show that high-quality crystals with a few hundred microns thickness are sufficient to achieve the target.…”