Large-Size Pyrrolidine-Based Polyene Single Crystals Suitable for Terahertz Wave Generation

Abstract

We report on the growth of large pyrrolidine-based polyene single crystals from methyl ethyl ketone (MEK) solutions for nonlinear optical applications. The polyene crystals grown exhibit a suitable morphology and surface roughness and good optical quality. We successfully demonstrated THz wave generation with as-grown polyene crystals. Although the crystal cut was not optimized and phase-matching conditions were not fulfilled, we achieved a similar or higher THz generation efficiency compared to the well-known inorganic ZnTe emitter crystals.

Highly Efficient Organic THz Generator Pumped at Near‐Infrared: Quinolinium Single Crystals

“…The parallel surfaces are along the b crystallographic planes, which means that the polar c ‐axis is in the plane as shown in Figure 7b. Therefore, compared to the morphology of HMQ‐MBS crystals with non‐parallel surfaces, as‐grown HMQ‐T crystals are more suitable for THz wave generation 13…”

“…We generated THz waves by using optical rectification (OR) using femtosecond‐laser pump pulses in various nonlinear optical crystals, and detected these waves by the electro‐optic sampling (EOS) method 13. We used fundamental optical pulses with a duration of 170 fs at 836 nm with repetition rate of 1 kHz from a regenerative amplified Ti:sapphire laser.…”

“…Presently, inorganic crystals such as ZnTe and GaAs are the most popular THz sources for these techniques 3, 8. Recently, using organic electro‐optic crystals, a great improvement in THz generation and detection has been demonstrated 9–15. The state‐of‐the‐art ionic organic crystals based on dimethylamino‐stilbazolium16, 17 and non‐ionic configurationally locked polyene (CLP) groups4, 12, 13, 18, 19 exhibit a large macroscopic nonlinearity with largest diagonal electro‐optic coefficients of up to r = 53 pm V ‐1 at 1.3 μm,20, 21 while inorganic ZnTe crystals have r 41 = 4.1 pm V ‐1 12.…”

“…Recently, using organic electro‐optic crystals, a great improvement in THz generation and detection has been demonstrated 9–15. The state‐of‐the‐art ionic organic crystals based on dimethylamino‐stilbazolium16, 17 and non‐ionic configurationally locked polyene (CLP) groups4, 12, 13, 18, 19 exhibit a large macroscopic nonlinearity with largest diagonal electro‐optic coefficients of up to r = 53 pm V ‐1 at 1.3 μm,20, 21 while inorganic ZnTe crystals have r 41 = 4.1 pm V ‐1 12. The larger macroscopic nonlinearities of organic stilbazolium and CLP crystals, compared to inorganic crystals, result in significantly larger THz generation efficiency, with over one order of magnitude larger figure of merit for THz generation: 4200 (pm V ‐1 ) 2 for DAST ( N,N ‐dimethylamino‐ N ’‐methylstilbazolium 4‐methylbenzenesulfonate), 4300 (pm V ‐1 ) 2 for DSTMS ( N,N ‐dimethylamino‐ N ’‐methylstilbazolium 2,4,6‐trimethylbenzenesulfonate), 5300 (pm V ‐1 ) 2 for OH1 (2‐[3‐(4‐hydroxystyryl)‐5,5‐dimethylcyclohex‐2‐enylidene]malononitrile), 370 (pm V ‐1 ) 2 for ZnTe and 86 (pm V ‐1 ) 2 for GaAs 12, 19…”

Pd‐Promoted Homocoupling Reactions of Unsaturated Silanes in Aqueous Micelles

“…[9] The significance of polyenes in studies dealing with organic electronics is manifold: conjugated polyenes have been investigated as molecular conductors [10] and switches, [11] optical conductors, [12] optical diodes, [13] and nonlinear optical (NLO) materials. [14] Moreover, due to their well-defined chemical structure and possibility of selective functionalization, they represent valuable model systems for validation of predictions based on theoretical calculations and for developing new concepts in organic electronics. [15] …”