- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Optical Generation of High-power Terahertz Pulses for Tunable Wave Source
摘要： High-power terahertz pulse generation and its polarization and frequency control by optical rectification with nonlinear organic crystals were studied. Terahertz pulses up to 730 nJ/pulse was generated from a DAST crystal pumped by 250 μJ femotosecond laser pulses with a central wavelength of 1500 nm. The terahertz peak electric field is estimated as 860 kV/cm if we focus the terahertz beam to φ=300 μm spot, which is expected to nonlinear material control application. We proposed the high-power terahertz polarization pulse shaping using the double stacked nonlinear organic crystals excited with tailored pump pulses. Through the terahertz modulation of pump pulses, the waveform shaping of the high-power terahertz pulses are expected, which leads to selective excitation of molecules or spin waves.
关键词： optical rectification,terahertz pulses,nonlinear organic crystals,polarization control,DAST crystal
更新于2025-09-23 15:21:01
-
Growth of 4-N,N-Dimethylamino-4'-N'-methyl-stilbazolium Tosylate (DAST) Organic Single Crystals Controlled by Oleic Acid
摘要： 4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST) organic single crystals controlled by (Z)-Octadec-9-enoic acid (oleic acid, OA) was grown by a slow-cooling method. The as-grown DAST single crystals were systematically characterized by FTIR, X-ray diffraction, second harmonic generation, and UV-vis spectroscopy. Results indicate that addition of OA into the DAST solutions leads to the controlled growth of DAST single crystals and consequently, the crystal quality and optical properties can be modified. Particularly, the DAST crystals grown under the control of OA exhibit larger sizes, higher crystallinities, and better optical qualities with higher optical band gaps and lower defect density, compared with those grown in the absence of OA. These results are helpful for better understanding the controlled growth of DAST organic single crystals and modifying their properties for practical applications.
关键词： nonlinear optical materials,crystal growth,additives,DAST single crystals
更新于2025-09-16 10:30:52
-
Electrically controlled growths of 4-N,N-dimethylamino-4a?2-Na?2-methyl-stilbazolium tosylate (DAST) organic microcrystals
摘要： 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium tosylate (DAST) is one of the most important organic nonlinear optical (NLO) materials, but its controlled growth remains a challenge. Herein, we describe a novel method to control the growth of DAST on the surfaces of indium tin oxides coated with the patterned photoresists by electric field. Results indicate that zero-dimensional (0D) spherical DAST microcrystals tend to grow along the photoresist lines if an electric field with a low frequency of 500 Hz is applied. Rather differently, one-dimensional (1D) DAST microwires preferentially grow along the gaps of the photoresist lines under the control of an electric field with a high frequency of 1000 Hz. Growth of DAST microcrystals controlled by electric field leads to the increase in the crystallinity, but the chemical structures remain unchanged. Moreover, second harmonic generation signal was measured from the as-grown DAST microcrystals. The results presented in this work are helpful for rationally controlling the growth of 0D or 1D DAST microcrystals, and particularly, the strategy can be further expanded to control the growth of DAST derivatives or other organic NLO materials with similar chemical structures.
关键词： Spectral analyses,Growth mechanism,Electric field induction,DAST microcrystals,Nonlinear optical material
更新于2025-09-16 10:30:52
-
Photobleaching of Submicron DAST Crystals in a PMMA Film by Direct Laser Writing
摘要： Selective photobleaching of DAST (trans-4'-(dimethylamino)-Nmethyl-4-stilbazolium tosylate) non-linear crystals in a 2-μ m-thick polymethacrylate film using direct laser writing at a wavelength of 532 nm at a power of 1–10 mW and a recording speed of 5–35 μ m/s is studied. The laser pattern is established as a function of recording parameters. The destruction of crystals and their transition into the amorphous state enabled one to record a structure that is well resolved in the optical microscope and in the luminescence signal. No layer surface violation at the crystal damage sites is detected. The method ensures the formation of a grating with a periodic modulation of the nonlinearly optical coefficient, which is essential in the quasi-phasematching generation.
关键词： nonlinear optics,DAST,2D grating,photobleaching
更新于2025-09-12 10:27:22