Generation of efficient THz radiation by optical rectification in DAST crystal using tunable femtosecond laser pulses

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• 作者：Mottamchetty Venkatesh ; K. Thirupugalmani ; K. S. Rao…
• 关键词：Terahertz ; DAST ; Optical rectification ; Pyroelectric detector ; Photoconductive antennas ; THz band pass filters
• 刊名：Indian Journal of Physics
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：91
• 期：3
• 页码：319-326
• 全文大小：
• 刊物类别：Physics and Astronomy
• 刊物主题：Physics, general; Astrophysics and Astroparticles;
• 出版者：Springer India
• ISSN：0974-9845
• 卷排序：91

文摘

We report the efficient THz generation by optical rectification from an indigenously grown organic DAST crystal using the 140 fs oscillator laser pulses tunable in between 780 and 850 nm. The generated THz pulse profile and powers have been measured using the photoconductive (PC) antennas and pyroelectric detector, respectively. The highest THz peak amplitude and power is obtained at 825 nm central wavelength. We have theoretically explained the enhancement of THz radiation based on the matching of average optical group refractive index and average THz refractive index of the DAST crystal at 825 nm. In addition, the dependence of THz peak amplitude and THz power on laser power have been carried out. The measured quantum conversion efficiency (QCE) of 0.5 and 1.5 THz bands are of the order 3.7 × 10−3, 1.4 × 10−3, respectively. Finally, an attempt has been made to study the effect of polarizations on generated THz signal.