似噪音與鎖模脈衝以光整流機制產生兆赫輻射之比較研究

A comparative study of Terahertz signal generation by optical rectification using mode-locked and noise-like pulses.

蔡昀展(Yun-Chan Tsai)

指導教授 ： 潘犀靈

國立清華大學/電機資訊學院/光電工程研究所/碩士(2021年)

摘要

在本論文中，我們利用非線性光學理論以及龍格-庫塔法模擬分析碲化鋅晶體中光整流效應產生兆赫茲的過程。為理論分析,二階非線性效應是通過使用慢變包絡近似的波動方程。在類似的光學參數條件下入射鎖模脈衝和似噪音脈衝，比較兩者對厚度25微米碲化鋅中產生兆赫輻射訊號的差異。脈衝能量為微焦耳等級下產生的兆赫茲頻譜，在5.3~6.9兆赫茲處有強兆赫茲吸收，且似噪音脈衝產生者會比用鎖模脈衝的寬約2-4個兆赫，頻譜最高可接近50兆赫茲，能量則略低於鎖模脈衝產生者，約在10-13焦耳等級。不過，鎖模脈衝產生之兆赫茲訊號的能量可至10-12焦耳等級。

關鍵字

兆赫茲輻射 ； 鎖模脈衝 ； 似噪音脈衝 ； 光整流效應

並列摘要

In this paper, we use nonlinear optics and Runge-Kutta method to simulate and analyze the process of generating terahertz radiation by the optical rectification effect in zinc telluride crystals by mode-locked pulse (MLP) and noise-like pulse (NLP). For theoretical analysis, the second-order nonlinear effect is considered. Further, the slowly varying envelope approximation is assumed to be valid. Comparing the terahertz spectrum generated by MLP and NLP with pulse energy at microjoule level in a zinc telluride capital. The noise-like pulse THz generator will be about 2 to 4 THz wider than that by the mode-locked pulse. Strong THz absorption at 5.3 to 6.9 THz is predicted, as expected from the phonon resonance. The spectrum can be as broad as 50 THz. THz pulse energy generated by NLP is slightly lower than that by the mode-locked pulse generator, at the level of 10-13 Joule level. About an order of magnitude lower.

並列關鍵字

terahertz radiation ； mode-locked pulse ； noise-like pulse ； optical rectification

參考文獻

[1] J. Uddin, Terahertz Spectroscopy: A Cutting Edge Technology. BoD–Books on Demand, 2017.

[2] C. Fattinger and D. Grischkowsky, "Terahertz beams," Applied Physics Letters, vol. 54, no. 6, pp. 490-492, 1989.

[3] P. R. Smith, D. H. Auston, and M. C. Nuss, "Subpicosecond photoconducting dipole antennas," IEEE Journal of Quantum Electronics, vol. 24, no. 2, pp. 255-260, 1988.

[4] M. Van Exter, C. Fattinger, and D. Grischkowsky, "Terahertz time-domain spectroscopy of water vapor," Optics letters, vol. 14, no. 20, pp. 1128-1130, 1989.

[5] H.-J. Song and T. Nagatsuma, "Present and future of terahertz communications," IEEE transactions on terahertz science and technology, vol. 1, no. 1, pp. 256-263, 2011.