兆赫頻段下之磁流體光學常數探討

Terahertz Optical Properties of Ferrofluid

邱奕傑(Ciou Yi-Jie)

指導教授 ： 楊承山

國立臺灣師範大學/科技與工程學院/光電工程研究所/碩士(2020年)

https://doi.org/10.6345/NTNU202000353

摘要

磁流體為一種可以利用磁場進行控制的智能奈米流體，因為磁流體的光學、熱學、流變性質可以達到精準地控制因此被歸類為智能流體，其應用在工業上包含了無洩漏密封[1][2]、軸承潤滑液[3]，其軸承間具有磁力使得磁流體能夠完美的包覆在軸承之間達成無洩漏的密封狀態並且可以降低軸承之間的摩擦力並且此應用也在噴墨列印機上展現出優良的打印能力[4]，並且在光學上也根據其調節優越的特性成功製成了良好的光柵[5]並且對於施加不同強度的磁場還能夠產生對不同波長下使用的光學濾波片[6]，在生物醫療上因為其操控能力優越以外，磁流體的表面活性劑還能夠與生物分子的鍵結產生配對，諸如:生物感測器[7]、醫療診斷[8]、標靶治療[9]等等[10]。隨著網路技術的發達，我將研究在兆赫波段中鮮少被使用的磁光效應調制器來應對新網路時代的來臨，由於能夠在兆赫波段下產生磁光效應的材料需要斟酌，我將利用四氧化三鐵的磁流體在不同的平行磁場強度下的磁光特性對兆赫波段進行調制，藉由磁光效應所帶來的折射率變化對兆赫波產生有效的調制成果。
本論文將使用以ZnTe晶體作為兆赫波發射源的兆赫波時域光譜系統，利用高尖峰功率的飛秒雷射激發晶體產生出兆赫波並且也利用ZnTe作為兆赫波偵測器，通過離軸拋物面鏡將兆赫波導入樣品中心，最後藉由四分之一波片與Wollaston prism整理兆赫波訊號接收至光偵測器，藉由兆赫波通過前樣品與通過後的變化得出此樣品在兆赫波段的穿透率為何再以兆赫波的色散與振幅變化推算出樣品的折射率與消光係數。本研究使用親水性磁流體與親油性磁流體做出比對，以得證親油性磁流體對於兆赫頻段具有顯卓的表現。

關鍵字

ZnTe配置的兆赫波時域光譜 ； 飛秒雷射 ； 磁流體 ； 兆赫波磁光調制器

並列摘要

Ferrofluid is a smart nanofluid that can be controlled using a magnetic field. Because the optical, thermal, and rheological properties of magnetic fluids can be precisely controlled, it is classified as a smart fluid. Its application in the industry includes leak-free sealing [1 ] [2], bearing lubricating fluid [3], there is magnetic force between the bearings so that the magnetic fluid can be perfectly covered between the bearings to achieve a leak-free sealed state and can reduce the friction between the bearings and this application is also spraying Ink printers have demonstrated excellent printing capabilities [4], and optically have successfully made good gratings [5] according to their excellent adjustment characteristics, and can also produce different wavelengths at different wavelengths for applying magnetic fields of different strengths. The optical filter used [6], in addition to its superior handling ability in biomedicine, Ferrofluid surfactants can also be paired with biomolecule bonds, such as: biosensors [7], medical diagnosis [8] ], Target therapy [9], etc. [10]. With the development of network technology, I will study magneto-optic effect modulators that are rarely used in Terahertz to cope with the advent of the new Internet era. Since materials capable of generating magneto-optical effects under Terahertz need to be considered, I will use Fe3o4 The magneto-optical properties of the Ferrofluid produced under different parallel magnetic field intensities modulate Terahertz, and the refractive index changes caused by the magneto-optical effect produce effective modulation results for Terahertz waves.
In this paper, a Terahertz time-domain spectroscopy system using a ZnTe crystal as a Terahertz emitter will be generated using a femtosecond laser with a high peak power to generate a Terahertz wave. The Terahertz wave will also be used as a Terahertz detector by ZnTe. Introduced into the sample center, and finally the Terahertz signal was received by the quarter wave plate and Wollaston prism to receive the light detector. The Terahertz wave passed the sample before and after the change to determine the transmittance of this sample in Terahertz. The refractive index and extinction coefficient of the sample were calculated based on the dispersion and amplitude changes of the Terahertz wave. In this study, a comparison was made between the hydrophilic Ferrofluid and the lipophilic Ferrofluid.

並列關鍵字

ZnTe-configured Terahertz time-domain spectroscopy ； femtosecond laser ； ferrofluid ； Terahertz Magneto-Optical modulator

參考文獻

[1] Odenbach, Stefan. "Recent progress in magnetic fluid research." Journal of physics: condensed matter 16.32 (2004): R1135.

[2] Ochoński, W. "Dynamic sealing with magnetic fluids." Wear 130.1 (1989): 261-268.

[3] R. Moskowitz, P. Stahl, and W. R. Reed, Ferrofluidics Corporation, assignee, Dynamic lip seal using ferrofluids as sealant/lubricant, United States Patent 4,171,818, October (1979).

[4] K. Raj, B. Moskowitz, and R. Casciari, J. Magn. Magn. Mater. 149, 174 (1995).

[5] Pu, Shengli, et al. "Tunable magnetic fluid grating by applying a magnetic field." Applied Physics Letters 87.2 (2005): 021901.