近年來,隨著太赫茲科技的發展愈來愈蓬勃,尤其因為太赫茲波的頻段特性能
夠實現對材料非離子化與非傷害性的檢驗,太赫茲波也逐漸應用在許多不同的
研究領域上,例如安全檢測與醫療成像等。其中,透鏡是在這些系統中非常重
要的元件之一,也因此有許多團隊已經開發出了不同規格的太赫茲透鏡以因應
各種條件。然而,這種傳統的球面透鏡容易有嚴重的像差,且過於厚重以至於
難以整合在太赫茲系統當中,因此,結合了超穎材料的太赫茲透鏡,或稱為
「超穎透鏡」,成為許多團隊的研究方向。超穎透鏡是一種輕薄的平面透鏡,並
且能經由調整結構達到不同的光學表現。在這篇論文當中,我們架設了一套頻
域太赫茲超穎透鏡的表徵與分析系統,利用太赫茲連續波發射器作為光源以及
太赫茲相機作為感測器,能夠即時且直接量測太赫茲超穎透鏡便分析其聚焦表
現。我們利用該系統量測了窄頻的矽基太赫茲超穎透鏡並建立了成像流程,從
所量測到的初始數據移除雜訊,並能夠繪製出焦平面的能量分布,且成功分析
該透鏡的聚焦能力,包含聚焦之光斑大小、聚焦效率、視場尺寸以及傳播方向
之能量分布。另外,我們也利用 3D 列印技術製作出了適用於不同頻段的太赫茲
透鏡並測量之,藉此確認該表徵系統的穩定性。

In recent years, the development of THz technology has become more vigorous.
Because the frequency band characteristics of THz waves can realize the non-ionization
and non-destructive testing of materials, THz waves are gradually applied in many
different research fields, such as security detection and medical imaging. The lens is
one of the critical components in the systems, and therefore many groups have
developed THz lenses with different specifications to cope with various conditions.
However, traditional spherical lenses are prone to severe aberrations and too thick to
be integrated with THz systems. Therefore, THz lenses combined with metamaterials,
or called "metalenses," have become the new research direction. A metalens is a thin,
flat lens that can achieve different optical performances by adjusting its structure. In
this thesis, we set up a frequency-domain THz metalens characterization and analysis
system, using a THz continuous wave emitter as a light source and a THz camera as a
sensor, which can instantly and directly measure and analyze the focusing performance
of the metalens. We used this system to measure narrow-band silicon-based THz
metalens and established an imaging process, which removed noise from the initial
measured data. In addition, we also used 3D printing technology to produce THz lenses
suitable for different frequency bands and measured them to confirm the stability of the
characterization system.

摘要...................................................... i
Abstract.................................................. ii
Acknowledgments........................................... iii
Table of Contents......................................... iiv
Lists of Tables........................................... vii
Lists of Figures.......................................... viii
CHAPTER I ................................................ 1
Introduction...............................................1
1.1 Motivation............................................ 1
1.2 Metamaterial, merasurface and metalens................ 2
1.3 THz characterization system .......................... 5
1.4 THz metalenses characterization ...................... 6
1.5 Thesis Overview....................................... 8
CHAPTER II.................................................10
THz measurement and characterization system................10
2.1 Overview of THz system................................ 10
2.2 Sample characterization in the THz range...............12
2.3 THz lenses characterization........................... 14
2.4 THz metalenses ....................................... 16
CHAPTER III................................................17
Measurement Setup and Imaging Processing ..................17
3.1 The Measurement system................................ 17
3.1.1 Photomixing......................................... 17
3.1.2 THz Camera.......................................... 18
3.2 Image formation....................................... 19
3.2.1 Gaussian noise...................................... 20
3.2.2 Linear noise correction............................. 21
3.2.3 Bad pixel removement.................................23
3.3 Spot analysis and lens characterization................24
3.3.1 Spot diameter .......................................25
3.3.2 Spatial profile .....................................27
3.3.3 Frequency shifting ..................................29
CHAPTER IV.................................................33
Silicon Metalens Characterization .........................33
4.1 Lens Design............................................33
4.2 Lens Fabrication ......................................34
4.3 Measurement and Characterization ......................35
4.3.1 Characterization at 1 THz ...........................36
4.3.2 Field of view (FOV) measurement .....................38
4.3.3 Characterization with frequency shifting.............42
4.4 Conclusion ............................................46
CHAPTER V..................................................47
3D Printed Metalens........................................47
5.1 3D Printing Operation Principle .......................48
5.2 Optical Properties of Printing Material................49
5.3 Design and Fabrication ................................55
5.4 3D printed Metalens characterization ..................56
5.5 3D printed THz flat lens characterization..............58
CHAPTER VI.................................................61
Conclusion and Future Work.................................61
6.1 Conclusion.............................................61
6.2 FutureWork.............................................61
Reference .................................................63

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