電漿子超穎介面於全彩全像片與電調控光學元件之應用

現今視覺的科技日新月異，色彩三原色分光與偏振選擇為主要範疇。液晶顯示器或數位微鏡裝置組成的全像片以純量光學為基礎，不具有偏振選擇性。超穎材料或超穎介面則以表面電磁場的純量光學為基礎，在次波長維度下調控光的振幅、相位與偏振性，並廣泛應用於寬頻、寬角度、偏振選擇性相位全像片。然而，目前超穎材料或超穎介面之工作範圍因為材料限制，難以設計在可見光波段，寬頻工作的超穎材料或超穎介面也難以達到波長分波多工。另一方面，光訊息可藉由振幅、相位、偏振、頻率、或結合其中幾項來記錄與調控。以晶片基礎的表面電漿調控器結合奈米尺度的表面電漿結構與光子學元件組合而成，具有最快調控速度與需要最少單位訊號所需能量的優點。由次波長人造材料的超穎介面具有非凡的光調控特性，在廣闊的電磁波波段具有前瞻的超薄光學元件應用，諸如透鏡、波片、角動量感應器、全像片等。然而目前的超穎介面調控方式由結構的尺寸、大小所決定，元件製作後性質即已固定，無法調控。具有動態調控式的超穎介面則為實現動態可重組的超平面光學元件的重要挑戰。本文主要設計與研究全彩超穎全像片與電調控式超穎介面。全彩超穎全像片由二維排列的鋁奈米棒/二氧化矽/鋁鏡組成的像素所構成，在可見光波段具有偏振選擇性、波長選擇性影像。藉由適當的窄頻設計，波長多工、色彩三原色的影像即可組合全彩影像。各種長度的鋁奈米棒陣列的反射光譜與設計吻合，具有多種顏色並可應用於奈米全彩調色。電調控式超穎介面則以透明導電氧化物材料(氧化銦錫) 的動態電場侷域性為基礎，設計與研究電調控式超穎介面。我們以閘極調控氧化銦錫的介電係數原理，電調控超穎介面的相位與振幅，並更進一步設計電調控式超穎介面元件。我們藉由結合半導體物理與電磁波的物理模型來設計與分析電調控式超穎介面。藉由不同的外加偏壓，我們研究電調控式超穎介面組成的動態相位陣列所形成的動態繞射條紋。此研究提出了以閘極電調控場效式超穎介面的設計原理，實現主動式超穎介面元件。

關鍵字

超穎材料；超穎介面；電漿子學；超穎全像片；全像術；奈米天線；透明導電氧化物；電調控；場效調控

並列摘要

Nowadays, vision technologies in various color applications are primarily targeting the three primary colors and their mixing in conjunction with control of light polarization. The scalar diffractive pattern of liquid crystal displays (LCD) or digital micro-mirror devices (DMD) employed in hologram renders polarization unswitchable. The metamaterials or metasurfaces employed surface electromagnetic wave are capable of shaping both amplitude phase and polarization of light over subwavelength length scales. They have been previously applied to broadband and broad-angle phase hologram with polarization-dependent images but failed to yield color multiplexing in the visible spectrum. In contrast, light information can be manipulated either in amplitude, phase, polarization, or frequency, and combination thereof. Chip based hybrid-plasmonic modulators made of incorporating nanoscale plasmonics and classic photonic elements has the fasted modulation speed and lowest energy-per-signal are proposed to overcome a limited propagation length and higher loss of a surface plasmon-polariton (SPP) mode. Metasurfaces composed of sub-wavelength artificial structures show promise for extraordinary light-manipulation and development of ultrathin optical components over a broad range of the electromagnetic spectrum. However structures developed to date do not allow for post-fabrication control of antenna properties. Metasurfaces incorporating dynamically tunable methods offer the unprecedented opportunities in reconfigurable flat optical devices. In this dissertation, a phase modulated multi-color meta-hologram (MCMH) and an electrically gate-tunable metasurface were design and investigated. The MCMH made of sandwich structure of Al-nanorod/SiO2/Al-mirror arranged in a two-dimensional array of pixels is polarization-dependent and capable of producing images in three primary colors. With proper design of the structure, we obtain resonances of narrow bandwidths to allow for implementation of the multi-color scheme. Experimental reflected spectrum for each kind of nanorods array are investigated, which is in agreement with the simulation results and certainly lead to full color applications using color mixing. We have investigated the integration of the transparent conductor indium tin oxide (ITO) active elements to realize gate-tunable phased arrays of subwavelength antenna in a reflectarray metasurface configuration to enable gate-tunable permittivity. The magnetic dipole resonance of each antenna interacts with the carrier density-dependent permittivity resonance of the ITO to enable phase and amplitude tunability. A multiphysics method incorporated semiconductor physics and electromagnetic waves are considered in the design and resonance analysis. A simple 2-level dynamic phase grating is investigated using the gate-tunable metasurface. With different applied biases, the controllable diffraction patterns have been investigated by dynamic phase grating system. This work provides a general design principle applicable to dynamic metasurface devices based on gate-tunable field effect.

並列關鍵字

Metamaterials ； metasurfaces ； plasmonics ； meta-hologram ； holography ； nanoantennas ； transparent conducting oxide ； electrically tunable ； field-effect modulation

參考文獻

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電漿子超穎介面於全彩全像片與電調控光學元件之應用

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