可溶解、可印刷及可自修復隨機雷射光學元件

Abstract

雷射無疑是二十一世紀人類最重要的光源之一，此研究論文專注在設計、製造、演示軟性且耐用的新一代隨機雷射元件。有別於傳統雷射元件，隨機雷射具有許多先天優勢，例如可彎曲、低成本和設計簡單等性質。近十年來隨機雷射一直是雷射領域的研究熱點。我們相信這種無鏡面雷射系統將在後續的雷射光學技術發展中發揮決定性和不可替代的作用。 1. 可溶解回收隨機雷射元件 現今社會對醫療品質的重視及環保意識的抬頭催生了可溶解可回收光電元件的大量需求。無疑地，雷射在人類現今社會中扮演極為重要的角色。然而，想要讓傳統雷射元件系統實現瞬態特性卻非常具有挑戰性，由於傳統雷射元件需要製造精確的光學共振腔，而其組成元件的材料又有其高度的限制性及特殊性。相反地，基於無序介質中多重光子散射的隨機雷射是實現瞬態甚至可循環回收再利用的良好雷射系統。此研究我們成功設計並演示了一個基於綠色材料的可溶解回收集成隨機雷射元件。隨著在水中溶解的時間增加，隨機雷射強度會開始遞減而雷射元件的閾值會開始增加，完全溶解後，我們可經由簡易的製程方法回收材料，重新製作成全新的雷射元件。除此之外，製程環保也是我們著眼的重點項目，傳統的光電元件使用了使多有化學酸鹼蝕刻製程，常常伴隨重金屬廢物或者難以分解回收的材料，除了浪費有限的自然資源，也對生存環境造成難以回復的傷害。我們選擇的材料皆為無毒、環境可分解甚至是人體可吸收之材料，最小化產品對環境的影響，環保瞬態的概念將會是下一世代光電元件的重要參考指標。 2. 噴墨印刷隨機雷射元件 當今印刷技術的革新已經徹底扭轉人類對光電元件設計及製造的想像，特別是在可穿戴設備和一次性設備方面更可以看出端倪。近期印刷光電元件進展包括太陽能電池、電容器、傳感器、發光二極體、顯示器及智能標籤等。此研究展示的噴墨印刷隨機雷射元件及時填補了現今印刷光電元件所缺乏的雷射系統。我們成功使用一般商用噴墨印表機製造隨機雷射元件，自行研發製造的紅黃綠藍隨機雷射墨水的光譜範圍更涵蓋人類視覺75%的色域。一系列隨機雷射研究領域期待已久的概念驗證包括隨機雷射照明模組，隨機雷射顯示面板原型及隨機雷射墨水加密印刷技術都於此研究計畫中成功演示。 3. 自修復隨機雷射元件 近年來穿戴式光電元件、軟性光電元件在各領域的快速發展，有別於傳統光電元件，其特色在於彈性、延展性、超薄結構、輕量化、攜帶性，整合多功能的光電元件更有利廣泛領域之應用。然而，這類新形態軟性光電元件耐用度備受質疑。為了解決此項工程挑戰，科學家開始投入開發不僅可撓、可拉伸且可自修復的元件。目前，有部分自修復的元件已經成功實現，包括感測元件、生物感測器、記憶體、電晶體、能源元件、電子皮膚。雷射無疑是二十一世紀人類最重要的光源之一，此研究計畫將專注在設計、製造、演示軟性且耐用的自修復雷射元件。此自修復隨機雷射元件可以承受日常重複的應力應變，面臨突如其來重大的破壞也可以在幾秒鐘內後恢復雷射系統運作。自修復的機制不需要外加的能量及化學的黏著劑，在常溫常壓的環境下即可完成。

Random lasers hold abundant inherent advantages compared to conventional lasers, such as soft, cost-effective, and simple design. It has been a hot research topic in recent decades. We believe and foresee that such mirror-free laser system can and will play a decisive and irreplaceable role in the follow-on laser technology advancements. In this thesis, for the first time, we have successfully developed three different kinds of random lasers with new functionalities, which are very useful for broadening of random lasers for practical applications in a wide range area. 1. Dissolvable and Recyclable Random Lasers Optoelectronics with transient and recyclable properties represent an emerging technology in the modern world for the growing requirements of healthcare quality and the rising awareness of environmental protection. As is well known, lasers play a very important role in human society. However, achieving transient characteristic by traditional lasers can be very challenging, due to the precise optical resonator cavities with meticulous fabrications and special components. On the contrary, random lasers, based on the multiple light scattering in a disorder medium, are of good candidates for achieving transient and even recyclable function. An integrated random laser based on green materials with dissolubility and recyclability is created and demonstrated. The dissolvable and recyclable random laser (DRRL) can be dissolved in water accompanying with the decay of emission intensity and the increment in lasing threshold. Furthermore, the DRRL can be reused after the process of de-ionized treatment, exhibiting excellent reproducibility with several recycling processes. 2. Inkjet Printed Random Lasers Printing technology nowadays has led to a multitude of revolutions in design, conception, fabrication, and application of optoelectronics especially for the wearables and one-off devices. Recent advances range from solar cells, batteries, sensors, LEDs, displays, biomedical widgets, to smart tags. Inkjet printed random lasers (IPRLs) demonstrated here timely fills up the crucial but missing piece of puzzle in the printed optoelectronics as well as the laser research progress. A broad emission spectrum of IPRL inks covering more than 75% gamut of CIE color space has been successfully exploited and well adopted by the commercial desktop inkjet printers. Furthermore, based on this digital, ink-efficient, mask-free patterning, and drop-on-demand printing technique, a series of long-anticipated proofs-of-concept including on-chip laser lighting modules, RYGB pixel-based laser displays, and ink-crypto/laser-coded security printing technique have also been demonstrated. 3. Self-healing Nanophotonics: Robust and Soft Random Lasers Self-healing technology promises a generation of innovation in cross-cutting subjects ranging from electronic skins, wearable electronics to point-of-care biomedical sensing modules. Of late, scientists have successfully pulled off significant advances in self-healing components including sensors, energy devices, transistors, and even integrated circuits. Laser, one of the most important light sources, integrated with autonomous self-healability should be endowed with more functionalities and opportunities, however, the study of self-healing laser is absent in all published reports. Here, the first soft and self-healable random laser (SSRL) is presented. The SSRL can not only endure extreme external strain but also withstand several cutting/healing test cycles. Particularly, the damaged SSRL enables to restore its functionality within just few minutes without the need of additional energy, chemical/electrical agents, or other healing stimuli, truly exhibiting a supple yet robust laser prototype. It is believed that SSRL can serve as a vital building block for the next-generation laser technology as well as the follow-on self-healing optoelectronics.