具有新穎奈米鉗結構之可調一維光子晶體奈米共振腔雷射

1D Photonic Crystal Tunable Nanocavity Lasers with Novel Nanoclamp Structure

王良誌(Liang-Jhih Wang)

指導教授 ： 李柏璁

國立交通大學/電機學院/光電工程系所/碩士(2018年)

摘要

在此篇論文中，承繼既有埋於可形變材料中的一維光子晶體可調奈米共振腔雷射結構，並基於其在每單位百分比應變的大波長響應率（7.8 nm）基礎下，我們進一步提出一種新穎的奈米鉗結構鑲嵌於一維光子晶體的兩側，此一奈米鉗結構可局部於元件周遭創造出一非理想彈性區域，使得元件在線性受力下於箝制區與非箝制區產生非均勻之應變，從而實現波長響應率大幅提升之目的。
本研究首先透過力學上的數值模擬來驗證此一奈米鉗確實可於外力施加下，對一維光子晶體結構造成不均勻形變之效果，輔以光學數值計算確認相對應的可調光學特性改變；我們更進一步地透過奈米鉗各個結構參數對可調光學特性影響的探討，瞭解其機制並建立簡單的設計原則。
而基於既有的半導體奈米製程技術，我們針對奈米鉗結構需求優化其製程步驟，以改善之良率實現該元件設計；除了在量測上確認其低雷射閾值之單模雷射操作外，我們更逐一以實驗驗證在數值模擬上對元件的種種預測，最終該些元件在各參數下之波長響應率可普遍明顯提升至10 ~ 12 nm的範圍；而透過前述理論與實驗所建立的設計原則，我們也在理論上提出具有將波長響應率進一步大幅提升至15.9 nm之設計。
而本研究同時在理論與實驗上研究將此一奈米鉗結構應用在一維光子晶體波導的特性，利用前述奈米鉗造成不均勻形變的機制，可以直接以力學的方式在均勻的光子晶體晶格上創造出具有高品質因子之奈米共振腔，亦即透過波導－奈米共振腔的轉換，實現隨選（on-demanded）、可再現（reproducible）奈米共振腔雷射之可能。
我們相信本研究所提出結構力學與光學的新穎混合設計，在可撓式積體光路中作為奈米力學光感測器或雷射元件上，是相當有趣且提供了另一種極具潛力的可能性。

關鍵字

光子晶體 ； 可調奈米雷射 ； 應力增強

並列摘要

In this thesis, based on the large wavelength response per percentage strain (7.8 nm) of 1D photonic crystal (PhC) tunable nanocavity laser, we further propose and setup novel nanoclamps nearby both sides of 1D PhCs. It can create a non-ideal elastic region to produce non-uniform structural deformation distribution under an applied linear stress. Owing to the different deformation between the clamped and unclamped regions, the wavelength response of the device can be significantly enhanced.
At first, via the mechanical/optical numerical simulation based on finite-element method, we confirm the non-uniform deformation of 1D PhC nanocavity with nanoclamp under different strains, as well as the corresponding tunable properties of the resonance mode inside. By further discussing the optical properties of 1D PhC nanocavities with different nanoclamp parameters, the enhancing mechanism is initially clarified and used for establishing simple design rules.
Based on our previous nanofabrication techniques, we further optimize the process to meet the requirements of nanoclamp structure, which realizes this design and improves its yielding rate. The devices not only show single mode lasing operations with low lasing thresholds in measurements, but also show good matchings with the simulation results. The experimental wavelength responses can be enhanced to 10–12 nm under different nanoclamp parameters. In addition, we also theoretically propose an optimized design with wavelength response as large as 15.9 nm.
On the other hand, the nanoclamp is also applied on 1D PhC waveguide without defect design both in simulation and experiment. Via the non-uniform deformation caused by nanoclamp under stress, a nanocavity with high quality factor can be created. This implies that an on-demanded and reproducible nanocavity laser could be achieved by this strain-induced waveguide-nanocavity conversion.
We believe our proposed novel mechanical/optical hybrid design in this study would provide interesting and highly potential possibilities for optical strain sensors and nanolasers in flexible photonic integrated circuits.

並列關鍵字

Photonic Crystal ； Tunable Nanolasers ； Strain Engineering ； PDMS

參考文獻

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