一維光子晶體奈米樑共振腔之研究

Abstract

相較於二維光子晶體共振腔，一維光子晶體奈米樑共振腔不僅在元件有效面積上大幅的縮小了一個維度，更具有能與二維共振腔系統相匹的高品質因子(Q)及極小模態體積(V)等優越的模態特性，所以非常適合於在未來高密度積體光路中做為光源、感測器或特定功能元件的應用。 利用多重異質結構的模隙侷限效應，我們提出了兩種一維光子晶體奈米樑奈米共振腔結構設計(空氣孔洞中心及介電材料中心)，以有限元素法快速地找出對應的模態分布和頻率，再從有限差分時域模擬方法去優化其Q值及V值。藉由半導體奈米製程，我們成功製作具有極小元件尺寸面積的奈米雷射。透過共焦顯微螢光光譜系統，我們成功地取得並驗證具有極低雷射閥值的單模雷射操作。此外，較小的元件尺寸面積亦造就較佳的力學結構特性，使其非常適合應用於流體環境中的折射率感測器。透過一維光子晶體奈米樑耦合共振腔設計，利用其偶耦合模態集中於耦合結構間隙 (環境介質)的場形分布，以偵測不同濃度的糖水溶液，來實現了其折射率光學感測之功能

One-dimensional (1D) photonic crystal (PhC) nanobeam (NB) cavity not only has the ultra-small device footprint but also has the comparable high quality (Q) factor and small mode volume (V) with two-dimensional (2D) PhC cavity. Therefore, 1D PhC NB cavity is very promising in realizing the application of active nanolasers, optical sensors, and other functional devices in the condensed photonic integrate circuits. In this thesis, we propose two 1D PhC nanocavity designs on suspended NB, the air-centered and dielectric-centered nanocavities. The optical confinement of nanocavity along the NB is provided by multi-hetero-interface with mode-gap effect. From the numerical simulation, finite element method is used for rapidly investigating mode profile and frequency and finite-difference time-domain is used for the Q and V optimization and. These two nanocavity designs are realized via nano-fabrication processes. By the near-infrared confocal micro-photoluminescence system, single mode lasing actions with low thresholds are achieved and addressed. Moreover, the good mechanical stability due to small device size makes this kind of device suitable for optical sensing. Thus, we propose the 1D PhC coupled-NB nanocavity for optical sensing via utilizing the unique mode distribution of the even mode. Optical sensing function is demonstrated via sensing water glucose water solution with different concentrations.