在二氧化矽基板上具有小圖型尺寸的光子晶體奈米結構雷射特性

Abstract

在二氧化矽基板上具有小圖形尺寸的光子晶體雷射不僅具有結構穩定的特性，更適合整合於積體光路中做為光源元件。而透過三五族材料整合於矽基材料上的奈米結構，更被視為矽奈米光學中有效發光元件的解決方案之一。 在本論文中，透過兩種光子晶體加強光－物質交互作用的機制，輔以 DVS-bis-Benzocyclobutene黏著接合技術，我們在二氧化矽基板上實現具有小圖形尺寸的光子晶體雷射元件。第一種方式是利用晶格對稱點附近具有極小群速度的光子平帶。基於此機制，我們透過二維正方晶格光子晶體中M對稱點的平帶來實現在二氧化矽基板上的帶緣雷射，並做為後續的對照組。接著，藉由消除一個方向的光子晶體，我們在二氧化矽基板上進一步地實現一維光子晶體奈米樑帶緣雷射，其展現出來的元件尺寸以及雷射閥值皆比二維正方晶格光子晶體帶緣雷射來的小。第二種方式則是以形成共振腔來加強光－物質交互作用。基於此機制，我們利用封閉一維光子晶體奈米樑的概念來形成一種新穎的一維光子晶體環形共振腔，在實驗上所展現出來的元件圖形尺寸只有30 μm2，且其環形直徑僅有3.56 μm。而在實驗上最小能夠觀察到雷射行為的環形直徑僅3 μm。此外，我們進一步地在一維光子晶體環形結構中設計具有模隙侷限效應的奈米共振腔。相較於一維光子晶體環形共振腔，我們從此種雷射元件可取得較小的模態體積以及較低的雷射閥值。除了極小的元件圖形尺寸外，此類環形光子晶體共振腔可透過側向光波導耦合的方式，在整合於積體光路時，在耦合機制上展現絕佳的可變化性。

Photonic crystal (PhC) lasers with small device footprint on silicon-dioxide (SiO2) substrate not only has mechanically stable property but also is a good candidate for light sources in condensed photonic integrated circuits (PICs). Moreover, III-V active materials on silicon-based substrate are regard as a feasible solution of efficient light sources in silicon photonics. In this thesis, based on two different mechanisms for enhancing light-matter interactions, DVS-bis-Benzocyclobutene adhesive bonding is utilized to realize ultra-compact PhC lasers on SiO2. The first method is using the flat photonic bands with very low group velocities near the highly symmetric points of PhCs. Via this mechanism, two dimensional (2D) square-PhC band-edge (BE) lasers at M symmetric point are demonstrated for reference. Via eliminating the PhCs in one dimension, we further demonstrate one-dimensional (1D) PhC nanobeam (NB) BE lasers on SiO2 substrate. Such devices not only have smaller device footprints but also lower threshold value than those of 2D-square PhC BE lasers. The second method is forming resonators to enhance light-matter interactions. Via this mechanism, we propose and realize a novel 1D PhC ring resonator (PhCRR) on SiO2, a design formed by encircling 1D PhC NB. This kind of device also shows small device footprint of 30 μm2. The minimum ring diameter for lasing in experiments is 3 μm. Furthermore, we also design a mode-gap confined nanocavity on 1D PhCR. Smaller mode volume and lower lasing threshold than those of 1D PhCRRs are obtained. In addition to small device footprints, lasers based on PhCRs also show good flexibility for integrating in PICs via side-coupled ridge waveguides.