以光柵反射器設計中空介質共振器與波導

Abstract

本論文將以光柵反射器的高反射器特性，將週期性的光柵圍成環狀光柵反射器作為cladding，將其視為一反射面使得電磁波能夠被侷限於由低折射率的空氣所組成的core內，藉由光柵反射器的高反射特性來設計中空介質共振器與中空介質波導。不同於傳統的光纖波導利用全內反射的機制，使得電磁波必須侷限於由高折射率介質所組成的core內，而利用光柵反射器做為cladding能使電磁波侷限在由空氣組成的core中，因此可運用於高功率的傳輸上。在中空共振器的設計上，若把光柵反射器當作一反射面使能量侷限於截面積方向形成共振，因此可視為一正向入射的光柵反射器，並透過調變介質的折射率對比與共振器的半徑大小比較對品質因子的改變。中空介質波導，則可視為一個平行溝槽方向入射的光柵反射器，將提供一個往z方向傳波的波向量，使得能量能侷限於空氣組成的core內，並往z方向上傳播，也將調變介質的折射率對比與波導管的半徑大小比較對衰減係數的改變。

In this studies, we show that the new type of hollow core dielectric cavities and waveguides. The structures consist of a circular grating reflector of high index material and low index air-core. Light is confined and guided inside the air-core by the high reflectance of circular grating reflectors that is differences in the traditional optical fiber. We hope to find the possibility to guide wave in low absorption loss medium by properly designing this kind of cavities and waveguides and be applied to high power transmission. We will first try to design he hollow core cavities that can be considered the grating reflectors under normal incidence. Light is reflected and confined at transverse direction by the high index grating reflector. In our simulation, we will change the index contrast of grating reflectors and the radius of air-core to compare the influence of Q factors. In addition to the case of hollow core cavities, we also try to study the waveguides which can be considered the incident waves has an angle between the circular grating reflectors wall. We will also change the index contrast of grating reflectors and the radius of air-core to compare the influence of attenuation constants