Design and Fabrication of Ridge-type Directional Coupler on Gamma-ray Irradiated Lithium Niobate Substrate
Date Issued
2011
Date
2011
Author(s)
Huang, Hsin-Shun
Abstract
In this thesis, ridge waveguides are fabricated by using proton exchange and wet etching in gamma-ray irradiated lithium niobate(LiNbO3). Experimental results show the depths and aspect ratios of ridge structures are all improved, which gives rise to optical fields of higher aspect ratios and electro-optic modulators with better characteristics.
The ridge structures are obtained by proton exchange for 8 hr with various acid sources and etched for 8 hr with a mixture of hydrofluoric acid and nitric acid. The deepest depth and the aspect ratio of ridge structure are 4.472μm and 1.3 when the dosage of gamma-ray irradiation is 162.5krad.
Moreover, the coupling length is shortened by 8.2% when a ridge-type directional coupler is fabricated with gamma-ray irradiated lithium niobate, which indicates that coupling effect is enhanced due to gamma-ray irradiation. And the half-wave voltage is decreased by 37.94%, and the extinction ratio is increased by 46.54%. Thus, it shows that gamma-ray irradiation is advantageous for the improvement of lithium niobate integrated optical waveguides.
Subjects
absorbed dose
aspect ratio
benzoic acid
biaxial crystal
coupler
coupling effect
coupling length
directional coupler
electro-optical coefficient
electro-optic effect
electro-optical modulator
extinction ratio
gamma ray
half-wave voltage
lithium benzoate
optical field
optical ridge waveguide
overlap integral
proton exchange
PE
radioactivity
ridge depth
ridge sidewall
ridge structure
titanium
tantalum
Ti-indiffused optical waveguide
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-100-R98941015-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):93c30a0f2e311013086f7ab924a2ee87