Sapphire based UV micro-optics elements fabricated by femtosecond laser direct writing and wet etching

Countdown
0 days

Template for Manuscripts

Important Dates

Conference:

Aug. 18-20, 2018

Full Paper Due: Jul. 20, 2018

Abstract Due: Jul. 20, 2018

Audience Registration Due:
Aug. 18, 2018

Presentations of The Int'l Symposium on Photonics and Optoelectronics (SOPO 2016)

● Sapphire based UV micro-optics elements fabricated by femtosecond laser direct writing and wet etching
Author(s)
Qiankun Li
Affiliation(s)
Jilin University
KEYWORDS
Sapphire based UV micro-optics elements, femtosecond laser
ABSTRACT
Sapphire is one of the most widely used optical materials for its excellent optical transparency from Mid-IR to UV and high hardness, thermal and chemical stabilities. For example, it can be used for never-worn optical window of cameras and watches, and especially harsh-condition-applicable windows of military infrared devices and space optics. However, some advantages and features of sapphire, such as chemical inertness and the largest hardness among oxide, make it difficult to process mechanically or chemically on the other hand. Traditional mechanical polishing process has limitations of high side damage, frequent rupture and tool wearing. As for chemical etching, etching speed is usually slow and changes with crystal lattice orientation, resulting in problems of processing efficiency and controllability. Lithography and nano-imprint could fabricate antireflec-tive sub-wavelength gratings on sapphire for light extraction efficiency enhancement, compared with direct laser writing, they have many drawbacks such as high costs, mask depended and com-plicated process. Here, we report sapphire-based Fresnel zone plate (FZP) and Dammann gratings (DGs), which is fabricated by femtosecond laser direct writing (FsLDW) assisted with subsequent wet etching. With this method, we solved the problem of high surface roughness caused by ultrafast femtosecond laser processing. Ultraviolet light focusing and imaging can be easily achieved by fabricated Fresnel zone plate. DGs that generated 2 × 2, 3 × 3, 4 × 4, and 5 × 5 spot sources in the fan-out as designed, and exhibited diffraction efficiency of 52%, 40%, 29%, and 53%, respectively, comparable with theoretical values. Due to the high material hardness, thermal and chemical sta-bilities of sapphire, such sapphire FZP may have great potential in UV imaging under some harsh environments. And sapphire-based DGs show great potential in UV beam shaping, UV beam splitting and laser parallel micro-processing.