Fabrication and Application of Binary Phase Grating on a Fiber End by Utilizing Interference Lithography

Recently the fabrication of micro and nano structures on optical fiber ends has attracted attention. Because of low cost, mass production, and small size, optical fibers are appropriate medium for sensing, communication, and light guiding applications. Besides the reported applications, we also proposed an idea that fabrication of a binary phase grating (BPG) on the facet of an optical fiber. By using such a BPG-equipped fiber, a laser beam could be guided to any exposure plane to directly write interference fringes on a substrate of any shape.
In this thesis, we will simulate the diffraction efficiencies of BPGs with various shapes by using the commercial software, R-soft, and fabricate BPGs on quartz substrates and fiber bundle by utilizing two-beam interference lithography and semiconductor processing. Moreover, by using the ARC layer as the etching mask, the trapezoid-shape of gratings would be fabricated naturally. Subsequently, the suppression of 0th order beam diffraction efficiency of different samples influenced by the height and duty cycle is studied.
For fabricating trapezoid BPG on the end of fiber bundle, the fiber bundle was designed and fabricated by ourselves. The radius of fiber bundle cylinder needed to be large enough to have good uniformity for spin coating. Ours was 15 mm, and it could provide enough large area for spin coating, the effect of edge bead could be reduced. After semiconductor processing, the non-fragmented BPG on the top of fiber bundle would be obtained. By utilizing the fiber equipped BPG, we could fabricate one dimension grating with micro-scale area. Furthermore, to directly write periodic structures on a curved surface would be possible.