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

近來，在光纖端面製作微奈米結構十分受矚目，因為光纖細小，成本低及易於量產的特性，適合應用在感測器、通訊和導光方面。除了文獻中已有的應用報導外，我們提出在光纖端面製作相位光柵，並使用此種端面具有相位光柵的光纖，可輕易地將雷射光導至任意形狀的試片上面，直寫干涉條紋。 在此論文中，我們將會利用商用軟體R-soft來模擬不同結構形狀的相位光柵的繞射效率，以及利用雙光干涉微影術來製作相位光柵。並且利用在離子蝕刻機(RIE)中蝕刻擋罩縮小的機制，簡單地將梯形相位光柵製作在玻璃基板及光纖端面上。而後，我們會針對這些不同高度及填滿率(duty cycle)的結構，對壓抑0階繞射光的影響進行量測以及討論。 在製作梯形相位光柵在光纖束(fiber bundle)的端面方面，我們設計並製作了光纖束。製作光纖束的過程中，較大的石英柱半徑可在旋轉塗佈阻劑時，擁有較均勻的膜厚。而我們設計製作光纖束的直徑為15公厘，可以提供足夠大的面積做旋轉塗佈阻劑，並有效降低邊緣不均勻的現象。在經過干涉微影及半導體製程後，完整無破損的相位光柵可製作在光纖束的端面上。再使用端面具有相位光柵的光纖，將一維光柵製作在一微米尺寸的區域。除此之外，在曲面上直寫週期性結構預期也是可行的。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