兩種改良型鋸齒狀長週期光纖光柵元件

Abstract

此論文結合壓印微影製程與濕蝕刻技術的新方法，可以比過去方法還更容易製作出鋸齒狀長週期光纖光柵(C-LPFGs)。此方法主用是利用壓壓印微影製程技術將聚碳酸酯(PC)製作成光纖的濕蝕刻擋罩。不僅如此，在鋸齒狀長週期光纖光柵被重新壓入另一個聚碳酸酯中後，聚碳酸酯還可以當作鋸齒狀長週期光纖光柵的包覆材料。因為此種方式可以讓聚碳酸酯提供給鋸齒狀長週期光纖光柵一些內部的應力，使光纖內部的折射率產生變化而製造出埋入式鋸齒狀長週期光纖光柵(EC-LPFGs)，此種埋入式鋸齒狀長週期光纖光柵不像鋸齒狀長週期光纖光柵，它不需要預先給予拉力即可作為拉伸應變、彎曲與溫度的感測器。 除此之外，我們利用蝕刻鋸齒狀長週期光纖光柵至直徑約數十微米可以成功製作出鋸齒狀長週期微光纖光柵(C-LPMFGs)。此種光纖光柵主要是因為鋸齒狀的結構造成有效折射率週期的變化，而且也不需要像鋸齒狀長週期光纖光柵要預先給予一拉伸應力。在蝕刻鋸齒狀長週期微光纖光柵時，共振波長在即時監控下被觀察到會隨著蝕刻進行迅速地飄移。此鋸齒狀長週期微光纖光柵作為溫度感測器時有每攝氏上升一度飄移負一百四十六皮米的靈敏度(-146 pm/°C)，且其對折射率的靈敏度也成功提升至約周遭折射率每上升一單位時飄移兩千一百奈米(2100 nm/RIU)。

We demonstrate a new method that could make possible the mass production of corrugated long period fiber gratings (C-LPFGs) more easily than previous works by utilizing imprint lithography on polycarbonate (PC) and wet etching techniques. Besides, PC is used not only as a mask of wet etching but also as an embedding material of C-LPFGs. After re-imprinting the C-LPFG into another PC to make embedded corrugated long period fiber gratings (EC-LPFGs), a built-in compressive stress can change the refractive indices of fibers based on the induced photo-elastic effect, and it can serve as strain, bending and temperature sensors without applying a pre-tensile strain. In addition, a corrugated long period microfiber grating (C-LPMFG) is fabricated by etching a C-LPFG down to tens of micrometers in diameter. It can be a grating because of the periodic effective index difference caused by the corrugated structures, which also has no need of applied pre-tensile strain. During the etching of C-LPMFGs, the result of in-situ monitoring of resonant wavelength shows that the wavelength shift varies rapidly. The C-LPMFG is shown as a temperature sensor with sensitivity of -146 pm/°C, and the SRI sensitivity is successfully enhanced to about 2100 nm/RIU.