全光纖式微震動感測器於水底聲波應用之研究

The study of all optic fiber micro-bibration sensors for Hydrophone applications.

莊曜謙(Yao-Chieng Chung)

指導教授 ： 蔡五湖

大同大學/電機資訊學院/光電工程研究所/碩士(2004年)

摘要

摘 要
在本篇論文裡，詳細探討了單模光纖的漸逝場特性、理論與側模光纖的相關應用，而側模光纖的各種不同製程亦被詳細的探討。論文裡並提出了兩種長週期光纖光柵微震盪感測器的架構。為了增加光纖感測器的靈敏度，我們先將光纖側磨至光纖孔徑的表面附近，然後使用感應偶合電漿乾蝕刻的方法，於光纖的側抛平面上蝕刻出一長週期的光纖光柵結構。此邊緣垂直的光柵結構不但提升了光纖光柵的靈敏度，並使感測器的感側頻率提升至百萬赫茲等級。而為了簡化光纖光柵的製作方法，我們使用了黃光微影技術與熱蒸鍍的方法於側磨光纖的表面上製成一長週期的薄膜光柵，不同的方法在本論文中被測試、評估，並探討其穩定性與靈敏度。接著以520赫茲的聲波頻率與42K赫茲的超音波頻率量測此光纖光柵感測器。此些由本實驗室提出之光纖光柵感測器具有各種優點，諸如小體積、製備容易與低花費。而在水底聲波之應用亦被證實有良好的表現。數種量測亦被提出且實驗證明其由低頻至高頻均有良好的響應。

關鍵字

光纖感測器；水聽器；微震盪；漸逝場；側磨；；

並列摘要

ABSTRACT
The characteristics and principles of the evanescent field for the side-polished single mode fiber are discussed, and the details of the various processes of fabricating the side-polished fibers are also described in this thesis. Furthermore, two kinds of the long period fiber grating (LPFG) micro-vibration sensors are presented. For increasing the sensitivity of the sensor, we polish the fiber into the evanescent region, and then fabricating a long period grating with rectangular groove structure on the side-polished surface by virtue of the ICP-RIE dry etching technique. This steep grating structure not only increases the sensitivity of the sensor, but also makes the sensing frequency up to the degree of MHz. In order to simplify the processes of the fabrication, we use the techniques of photolithography and thermal vaporization for the side-polished fiber to make up the thin film LPFG structure on the polished surface for acoustic wave sensing in the water. Several fabrication methods have been tested for the assessment of the sensitivity and stability analysis; two frequencies of the acoustic wave (520 Hz acoustic wave and 42K Hz ultrasonic wave) have been used in the experiment. The fiber grating sensors we proposed in this thesis posses several advantages, such as small size, easy fabrication, and low cost, as well as very good performances have been demonstrated and discussed for the hydrophone applications in the water. Several measurements are carried out, and the experimental results have very good frequency response from low to high frequency region.

並列關鍵字

fiber sensor ； hydrophone ； micro-vibration ； evanesce

參考文獻

[1] E. Udd, “Fiber Optic Smart Structures”, IEEE Proceedings. Vol. 84, pp. 60–67, 1996.

[2] G. G. Smith and E. W. Jr, Vitello, “Accelerated measurement of low BERs in fiber optic communication systems”, Optical Fiber Communication Conference, Vol. 2, pp. 334, 1999.

[3] J. M L. Higuera, A. Cobo, J. Echevarria, F. J. Madruga, and J. L. Arce, “Simultaneous temperature and acceleration optical fiber sensor system for large structures monitoring”, IEEE Lasers and Electro-Optics Society, Vol. 2, pp. 462–463, 2000.

[4] B. Guldimann, P. A. Clerc, and N. F. D. Rooij, “Fiber-optic accelerometer with micro-optical shutter modulation and integrated damping”, IEEE Optical MEMS, pp. 141–142, 2000.

[5] J. E. Webb, “Accelerated testing of liquid crystal components for use in optical networking devices”, Optical Fiber Communication Conference, Vol. 4, pp. ThB1-1–ThB1-3, 2001.